A method for fast calculation of sound field induced by internal wave excited by a source of flow-acoustic coupling

Abstract

The application relates to the technical field of underwater acoustic detection, in particular to a source-induced internal wave induced sound field fast calculation method based on flow sound coupling, which comprises the following steps: establishing a layered ocean environment, a required coordinate system and a target motion model for an underwater moving target, and calculating a source-induced internal wave three-dimensional flow field analytical solution; based on the source-induced internal wave three-dimensional flow field analytical solution and background sound velocity, calculating a disturbance sound velocity profile at each moment, and then adding the disturbance sound velocity profile to the background sound velocity to obtain a total sound velocity profile at each moment; based on the background sound velocity, determining a channel condition under the action of the source-induced internal wave, and then based on the total sound velocity profile, determining a channel condition under the action of the source-induced internal wave; calculating a disturbance Green function, combining a sound source spectrum, and calculating a source-induced internal wave induced sound field; and finally, based on the calculated source-induced internal wave induced sound field, performing source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis and parameter optimization. The method significantly reduces the calculation resource consumption of the source-induced internal wave induced sound field and improves the calculation efficiency.

Description

Technical Field

[0001] The embodiments of this application relate to the field of underwater acoustic detection technology, and in particular to a method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling. Background Technology

[0002] In the marine environment, seawater forms a stable stratified structure due to density stratification caused by changes in temperature and salinity with depth. In such density-stratified media, when subjected to external disturbances, a wave phenomenon propagating within the seawater can be excited at the internal density stratification interfaces; this phenomenon is called internal ocean waves. Internal ocean waves are an important component of ocean dynamic processes, with wavelengths ranging from hundreds to thousands of meters and amplitudes exceeding several meters. They are characterized by concentrated energy, long propagation distances, and significant impacts on the underwater acoustic environment.

[0003] The generation mechanisms of ocean internal waves mainly include natural factors such as tidal topographic interaction, wind stress forcing, and ocean current shear instability. However, with the development of underwater vehicle technology, a special internal wave phenomenon directly excited by underwater moving bodies (underwater moving targets) has gradually attracted attention, namely, source-induced internal waves.

[0004] So-called origin-induced internal waves refer to the internal wave field generated and radiated behind an underwater moving target when navigating in a density-stratified ocean. This is caused by the volumetric displacement effect and hydrodynamic disturbance, which exert a continuous external force on the surrounding stratified flow field, resulting in fluctuations in local density and sound velocity distribution. This internal wave field propagates outwards along the target's trajectory in the form of a wake, forming an internal wave wake with specific spatial structure and temporal evolution characteristics. Because it originates from the target's own physical motion rather than radiated noise or electromagnetic signals, it possesses strong stability and is difficult to suppress, making it difficult to eliminate using traditional silencing, stealth, or electromagnetic shielding techniques.

[0005] To suppress the influence of induced internal waves, the first step is to analyze these waves. Traditional methods, under realistic, complex layering and geometric conditions, rely heavily on CFD (Computational Fluid Dynamics) and finite element methods. However, these methods suffer from high computational costs, sensitivity to assumptions, and convergence difficulties, making it challenging to support rapid calculations of induced sound fields and subsequent parameter sweeping and optimization studies. Furthermore, flow-acoustic coupling experimental data is scarce, and simultaneous observation of the flow and sound fields is difficult. Therefore, engineering applications require a rapid computational framework based on mature theories that can provide general laws governing induced sound fields. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of this application propose a rapid calculation method for source-induced internal wave-induced sound fields using flow-acoustic coupling. While ensuring the ability to characterize the general laws and typical features of source-induced internal wave acoustic effects, the calculation is transformed from high-cost numerical solutions of flow and sound fields into a combination of fluid analytical field generation, background propagation one-time solution, and time snapshot perturbation update. This allows for rapid calculation of the induced sound field, facilitating mechanism analysis, sensitivity analysis, and parameter optimization of source-induced internal wave acoustic effects.

[0007] To achieve the above objectives, embodiments of this application propose a rapid calculation method for source-induced internal wave-induced sound field in flow-acoustic coupling. The method includes: establishing a layered marine environment, a required coordinate system, and a target motion model sequentially for an underwater moving target, and calculating the analytical solution of the three-dimensional flow field of source-induced internal waves; calculating the disturbance sound velocity profile at each moment based on the analytical solution of the three-dimensional flow field of source-induced internal waves and the background sound velocity, and then adding it to the background sound velocity to obtain the total sound velocity profile at each moment; determining the channel conditions under passive internal wave action based on the background sound velocity, and then determining the channel conditions under active internal wave action based on the total sound velocity profile; calculating the disturbance Green's function based on the channel conditions under passive internal wave action and the channel conditions under active internal wave action, and calculating the source-induced internal wave-induced sound field based on the disturbance Green's function and the sound source spectrum; and performing source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis, and parameter optimization based on the calculated source-induced internal wave-induced sound field.

