Bubble pulsation initial condition inversion method and system based on bubble energy loss target

Abstract

The invention relates to the field of theoretical calculation and numerical simulation of ship structure protection and cavitation, in particular to a bubble pulsation initial condition inversion method and system based on a bubble energy loss target. Inputting characteristic parameters and energy parameters of the bubbles, and determining a target variable value of inversion calculation; taking a bubble maximum volume moment as an initial calculation moment, randomly giving a bubble internal pressure value at the bubble maximum volume moment, and determining a bubble initial condition in inversion calculation; reversely carrying out time integration on the basis of a compressible spherical bubble pulsation equation to obtain bubble characteristic parameters at zero moment; calculating a time calendar evolution process of a bubble radius by taking a bubble characteristic parameter obtained by reverse time integration as a bubble pulsation initial condition, and judging whether the energy loss of the bubble reaches a target value or not; and adjusting the bubble internal pressure value at the moment of the maximum volume of the bubbles for re-calculation, solving a bubble radius time calendar process, and recording bubble characteristic parameters after reaching an expected target as a new bubble pulsation initial condition. The method is used for solving the problem that the initial bubble pulsation condition is difficult to determine in the existing bubble dynamics theory and numerical calculation.

Description

Technical Field

[0001] The invention relates to the field of theoretical calculation and numerical simulation of ship structure protection and cavitation, and is a bubble pulsation initial condition inversion method based on a bubble energy loss target and a system thereof. Background Art

[0002] Pulsating bubbles are widely present in nature and engineering applications. In recent decades, a large number of bubble dynamics theories and numerical simulation methods have been vigorously developed. Theoretical and numerical results are important means to scale experimental systems and reveal the mechanism of bubble dynamics. However, in the theoretical calculation and numerical simulation process of bubble dynamics, the initial conditions of bubble pulsation have always been an important problem that has troubled researchers. For applications such as underwater explosions and high-pressure air guns, researchers have developed targeted empirical formulas for the initial conditions of bubble pulsation, such as bubbles generated by standard TNT explosives. However, in actual applications, the bubbles generated in engineering in most cases have great randomness and uncertainty, which results in large errors when using theoretical calculations or numerical simulations to reproduce experimental results, and it is impossible to accurately scale the experimental system or reveal the mechanical mechanism. Therefore, the study and determination of the initial conditions of underwater pulsating bubbles is very important for both engineering applications and basic scientific research.

[0003] There are many sources of underwater bubbles. The dynamic characteristics of bubbles generated by different methods and under different conditions are different, which greatly increases the difficulty of determining the initial conditions of bubble pulsation. The bubble initial condition inversion method based on the target result can well avoid the calculation uncertainty caused by different bubble sources. The bubble pulsation process is affected by many physical factors such as fluid compressibility, boundary effects and flow field environment. The most significant impact of these factors on the dynamic characteristics of bubbles is reflected in the energy loss of bubbles, that is, the maximum volume ratio of two adjacent cycles of bubbles. Based on this target result, the initial condition of the bubble is inverted and calculated to obtain a new initial condition for bubble pulsation. The calculation result matches the target result to the greatest extent, realizing the accurate reproduction of the bubble pulsation time history process under different conditions, so as to be applied to basic scientific research and engineering practice in bubble-related fields.

[0004] The existing technology often uses some existing empirical formulas to determine the initial conditions of bubble pulsation when conducting theoretical calculations and numerical simulations to compare with experimental results. However, this approach cannot achieve a high degree of consistency between the calculated results and the experimental results in most cases, especially in the bubble rebound stage. The deviation poses a great challenge to basic scientific research and experimental design. For this goal, determining the initial conditions of bubbles based on the bubble energy loss target has great advantages. Summary of the invention

[0005] The present invention provides a bubble pulsation initial condition inversion method based on a bubble energy loss target, which solves the problem that the initial conditions of bubble pulsation are difficult to determine in existing bubble dynamics theory and numerical calculation.

[0006] The present invention provides a bubble pulsation initial condition inversion system based on a bubble energy loss target, which is used to implement a bubble pulsation initial condition inversion method based on a bubble energy loss target.