[0008] To achieve the above objectives, embodiments of this application also propose a rapid calculation system for source-induced internal wave-coupled acoustic fields. The system includes: a model building module, used to sequentially build a layered marine environment, the required coordinate system, and a target motion model for an underwater moving target, and calculate the analytical solution of the source-induced internal wave three-dimensional flow field; a sound velocity profile calculation module, used to calculate the disturbance sound velocity profile at each moment based on the analytical solution of the source-induced internal wave three-dimensional flow field and the background sound velocity, and then add it to the background sound velocity to obtain the total sound velocity profile at each moment; and a channel condition determination module. The system is designed to determine the channel conditions under passive internal wave action based on the background sound velocity, and then determine the channel conditions under active internal wave action based on the total sound velocity profile. The active internal wave induced sound field calculation module calculates the perturbation Green's function based on the channel conditions under both passive and active internal wave action, and calculates the active internal wave induced sound field based on the perturbation Green's function and the sound source spectrum. The application module performs acoustic effect mechanism analysis, sensitivity analysis, and parameter optimization based on the calculated active internal wave induced sound field.

[0009] To achieve the above objectives, embodiments of this application also propose an electronic device, including a processor and a memory, wherein the memory stores instructions executable by the processor, and the processor is configured to execute the instructions such that the electronic device can implement a method for rapid calculation of source-induced internal wave sound field by flow-sound coupling as described above.

[0010] To achieve the above objectives, embodiments of this application also propose a computer-readable storage medium storing a computer program that, when executed by a processor, enables a method for rapid calculation of source-induced internal wave sound field in flow-acoustic coupling as described above.

[0011] Optionally, the step of sequentially establishing a layered marine environment, the required coordinate system, and the target motion model for the underwater moving target includes:

[0012] Establish a Cartesian coordinate system in a flat seabed and a three-dimensional computational domain. ;in, , , These represent the x-coordinate, y-coordinate, and vertical coordinate of the Cartesian coordinate system, respectively.

[0013] With the underwater moving target as the origin, the negative direction of the underwater moving target's heading as the positive X-axis, and the sea surface direction as the positive Z-axis, a body coordinate system is established according to the right-hand rule. ;in, Represents the x-coordinate of the volume coordinate system. , For a constant speed of movement of an underwater target, For the motion time of the underwater moving target, the vertical coordinates of the body coordinate system are the same as those of the Cartesian coordinate system;

[0014] Establish a spherical coordinate system ;in, , , These represent the radial distance, pitch angle, and azimuth angle in spherical coordinates, respectively. , , ;

[0015] Given background density and background sound velocity profile ,based on and Calculate the buoyancy frequency of the water body ;

[0016] The underwater moving target is simplified to a radius of... An ideal sphere, with a center depth of . At the initial position Maintaining a constant speed According to the heading angle in the horizontal plane Linear motion, motion time is The target motion model of an underwater moving target can then be represented as:

[0017] ;

[0018] in, A target motion model representing an underwater moving target.

[0019] Optionally, the calculation of the analytical solution of the three-dimensional flow field of the source-induced internal wave includes:

[0020] The three-dimensional vertical amplitude of the source-induced internal wave field is calculated using the following formula, based on the analytical solution of the source-induced internal wave from a slowly moving spherical target:

[0021] ;

[0022] ;

[0023] ;

[0024] ;

[0025] in, For the Heaviside function, Indicates the observation point. That is, the observation point The three-dimensional vertical amplitude of the source-induced internal wave field at the location, For the amplitude term, It is a first-order spherical Bessel function. For phase terms, Let be the radius of the underwater moving target. The frequency of buoyancy in water. The constant speed for underwater moving targets.

[0026] Optionally, the step of calculating the disturbance sound velocity profile at each moment based on the analytical solution of the three-dimensional flow field of the source-induced internal wave and the background sound velocity, and then adding it to the background sound velocity to obtain the total sound velocity profile at each moment, includes:

[0027] Internal waves can disturb the local flow field, leading to fluctuations in fluid density and sound velocity, thus affecting the observation point. The speed of sound at a disturbance point is defined as This process occurs in the time domain. If the time interval is discretized, then the observation points The first The perturbation sound velocity profile at time t is expressed by the formula:

[0028] ;

[0029] in, Background sound velocity profile For marine environmental constants, The frequency of buoyancy in water. For observation point The first The three-dimensional vertical amplitude of the source internal wave field at time t. For observation point The first The velocity profile of the disturbance at any given moment;

[0030] If the total sound velocity profile under the influence of the source-induced internal wave is considered as the sum of the background sound velocity profile and the disturbance sound velocity profile, then the observation point... The first The total sound velocity profile at time t is expressed by the formula:

[0031] ;

[0032] in, For observation point The first The total sound velocity profile at any given time.

[0033] Optionally, determining the channel conditions under passive induced internal waves based on the background sound speed includes:

[0034] The channel condition under passive induced internal wave action is expressed by the Helmholtz-Kirchhoff equation as follows:

[0035] ;

[0036] in, yes The abbreviation for observation point Undisturbed background density at that location This indicates calculating the gradient. Indicates the location of the sound source. yes The abbreviation for Green's function indicates the background function. For the frequency of the sound source, Let be the impulse function of the sound source. Background sound velocity profile.

[0037] Optionally, determining the channel conditions under active internal wave action based on the total sound velocity profile includes:

[0038] Under the influence of source-induced internal waves, the medium density and sound velocity are considered as a superposition of background and local disturbances, resulting in anomalies in the corresponding channel acoustic transmission characteristics and the total Green's function. Decomposed into , yes abbreviation, yes The abbreviation for Green's function is used to represent the perturbation function.

[0039] The channel condition under active internal wave action is expressed as:

[0040] ;

[0041] in, yes The abbreviation for observation point The background density of the disturbance at that location That is, the observation point Total background density at the location, , yes The abbreviation for observation point The first The total sound velocity profile at any given moment. yes The abbreviation for observation point The first The perturbation speed profile at any given moment.

[0042] Optionally, the calculation of the perturbation Green's function based on the channel conditions under passive induced internal wave action and the channel conditions under active induced internal wave action includes:

[0043] The perturbation Green's function is calculated by subtracting the channel conditions under active internal wave action from those under passive internal wave action. , Represented as:

[0044] ;

[0045] ;

[0046] in, For the observation point, Indicates the location of the sound source. express and The position between, express and The space between As a sound pressure field sensitive core, for and The angle between them for and The angle between them for Background sound velocity profile at that location. for The velocity profile of the disturbance at that location. for Undisturbed background density at that location for The background density of the disturbance at that location;

[0047] The sound field induced by source-induced internal waves is calculated based on the perturbation Green's function and the sound source spectrum. This can be achieved through the following formula:

[0048] ;

[0049] in, The motion time of an underwater moving target. The sound source spectrum, It is the imaginary unit.

[0050] This application proposes a rapid calculation method for source-induced internal wave-induced sound field under typical shallow sea strata conditions. The underwater moving target is simplified to an ideal sphere, and a three-dimensional vertical displacement field is established using the analytical theory of source-induced internal waves. The density and sound velocity disturbances caused by internal waves are mapped to time-varying acoustic parameter disturbances. Under a first-order approximation, the acoustic wave equation is decomposed into background and anomaly terms, and a first-order perturbation update formula based on background sound rays (or modes) is constructed to achieve rapid updates of the channel Green's function and multipath delay / amplitude, ultimately obtaining the spatiotemporal distribution of the induced sound field. This method follows a unidirectional coupling framework of "target, flow field, and sound field," significantly reducing computational resource consumption and improving computational efficiency, thus facilitating the analysis of the acoustic effect mechanism, sensitivity analysis, and parameter optimization of source-induced internal waves. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies of this application will be briefly introduced below. Obviously, the following drawings are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings described herein are only used to explain this application and are not intended to limit this application.

[0052] Figure 1 This is a flowchart of a method for rapid calculation of source-induced internal wave sound field in a flow-sound coupling embodiment provided in this application;

[0053] Figure 2 This is a detailed schematic diagram of a method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling provided in one embodiment of this application;

[0054] Figure 3 This is a schematic diagram of the vertical distribution of seawater stratification provided in one embodiment of this application;

[0055] Figure 4 This is a schematic diagram of the distribution of the vertical displacement of the internal wave at different depths in a horizontal section provided in one embodiment of this application;

[0056] Figure 5 This is a schematic diagram of the vertical distribution of background sound velocity provided in one embodiment of this application;

[0057] Figure 6 This is a schematic diagram of the sound speed disturbance caused by the wave at different times provided in one embodiment of this application;

[0058] Figure 7 This is a schematic diagram of the sound field propagation loss before and after the influence of internal waves provided in one embodiment of this application;

[0059] Figure 8 This is a schematic diagram of the calculation results of the source-induced internal wave sound field provided in one embodiment of this application;

[0060] Figure 9 This is a schematic diagram of the structure of a fast calculation system for source-induced internal wave sound field of stream acoustic coupling provided in another embodiment of this application;

[0061] Figure 10 This is a schematic diagram of the structure of an electronic device provided in another embodiment of this application. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. Those skilled in the art will understand that many technical details have been presented in the embodiments of this application to facilitate better understanding. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this application. The following embodiments can be combined with and referenced by each other without contradiction.

[0063] To overcome the shortcomings of the prior art, one embodiment of this application proposes a fast calculation method for source-induced internal wave sound field of flow-sound coupling. The implementation details of the fast calculation method for source-induced internal wave sound field of flow-sound coupling proposed in this embodiment are described in detail below. The following implementation details are provided for ease of understanding only and are not necessary for implementing this solution.

[0064] This embodiment employs a fast calculation framework for induced sound fields using an "analytical internal wave field + first-order perturbation sound propagation coupling" approach. While ensuring the ability to characterize the "general laws and typical features" of source-induced internal wave acoustic effects, it transforms the calculation from high-cost flow / sound field numerical solutions into "fluid analytical field generation + background propagation one-time solution + time snapshot perturbation update", thereby rapidly calculating the source-induced internal wave induced sound field.

[0065] The specific process of the rapid calculation method for source-induced internal wave sound field of the flow-acoustic coupling proposed in this embodiment can be described as follows: Figure 1 As shown, its visual details are as follows Figure 2 As shown, the method includes:

[0066] Step 11: For underwater moving targets, establish the layered marine environment, the required coordinate system, and the target motion model in sequence, and calculate the analytical solution of the three-dimensional flow field of the source-induced internal wave.

[0067] In this specific implementation, this embodiment first establishes a layered marine environment, the required coordinate system, and the target motion model for the underwater moving target in sequence, and then calculates the analytical solution of the source-induced internal wave three-dimensional flow field based on these three elements.

[0068] In one example, the required coordinate systems include Cartesian coordinates, body coordinates, spherical coordinates, etc.