[0007] The present invention is achieved through the following technical solutions:

[0008] A bubble pulsation initial condition inversion method based on a bubble energy loss target, the inversion method comprising the following steps:

[0009] Step 1: input the characteristic parameters and energy parameters of the bubble and determine the target variable value of the inversion calculation;

[0010] Step 2, taking the moment of maximum bubble volume as the initial calculation moment, arbitrarily giving a bubble internal pressure value at the moment of maximum bubble volume, and determining the initial condition of the bubble in the inversion calculation;

[0011] Step 3, based on the compressible spherical bubble pulsation equation, reverse time integration is performed to obtain the bubble characteristic parameters at time zero;

[0012] Step 4, using the bubble characteristic parameters obtained by reverse time integration as the initial conditions of bubble pulsation, calculating the time evolution process of the bubble radius, and judging whether the energy loss of the bubble has reached the target value;

[0013] Step 5, adjust the bubble internal pressure value at the moment of maximum bubble volume in step 2 and recalculate, solve the bubble radius time history process, record the bubble characteristic parameters after reaching the expected target, and use them as new bubble pulsation initial conditions.

[0014] Furthermore, in the step 1, characteristic parameters and energy parameters of the bubble are input, including the time corresponding to the maximum volume of the bubble, the maximum radius of the bubble in the first cycle, and the maximum radius of the bubble in the second cycle, to determine the energy loss value of the bubble;

[0015] In step 1, the energy ratio of the bubble in the first two pulsation cycles can be calculated as follows:

[0016]

[0017] Where E f and E s are the energy of the first and second cycles of the bubble, R maxf and R maxs are the maximum radii of the first and second cycles of the bubble, respectively.

[0018] Furthermore, in step 2, the maximum volume moment of the bubble in the first cycle is taken as the initial calculation moment, at which the pulsation speed of the bubble is zero. For any given bubble internal pressure value at the maximum volume moment, this patent takes it as one percent of the hydrostatic pressure at the location of the bubble, so the initial condition of the bubble in the inversion calculation can be determined as follows:

[0019]

[0020] Where R 0 is the radius of the bubble at the initial calculation time, is the pulsation velocity of the bubble at the initial calculation time, P 0 is the initial internal pressure of the bubble, P ∞ is the hydrostatic pressure at the bubble location.

[0021] Furthermore, in step 3, the compressible spherical bubble pulsation equation is used to perform time integration in reverse, and the initial moment is the moment of maximum bubble volume. The compressible bubble pulsation equation adopts the following equation:

[0022]

[0023] Where R is the bubble radius at any time, and are the first-order time derivative and the second-order time derivative of the bubble radius, C is the sound velocity of the flow field, H is the enthalpy difference on the bubble surface, is the first time derivative of the enthalpy difference;

[0024] In step 3, the enthalpy difference on the bubble surface is calculated using the adiabatic equation:

[0025]

[0026] Among them, ρ is the density of the fluid in the flow field, and κ is the gas adiabatic coefficient.

[0027] Furthermore, in step 3, the bubble parameters in formula (2) are used as initial conditions, and the fourth-order Runge-Kutta method is used to perform reverse time advancement on formula (3) to calculate the bubble radius change process, and the bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at time zero are obtained, which are used as new bubble pulsation initial conditions, respectively denoted as R n0 , and P n0 .

[0028] Furthermore, in step 4, the time evolution of the bubble radius is calculated using the new initial conditions for bubble pulsation, with the initial time being time zero, to obtain a new bubble energy loss value, and the energy magnitudes of the first and second cycles of the bubble in the calculation are respectively recorded as E nf and E ns ;

[0029] Determine whether the energy loss value of the bubble has reached the target value. When the error between the calculated energy loss value of the bubble and the target value is within 3%, it is considered that the target has been reached, that is, it is determined according to the following formula:

[0030]

[0031] If the calculation result satisfies formula (5), R n0 , and P n0 As the final initial condition of bubble pulsation, it is used to carry out theoretical or numerical analysis in engineering and basic scientific research without the need for subsequent steps.

[0032] Furthermore, in step 5, if the calculation result in step 4 does not satisfy formula (5), it means that the internal pressure at the moment of maximum bubble volume deviates from the target working condition, and it is necessary to return to step 2 to adjust the bubble internal pressure value at the moment of maximum bubble volume, and then use formula (3) to calculate the bubble radius, pulsation velocity absolute value and bubble internal pressure at time zero again;

[0033] The adjustment of the bubble internal pressure value at the moment of maximum bubble volume needs to be considered based on the calculation results in step 4;

[0034] The bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at the zero time in the recalculation are used as the initial conditions of the bubble pulsation. Formula (3) is used to calculate the change process of the bubble radius to determine whether the energy loss value of the bubble reaches the target value. This cycle is repeated until formula (5) is satisfied.

[0035] The final equation (5) is recorded to obtain the bubble radius, pulsation velocity and bubble internal pressure that satisfy the post-zero time, which is used as the initial condition of bubble pulsation to serve the theoretical and numerical simulation in engineering applications and basic scientific research.