[0069] Regarding the Cartesian coordinate system, this embodiment establishes a Cartesian coordinate system in a flat seabed and a three-dimensional computational domain. ,in, , , These represent the x-coordinate, y-coordinate, and vertical coordinate of the Cartesian coordinate system, respectively.

[0070] Regarding the body coordinate system, this embodiment uses the underwater moving target as the origin, the negative direction of the underwater moving target's heading as the positive direction of the X-axis, and the sea surface direction as the positive direction of the Z-axis. The body coordinate system is established according to the right-hand rule. ,in, Represents the x-coordinate of the volume coordinate system. , For a constant speed of movement of an underwater target, For the motion time of the underwater moving target, the vertical coordinates of the body coordinate system are the same as those of the Cartesian coordinate system.

[0071] Regarding the spherical coordinate system, this embodiment establishes a spherical coordinate system. ;in, , , These represent the radial distance, pitch angle, and azimuth angle in the spherical coordinate system, respectively. Transformation between spherical and body coordinate systems... , , .

[0072] In one example, given background density (Total background density) and background sound velocity profile This embodiment is based on and It can calculate the buoyancy frequency of water. , , It is the acceleration due to gravity. The density at the center of the seawater stratum (undisturbed background density).

[0073] Next, a target motion model for the underwater moving target will be established, simplifying the underwater moving target to a radius of... An ideal sphere, with a center depth of . At the initial position Maintaining a constant speed According to the heading angle in the horizontal plane Linear motion, motion time is .

[0074] The target motion model of an underwater moving target can then be represented as:

[0075] ;

[0076] in, A target motion model representing an underwater moving target.

[0077] Based on the target motion model, the three-dimensional vertical amplitude of the source-induced internal wave field is calculated using the following formula, based on the analytical solution of the source-induced internal wave of the slow-moving spherical target:

[0078] ;

[0079] ;

[0080] ;

[0081] ;

[0082] in, For the Heaviside function, Indicates the observation point. That is, the observation point The three-dimensional vertical amplitude of the source-induced internal wave field at the location, For the amplitude term, It is a first-order spherical Bessel function. For phase terms, Let be the radius of the underwater moving target. The frequency of buoyancy in water. The constant speed for underwater moving targets.

[0083] Step 12: Based on the analytical solution of the three-dimensional flow field of the source-induced internal wave and the background sound velocity, calculate the disturbance sound velocity profile at each time moment, and then add it to the background sound velocity to obtain the total sound velocity profile at each time moment.

[0084] In practical implementation, after obtaining the analytical solution of the three-dimensional flow field of the source-induced internal wave, the disturbance sound velocity profile at each moment can be calculated based on the analytical solution of the three-dimensional flow field of the source-induced internal wave and the background sound velocity. Then, by adding the background sound velocity (background sound velocity profile), the total sound velocity profile at each moment can be obtained.

[0085] Understandably, source-induced internal waves disturb the local flow field, leading to fluctuations in fluid density and sound velocity, thus affecting the observation point. The speed of sound at a disturbance point is defined as This process occurs in the time domain. Discretize the time interval (this time interval should not be less than the sound propagation time between the sound source and the receiver), then the observation point The first The perturbation sound velocity profile at time t can be expressed by the formula:

[0086] ;

[0087] in, Background sound velocity profile For marine environmental constants, The frequency of buoyancy in water. For observation point The first The three-dimensional vertical amplitude of the source internal wave field at time t. For observation point The first The perturbation speed profile at any given moment.

[0088] If the total sound velocity profile under the influence of the source-induced internal wave is considered as the sum of the background sound velocity profile and the disturbance sound velocity profile, then the observation point... The first The total sound velocity profile at time t is expressed by the formula:

[0089] ;

[0090] in, For observation point The first The total sound velocity profile at any given time.

[0091] Step 13: Based on the background sound velocity, determine the channel conditions under passive internal wave action, and then based on the total sound velocity profile, determine the channel conditions under active internal wave action.

[0092] In practical implementation, after calculating the total sound velocity profile, it is necessary to determine the channel conditions under passive internal wave action based on the background sound velocity (background sound velocity profile), and then determine the channel conditions under active internal wave action based on the total sound velocity profile.

[0093] In one example, the sound field The overall sound field can be decomposed into the background sound field. The superposition of the sound field induced by passive internal waves and the sound field induced by source internal waves. , is represented as: In the case of passive internal wave generation, .

[0094] The channel conditions under passive induced internal wave action can be expressed by the Helmholtz-Kirchhoff equation as follows:

[0095] ;

[0096] in, yes The abbreviation for observation point Undisturbed background density at that location This indicates calculating the gradient. Indicates the location of the sound source. yes The abbreviation for Green's function indicates the background function. For the frequency of the sound source, Let be the impulse function of the sound source. Background sound velocity profile.

[0097] The Helmholtz-Kirchhoff equations (integral equations) are a core mathematical tool in wave theory, used to describe how, under given boundary conditions, the wave field (e.g., sound field, light field, seismic wave field, etc.) at any point in space is determined by the field values ​​and their normal derivatives at that boundary. Derived from Green's theorem, the Helmholtz-Kirchhoff equations form the basis for analyzing diffraction, scattering, and wave propagation problems.

[0098] Under the influence of source-induced internal waves, the medium density and sound velocity are considered as a superposition of background and local disturbances, resulting in anomalies in the corresponding channel acoustic transmission characteristics and the total Green's function. Decomposed into , yes abbreviation, yes , a shorthand for the perturbation Green's function.

[0099] The channel condition under active internal wave action is expressed as:

[0100] ;

[0101] in, yes The abbreviation for observation point The background density of the disturbance at that location That is, the observation point Total background density at the location, , yes The abbreviation for observation point The first The total sound velocity profile at any given moment. yes The abbreviation for observation point The first The perturbation speed profile at any given moment.

[0102] Step 14: Based on the channel conditions under passive internal wave action and active internal wave action, calculate the perturbation Green's function, and based on the perturbation Green's function and the sound source spectrum, calculate the sound field induced by the source internal wave.

[0103] In practical implementation, after determining the channel conditions under passive induced internal wave action and the channel conditions under active induced internal wave action, the perturbation Green's function can be calculated based on the channel conditions under passive induced internal wave action and the channel conditions under active induced internal wave action, and the source-induced internal wave-induced sound field can be calculated based on the perturbation Green's function and the sound source spectrum.

[0104] In one example, this embodiment subtracts the channel conditions under active internal wave action from those under passive internal wave action, considering only the change in the Green's function between the sound source and the receiver under small perturbations, and calculates the perturbation Green's function. , Represented as:

[0105] ;

[0106] ;

[0107] in, For the observation point, Indicates the location of the sound source. express and The position between, express and The space between As a sound pressure field sensitive core, for and The angle between them for and The angle between them for Background sound velocity profile at that location. for The velocity profile of the disturbance at that location. for Undisturbed background density at that location for The background density of the disturbance at that location.

[0108] Finally, this embodiment calculates the source-induced internal wave sound field based on the perturbation Green's function and the sound source spectrum using the following formula. :

[0109] ;

[0110] in, The motion time of an underwater moving target. The sound source spectrum, It is the imaginary unit.

[0111] Step 15: Based on the calculated source-induced internal wave induced sound field, perform source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis, and parameter optimization.

[0112] In practical implementation, after calculating the source-induced internal wave induced sound field, the source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis and parameter optimization can be carried out based on the calculated source-induced internal wave induced sound field.

[0113] In one example, based on the calculated source-induced internal wave-induced sound field, we can conduct an acoustic effect mechanism analysis. By comparing the spatial distribution, propagation path, and time-frequency characteristic changes of the sound field under different internal wave structures (such as modes, amplitudes, propagation directions, etc.), we can reveal how internal waves modulate sound wave propagation, identify key physical processes (such as focusing / defocusing, multipath interference, sound velocity profile perturbation, etc.), and thus establish the physical relationship between internal wave parameters and the sound field response. Next, we perform sensitivity analysis to quantify the influence of each internal wave parameter (such as frequency, wavenumber, initial phase, etc.) on sound field characteristics (such as propagation loss, arrival time, signal distortion, etc.). Typically, the controlled variable method or global sensitivity method is used to assess which parameters dominate the acoustic response, providing a basis for subsequent model simplification or observation focus. Finally, based on the understanding of the mechanism and the results of sensitivity analysis, parameter optimization is carried out. With specific acoustic performance indicators (such as maximizing the signal-to-noise ratio and minimizing the positioning error) as the objective function, optimization algorithms (such as genetic algorithms and gradient descent) are used to invert or adjust the configuration of internal wave-related parameters. This enables active control of the sound field characteristics or the design of the optimal perception strategy for the internal wave environment, thereby improving the robustness and adaptability of the underwater acoustic system in the internal wave environment.

[0114] This embodiment proposes a rapid calculation method for source-induced internal wave-induced sound field under typical shallow sea strata conditions. The underwater moving target is simplified to an ideal sphere, and a three-dimensional vertical displacement field is established using the analytical theory of source-induced internal waves. The density and sound velocity disturbances caused by internal waves are mapped to time-varying acoustic parameter disturbances. Under a first-order approximation, the acoustic wave equation is decomposed into background and anomaly terms, and a first-order perturbation update formula based on background sound rays is constructed to achieve rapid updates of the channel Green's function and multipath delay / amplitude, ultimately obtaining the spatiotemporal distribution of the induced sound field. This method follows a unidirectional coupling framework of "target, flow field, and sound field," significantly reducing computational resource consumption and improving computational efficiency, thus facilitating the analysis of the acoustic effect mechanism, sensitivity analysis, and parameter optimization of source-induced internal waves.

[0115] The steps described above are merely for clarity in describing the technical solution. In actual implementation, they can be combined into one step, or certain steps can be broken down into multiple steps, as long as they involve the same logical relationship, they are all within the scope of protection of this application. Any insignificant modifications or designs added to the algorithm or process, as long as they do not change the core of the algorithm or process, are also within the scope of protection of this application.

[0116] In one example, to verify the effectiveness of the proposed method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling, we conducted relevant simulation experiments.