[0036] A bubble pulsation initial condition inversion system based on a bubble energy loss target, the inversion system using the bubble pulsation initial condition inversion method based on a bubble energy loss target as described above, the inversion system comprising:

[0037] The target variable value determination module inputs the characteristic parameters and energy parameters of the bubble to determine the target variable value of the inversion calculation;

[0038] The bubble initial condition determination module takes the moment of maximum bubble volume as the initial calculation moment, and arbitrarily gives a bubble internal pressure value at the moment of maximum bubble volume to determine the bubble initial condition in the inversion calculation;

[0039] The bubble characteristic parameter acquisition module at time zero performs reverse time integration based on the compressible spherical bubble pulsation equation to obtain the bubble characteristic parameters at time zero;

[0040] Step 4, using the bubble characteristic parameters obtained by reverse time integration as the initial conditions of bubble pulsation, calculating the time evolution process of the bubble radius, and judging whether the energy loss of the bubble has reached the target value;

[0041] Step 5, adjust the bubble internal pressure value at the moment of maximum bubble volume in step 2 and recalculate, solve the bubble radius time history process, record the bubble characteristic parameters after reaching the expected target, and use them as new bubble pulsation initial conditions.

[0042] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the above method is implemented.

[0043] A computer-readable storage medium stores a computer program, and the computer program implements the above method when executed by a processor.

[0044] The beneficial effects of the present invention are:

[0045] The present invention will inversely calculate the initial conditions of bubble pulsation based on the energy loss value of the bubble, and propose a method for determining the initial conditions of underwater pulsating bubbles that is suitable for any environmental conditions. This will solve the problem that the theoretical and numerical calculation results in existing bubble dynamics research cannot accurately reproduce the target results, and achieve the purpose of accurately predicting the initial conditions of bubble pulsation under any conditions, providing technical support for related basic scientific research on bubble dynamics. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of the method of the present invention.

[0047] Figure 2 It is an explanatory diagram of the principle of the bubble pulsation initial condition inversion method in the present invention.

[0048] Figure 3 It is an explanatory diagram of the effect of internal pressure on bubble energy loss at the moment of maximum bubble volume in the present invention.

[0049] Figure 4 It is a calculation effect diagram of the initial conditions obtained by the inversion method in the present invention. DETAILED DESCRIPTION

[0050] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0051] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0052] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0053] The following is attached to this application specification Figure 1-4 , the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0054] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0055] Implementation Method 1

[0056] This embodiment provides, according to Figure 1 A bubble pulsation initial condition inversion method based on a bubble energy loss target is shown, and the inversion method comprises the following steps:

[0057] Step 1: input the characteristic parameters and energy parameters of the bubble and determine the target variable value of the inversion calculation;

[0058] Step 2, taking the moment of maximum bubble volume as the initial calculation moment, arbitrarily giving a bubble internal pressure value at the moment of maximum bubble volume, and determining the initial condition of the bubble in the inversion calculation;

[0059] Step 3, based on the compressible spherical bubble pulsation equation, reverse time integration is performed to obtain the bubble characteristic parameters at time zero;

[0060] Step 4, using the bubble characteristic parameters obtained by reverse time integration as the initial conditions of bubble pulsation, calculating the time evolution process of the bubble radius, and judging whether the energy loss of the bubble has reached the target value;

[0061] Step 5, adjust the bubble internal pressure value at the moment of maximum bubble volume in step 2 and recalculate, solve the bubble radius time history process, record the bubble characteristic parameters after reaching the expected target, and use them as new bubble pulsation initial conditions.

[0062] Furthermore, in step one, characteristic parameters and energy parameters of the bubble are input, including the time corresponding to the maximum volume of the bubble, the maximum radius of the bubble in the first cycle, and the maximum radius of the bubble in the second cycle, to determine the energy loss value of the bubble.

[0063] Furthermore, in step 1, the target value of the energy loss of the bubble is quantified by the ratio of the energy of the bubble in the first two pulsation cycles. The energy of the bubble is proportional to the volume, so the ratio of the energy of the bubble in the first two pulsation cycles can be calculated as follows:

[0064]

[0065] Where E f and E s are the energy of the first and second cycles of the bubble, R maxf and R maxs are the maximum radii of the first and second cycles of the bubble, respectively.

[0066] Furthermore, in step 2, the moment of maximum volume of the bubble in the first period is taken as the initial calculation moment, at which the pulsation speed of the bubble is zero. For any given bubble internal pressure value at the moment of maximum volume of the bubble, the present invention takes it as 1% of the hydrostatic pressure at the location of the bubble, so the initial condition of the bubble in the inversion calculation can be determined as follows:

[0067]

[0068] Where R 0 is the radius of the bubble at the initial calculation time, is the pulsation velocity of the bubble at the initial calculation time, P 0 is the initial internal pressure of the bubble, P ∞ is the hydrostatic pressure at the bubble location.