[0117] Simulation conditions were set up based on a typical shallow sea environment, with a water depth of 100m, a stratified center depth of 40m and a thickness of 40m, and density stratification. The vertical distribution of density stratification and buoyancy frequency is as follows. Figure 3 The two black dashed lines indicate this. Note that this application follows the principle of "one-way coupling of target, flow field, and sound field," and does not consider the reverse effect of the sound field on the flow field or target. It is suitable for rapid evaluation of the general laws of source-induced internal wave acoustic effects. A spherical target with a radius of 4 m moves in a straight line at a constant speed of 2 m / s (approximately 4 kN) at a depth of 40 m. The three-dimensional field of source-induced internal waves excited by the target is simulated, and the distribution of internal waves on horizontal cross-sections at different depths is given. These cross-sections are all parallel to the target's motion plane and are located at different vertical distances relative to the target's depth. The results are as follows: Figure 4 As shown. Figure 4 The results from left to right at the top are 5m, 10m, and 20m (above the target), and the results from left to right at the bottom are -5m, -10m, and -20m (below the target). The internal wave amplitude exhibits alternating high and low amplitude regions along the X-axis. At the same relative depth, the internal wave wavelength structure and amplitude are highly symmetrical, resulting in identical spatial structures of the source internal wave field, but with completely opposite amplitude distributions.

[0118] Typical sound velocity profile of a shallow sea in summer with a strata such as Figure 5 As shown, the sound velocity in the upper and lower layers is relatively stable, while the sound velocity in the central depth layer fluctuates drastically. When the target passes through the detection area of ​​the transmitter-receiver line at a constant velocity perpendicularly, the residual source-induced internal waves can cause fluctuations in the sound velocity profile on the vertical plane where the transmitter-receiver line is located at different times. The "snapshot" results of the sound velocity profile are as follows: Figure 6 As shown. Figure 6 The upper left and right measurements are 100s, 300s, and 500s, respectively, while the lower left and right measurements are 700s, 900s, and 1000s. The sound velocity contour lines at the crossing point show a significant vertical displacement shortly after the source-induced internal wave enters the detection area, expanding horizontally over time while gradually decreasing in amplitude. As time exceeds 700s (the target has moved 1.4 km away), the sound velocity disturbance becomes more diffuse, and the disturbance amplitude dissipates synchronously with the internal wave energy, returning to background levels around 1000s (the target has moved 2 km away).

[0119] Figure 7 The upper and lower halves of the figures represent the sound propagation loss with and without active internal wave perturbation, respectively. Without internal waves, the sound field exhibits a clear pattern of alternating "bright areas" (low propagation loss) and "dark areas" (high propagation loss) formed by multipath interference, with relatively lower propagation loss at the same depth as the sound source. After active internal wave perturbation, the original propagation loss interference distribution changes significantly, and the irregular convergence of sound energy forms new transmission paths, continuously influencing the sound field at greater distances as the sound propagates.

[0120] The change in the forward sound pressure field induced by the source-induced internal wave is obtained by subtracting the sound pressure field under the action of the internal wave from the background sound field. The change in induced sound field intensity is obtained by taking the absolute value of the sound pressure change and normalizing it logarithmically. The results are as follows: Figure 8 As shown, the overall structure of the induced sound field is consistent with the background multipath propagation. Strong sound pressure variation bands propagate forward along several specific trajectories, corresponding to different intrinsic sound beams. These bands intersect, converge, or diverge during propagation, forming complex spatial interference patterns. In regions with sparse sound beams or inherently weak energy, even the presence of internal waves results in relatively small induced sound pressure variations. The calculation time for the flow-coupled sound field at a single moment is 1.5 minutes, which is much faster than that of the finite element model.

[0121] Another embodiment of this application proposes a fast calculation system for source-induced internal wave sound field of stream-sound coupling. The details of the fast calculation system for source-induced internal wave sound field of stream-sound coupling proposed in this embodiment are described in detail below. The following content is only provided for the convenience of understanding and is not necessary for implementing this solution. Figure 9 This is a schematic diagram of the structure of a fast calculation system for source-induced internal wave sound field based on flow-sound coupling proposed in this embodiment, including: a model establishment module 21, a sound velocity profile calculation module 22, a channel condition determination module 23, a source-induced internal wave sound field calculation module 24, and an application module 25.

[0122] Model building module 21 is used to sequentially build a layered marine environment, the required coordinate system and target motion model for underwater moving targets, and calculate the analytical solution of the source-induced internal wave three-dimensional flow field.

[0123] The sound velocity profile calculation module 22 is used to calculate the disturbance sound velocity profile at each moment based on the analytical solution of the three-dimensional flow field of the source-induced internal wave and the background sound velocity, and then add it to the background sound velocity to obtain the total sound velocity profile at each moment.

[0124] The channel condition determination module 23 is used to determine the channel conditions under passive internal wave action based on the background sound speed, and then determine the channel conditions under active internal wave action based on the total sound speed profile.

[0125] The source-induced internal wave induced sound field calculation module 24 is used to calculate the perturbation Green's function based on the channel conditions under passive internal wave action and the channel conditions under active internal wave action, and to calculate the source-induced internal wave induced sound field based on the perturbation Green's function and the sound source spectrum.

[0126] Application module 25 is used to perform source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis and parameter optimization based on the calculated source-induced internal wave induced sound field.

[0127] It is worth noting that all modules involved in this embodiment are logical modules. In practical applications, a logical module can be a physical module, a part of a physical module, or an organic combination of multiple physical modules. Furthermore, to highlight the innovative aspects of this application, this embodiment does not introduce modules that are not closely related to solving the technical problems proposed in this application. However, this does not mean that other modules are absent from this embodiment.

[0128] It is not difficult to see that this embodiment is a system embodiment corresponding to the above method embodiments, and this embodiment can be implemented in conjunction with the above method embodiments. The relevant technical details and technical effects mentioned in the above method embodiments are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the above method embodiments.

[0129] Another embodiment of this application provides an electronic device, such as Figure 10 As shown, it includes a processor 31 and a memory 32. The memory 32 stores instructions that the processor 31 can execute. When the processor 31 is configured to execute the instructions, the electronic device can realize a method for rapid calculation of source-induced internal wave sound field by flow-sound coupling as described in the above method embodiment.

[0130] The memory and processor are connected via a bus, which includes any number of interconnecting buses and bridges, connecting various circuits of one or more processors and the memory. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0131] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0132] Another embodiment of this application proposes a computer-readable storage medium storing a computer program that, when executed by a processor, enables a method for rapid calculation of source-induced internal wave sound field in flow-acoustic coupling as described in the above method embodiments.

[0133] That is, those skilled in the art will understand that all or part of the steps in the above method embodiments can be implemented by a program instructing related hardware. The program is stored in a storage medium and includes several instructions to cause a device (such as a microcontroller, chip, etc.) or processor to execute all or part of the steps of the method described in the method embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.

[0134] It will be understood by those skilled in the art that the above embodiments are specific implementations of this application, and various changes in form and detail can be made in practical applications without departing from the spirit and scope of this application. For those skilled in the art, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A method for rapid calculation of source-induced internal wave sound field in flow-acoustic coupling, characterized in that, include: For underwater moving targets, a layered marine environment, the required coordinate system, and the target motion model are established sequentially, and the analytical solution of the three-dimensional flow field of the source-induced internal wave is calculated. Based on the analytical solution of the three-dimensional flow field of the source-induced internal wave and the background sound velocity, the perturbation sound velocity profile at each time moment is calculated, and then added to the background sound velocity to obtain the total sound velocity profile at each time moment. Based on the background sound velocity, the channel conditions under passive internal wave action are determined, and then based on the total sound velocity profile, the channel conditions under active internal wave action are determined. Based on the channel conditions under passive internal wave action and active internal wave action, the perturbation Green's function is calculated, and based on the perturbation Green's function and the sound source spectrum, the sound field induced by the active internal wave is calculated. Based on the calculated source-induced internal wave induced sound field, we conduct source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis and parameter optimization; The process of establishing a layered marine environment, the required coordinate system, and the target motion model for underwater moving targets includes: Establish a Cartesian coordinate system in a flat seabed and a three-dimensional computational domain. ;in, , , These represent the x-coordinate, y-coordinate, and vertical coordinate of the Cartesian coordinate system, respectively. With the underwater moving target as the origin, the negative direction of the underwater moving target's heading as the positive X-axis, and the sea surface direction as the positive Z-axis, a body coordinate system is established according to the right-hand rule. ;in, Represents the x-coordinate of the volume coordinate system. , For a constant speed of movement of an underwater target, For the motion time of the underwater moving target, the vertical coordinates of the body coordinate system are the same as those of the Cartesian coordinate system; Establish a spherical coordinate system ;in, , , These represent the radial distance, pitch angle, and azimuth angle in spherical coordinates, respectively. , , ; Given background density and background sound velocity profile ,based on and Calculate the buoyancy frequency of the water body ; The underwater moving target is simplified to a radius of... An ideal sphere, with a center depth of . At the initial position Maintaining a constant speed According to the heading angle in the horizontal plane Linear motion, motion time is The target motion model of an underwater moving target can then be represented as: ； in, A target motion model representing an underwater moving target; The analytical solution for the three-dimensional flow field of the source-induced internal wave includes: The three-dimensional vertical amplitude of the source-induced internal wave field is calculated using the following formula, based on the analytical solution of the source-induced internal wave from a slowly moving spherical target: ； ； ； ； in, For the Heaviside function, Indicates the observation point. That is, the observation point The three-dimensional vertical amplitude of the source-induced internal wave field at the location, For the amplitude term, It is a first-order spherical Bessel function. For phase terms, Let be the radius of the underwater moving target. The frequency of buoyancy in water. The constant speed for underwater moving targets.

2. The method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling as described in claim 1, characterized in that, The method involves calculating the disturbance sound velocity profile at each moment based on the analytical solution of the three-dimensional flow field caused by the source internal wave and the background sound velocity, and then adding it to the background sound velocity to obtain the total sound velocity profile at each moment, including: Internal waves can disturb the local flow field, leading to fluctuations in fluid density and sound velocity, thus affecting the observation point. The speed of sound at a disturbance point is defined as This process occurs in the time domain. If the time interval is discretized, then the observation points The first The perturbation sound velocity profile at time t is expressed by the formula: ； in, Background sound velocity profile For marine environmental constants, The frequency of buoyancy in water. For observation point The first The three-dimensional vertical amplitude of the source internal wave field at time t. For observation point The first The velocity profile of the disturbance at any given moment; If the total sound velocity profile under the influence of the source-induced internal wave is considered as the sum of the background sound velocity profile and the disturbance sound velocity profile, then the observation point... The first The total sound velocity profile at time t is expressed by the formula: ； in, For observation point The first The total sound velocity profile at any given time.