[0069] Furthermore, in step 3, since the pulsation process of the bubble has a strong symmetry, taking the moment of the maximum bubble radius as the initial moment, the forward and reverse calculations along the time axis can obtain consistent bubble characteristic parameters, such as Figure 2 As shown, therefore, the compressible spherical bubble pulsation equation is used to reverse the time integration, the initial moment is the moment of maximum bubble volume, and the compressible bubble pulsation equation adopts the following equation:

[0070]

[0071] Where R is the bubble radius at any time, and are the first-order time derivative and the second-order time derivative of the bubble radius, C is the sound velocity of the flow field, H is the enthalpy difference on the bubble surface, is the first time derivative of the enthalpy difference.

[0072] Furthermore, in step 3, the enthalpy difference on the bubble surface is calculated using the adiabatic equation:

[0073]

[0074] Among them, ρ is the density of the fluid in the flow field, and κ is the gas adiabatic coefficient.

[0075] Furthermore, in step 3, the bubble parameters in equation (2) are used as initial conditions, and the fourth-order Runge-Kutta method is used to perform reverse time advancement on equation (3) to calculate the bubble radius change process, and the bubble radius, the absolute value of the pulsation velocity, and the bubble internal pressure at time zero are obtained, which are used as new bubble pulsation initial conditions, denoted as R and R respectively. n0 , and P n0 .

[0076] Furthermore, in step 4, the time evolution of the bubble radius is calculated using the new initial conditions of bubble pulsation, with the initial time being time zero, to obtain a new bubble energy loss value, and the energy magnitudes of the first and second cycles of the bubble in the calculation are recorded as E nf and E ns .

[0077] Further, in step 4, it is determined whether the energy loss value of the bubble has reached the target value. When the error between the calculated energy loss value of the bubble and the target value is within 3%, it is considered that the target has been reached, that is, the determination is made according to the following formula:

[0078]

[0079] Furthermore, in step 4, if the calculation result satisfies formula (5), R n0 , and P n0As the final initial condition of bubble pulsation, it is used to carry out theoretical or numerical analysis in engineering and basic scientific research without the need for subsequent steps.

[0080] Furthermore, in step 5, if the calculation result in step 4 does not satisfy equation (5), it means that the internal pressure at the moment of maximum bubble volume deviates from the target working condition, because when the bubble radius and pulsation speed are constant, the energy loss of the bubble is only related to the dynamic parameter of the bubble internal pressure. The influence of the internal pressure at the moment of maximum bubble radius is as follows: Figure 3 As shown, it is necessary to return to step 2 to adjust the bubble internal pressure value at the moment of maximum bubble volume, and then use formula (3) to calculate the bubble radius, pulsation velocity absolute value and bubble internal pressure at time zero again.

[0081] Furthermore, in step 5, the adjustment of the bubble internal pressure value at the moment of maximum bubble volume needs to be considered according to the calculation result in step 4. Specifically, if the calculated bubble energy loss value is greater than the target value, the bubble internal pressure needs to be increased, otherwise the bubble internal pressure needs to be reduced. In the present invention, the adjustment range of the bubble internal pressure is set to 2% of the bubble internal pressure in the first reverse integral calculation.

[0082] Furthermore, in step five, the bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at the zero time in the recalculation are used as the initial conditions of the bubble pulsation, and the bubble radius change process is calculated using formula (3) to determine whether the energy loss value of the bubble reaches the target value. This cycle is repeated until formula (5) is satisfied.

[0083] Furthermore, in step 5, the final formula (5) is recorded to obtain the bubble radius, pulsation velocity and bubble internal pressure that satisfy the post-zero time, which is used as the initial condition of bubble pulsation to serve the theoretical and numerical simulation in engineering applications and basic scientific research. The effect diagram of theoretical calculation using the initial condition of bubble pulsation obtained by inversion calculation is as follows: Figure 4 As shown, the new initial conditions can well reproduce the target bubble energy loss value.

[0084] Specifically, the present invention performs an inverse calculation on the initial conditions of the bubble pulsation based on the energy loss value of the bubble, and proposes a method for determining the initial conditions of underwater pulsating bubbles that is applicable to any environmental conditions.