3. The method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling as described in claim 2, characterized in that, The determination of channel conditions under passive internal wave action based on background sound speed includes: The channel condition under passive induced internal wave action is expressed by the Helmholtz-Kirchhoff equation as follows: ； in, yes The abbreviation for observation point Undisturbed background density at that location This indicates calculating the gradient. Indicates the location of the sound source. yes The abbreviation for Green's function indicates the background function. For the frequency of the sound source, Let be the impulse function of the sound source. Background sound velocity profile.

4. The method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling as described in claim 3, characterized in that, The determination of channel conditions under active internal wave action based on the total sound velocity profile includes: Under the influence of source-induced internal waves, the medium density and sound velocity are considered as a superposition of background and local disturbances, resulting in anomalies in the corresponding channel acoustic transmission characteristics and the total Green's function. Decomposed into , yes abbreviation, yes The abbreviation for Green's function is used to represent the perturbation function. The channel condition under active internal wave action is expressed as: ； in, yes The abbreviation for observation point The background density of the disturbance at that location That is, the observation point Total background density at the location, , yes The abbreviation for observation point The first The total sound velocity profile at any given moment. yes The abbreviation for observation point The first The perturbation speed profile at any given moment.

5. The method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling as described in claim 4, characterized in that, The calculation of the perturbation Green's function based on the channel conditions under passive induced internal wave action and the channel conditions under active induced internal wave action includes: The perturbation Green's function is calculated by subtracting the channel conditions under active internal wave action from those under passive internal wave action. , Represented as: ； ； in, For the observation point, Indicates the location of the sound source. express and The position between, express and The space between As a sound pressure field sensitive core, for and The angle between them for and The angle between them for Background sound velocity profile at that location. for The velocity profile of the disturbance at that location. for Undisturbed background density at that location for The background density of the disturbance at that location; The sound field induced by source-induced internal waves is calculated based on the perturbation Green's function and the sound source spectrum. This can be achieved through the following formula: ； in, The motion time of an underwater moving target. The sound source spectrum, It is the imaginary unit.

6. A fast calculation system for source-induced internal wave sound field in a flow-acoustic coupling system, characterized in that, include: The model building module is used to sequentially build a layered marine environment, the required coordinate system, and the target motion model for underwater moving targets, and to calculate the analytical solution of the three-dimensional flow field of the source-induced internal wave. The sound velocity profile calculation module is used to calculate the disturbance sound velocity profile at each moment based on the analytical solution of the three-dimensional flow field of the source-induced internal wave and the background sound velocity, and then add it to the background sound velocity to obtain the total sound velocity profile at each moment. The channel condition determination module is used to determine the channel conditions under passive internal wave action based on the background sound velocity, and then determine the channel conditions under active internal wave action based on the total sound velocity profile. The source-induced internal wave induced sound field calculation module is used to calculate the perturbation Green's function based on the channel conditions under passive and active internal wave action, and to calculate the source-induced internal wave induced sound field based on the perturbation Green's function and the sound source spectrum. The application module is used to perform source-induced internal wave acoustic effect mechanism analysis, sensitivity analysis and parameter optimization based on the calculated source-induced internal wave induced sound field; The process of establishing a layered marine environment, the required coordinate system, and the target motion model for underwater moving targets includes: Establish a Cartesian coordinate system in a flat seabed and a three-dimensional computational domain. ;in, , , These represent the x-coordinate, y-coordinate, and vertical coordinate of the Cartesian coordinate system, respectively. With the underwater moving target as the origin, the negative direction of the underwater moving target's heading as the positive X-axis, and the sea surface direction as the positive Z-axis, a body coordinate system is established according to the right-hand rule. ;in, Represents the x-coordinate of the body coordinate system. , For a constant speed of movement of an underwater target, For the motion time of the underwater moving target, the vertical coordinates of the body coordinate system are the same as those of the Cartesian coordinate system; Establish a spherical coordinate system ;in, , , These represent the radial distance, pitch angle, and azimuth angle in spherical coordinates, respectively. , , ; Given background density and background sound velocity profile ,based on and Calculate the buoyancy frequency of the water body ; The underwater moving target is simplified to a radius of... An ideal sphere, with a center depth of . At the initial position Maintaining a constant speed According to the heading angle in the horizontal plane Linear motion, motion time is The target motion model of an underwater moving target can then be represented as: ； in, A target motion model representing an underwater moving target; The analytical solution for the three-dimensional flow field of the source-induced internal wave includes: The three-dimensional vertical amplitude of the source-induced internal wave field is calculated using the following formula, based on the analytical solution of the source-induced internal wave from a slowly moving spherical target: ； ； ； ； in, For the Heaviside function, Indicates the observation point. That is, the observation point The three-dimensional vertical amplitude of the source-induced internal wave field at the location, For the amplitude term, It is a first-order spherical Bessel function. For phase terms, Let be the radius of the underwater moving target. The frequency of buoyancy in water. The constant speed for underwater moving targets.

7. An electronic device, characterized in that, include: A processor and a memory, wherein the memory stores instructions that the processor can execute, and the processor is configured to, when executing the instructions, enable the electronic device to implement a method for rapid calculation of source-induced internal wave sound field by flow-acoustic coupling as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it can realize a method for rapid calculation of source-induced internal wave sound field of flow-acoustic coupling as described in any one of claims 1 to 5.

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