[0085] Implementation Method 2

[0086] This embodiment provides a bubble pulsation initial condition inversion system based on a bubble energy loss target. The inversion system uses the bubble pulsation initial condition inversion method based on a bubble energy loss target as described in Embodiment 1. The inversion system includes:

[0087] The target variable value determination module inputs the characteristic parameters and energy parameters of the bubble to determine the target variable value of the inversion calculation;

[0088] The bubble initial condition determination module takes the moment of maximum bubble volume as the initial calculation moment, and arbitrarily gives a bubble internal pressure value at the moment of maximum bubble volume to determine the bubble initial condition in the inversion calculation;

[0089] The bubble characteristic parameter acquisition module at time zero performs reverse time integration based on the compressible spherical bubble pulsation equation to obtain the bubble characteristic parameters at time zero;

[0090] A judgment module uses the bubble characteristic parameters obtained by reverse time integration as the initial conditions of bubble pulsation, calculates the time evolution process of the bubble radius, and judges whether the energy loss of the bubble has reached the target value;

[0091] The calculation and storage module adjusts the bubble initial condition determination module to recalculate the bubble internal pressure value at the moment of the bubble's maximum volume, solves the bubble radius time history process, and records the bubble characteristic parameters after reaching the expected target, which are used as new bubble pulsation initial conditions.

[0092] In the target variable value determination module, the characteristic parameters and energy parameters of the bubble are input, including the time corresponding to the maximum volume of the bubble, the maximum radius of the bubble in the first cycle, and the maximum radius of the bubble in the second cycle, to determine the energy loss value of the bubble.

[0093] Furthermore, in the target variable value determination module, the energy loss target value of the bubble is quantified by the ratio of the energy of the bubble in the first two pulsation cycles. The energy of the bubble is proportional to the volume, so the ratio of the energy of the bubble in the first two pulsation cycles can be calculated as follows:

[0094]

[0095] Where E f and E s are the energy of the first and second cycles of the bubble, R maxf and R maxs are the maximum radii of the first and second cycles of the bubble, respectively.

[0096] Furthermore, in the bubble initial condition determination module, the maximum volume moment of the bubble in the first period is taken as the initial calculation moment, at which the bubble pulsation speed is zero. For any given bubble internal pressure value at the maximum volume moment, the present invention takes it as one percent of the hydrostatic pressure at the location of the bubble, so the bubble initial condition in the inversion calculation can be determined as follows:

[0097]

[0098] Where R0 is the radius of the bubble at the initial calculation time, is the pulsation velocity of the bubble at the initial calculation time, P 0 is the initial internal pressure of the bubble, P ∞ is the hydrostatic pressure at the bubble location.

[0099] Furthermore, in the bubble characteristic parameter acquisition module at time zero, the compressible spherical bubble pulsation equation is used to perform time integration in reverse, and the initial time is the time of maximum bubble volume. The compressible bubble pulsation equation adopts the following equation:

[0100]

[0101] Where R is the bubble radius at any time, and are the first-order time derivative and the second-order time derivative of the bubble radius, C is the sound velocity of the flow field, H is the enthalpy difference on the bubble surface, is the first time derivative of the enthalpy difference.

[0102] Furthermore, in the bubble characteristic parameter acquisition module at time zero, the enthalpy difference on the bubble surface is calculated using the adiabatic equation:

[0103]

[0104] Among them, ρ is the density of the fluid in the flow field, and κ is the gas adiabatic coefficient.

[0105] Furthermore, in the bubble characteristic parameter acquisition module at time zero, the bubble parameters in formula (2) are used as the initial conditions, and the fourth-order Runge-Kutta method is used to perform reverse time advancement on formula (3) to calculate the bubble radius change process, and the bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at time zero are obtained, which are used as the new bubble pulsation initial conditions, respectively denoted as R n0 , and P n0 .

[0106] Furthermore, in the judgment module, the new bubble pulsation initial conditions are used to calculate the time evolution of the bubble radius, with the initial time being the zero time, to obtain a new bubble energy loss value, and the energy magnitudes of the first and second cycles of the bubble in the calculation are recorded as E nf and E ns .

[0107] Furthermore, in the judgment module, it is judged whether the energy loss value of the bubble has reached the target value. When the error between the calculated energy loss value of the bubble and the target value is within 3%, it is considered that the target has been reached, that is, the judgment is made according to the following formula:

[0108]

[0109] Furthermore, in the judgment module, if the calculation result satisfies formula (5), R n0 , and P n0 As the final initial condition of bubble pulsation, it is used to carry out theoretical or numerical analysis in engineering and basic scientific research without the need for subsequent steps.

[0110] Furthermore, in the calculation and storage module, if the calculation result in step 4 does not satisfy formula (5), it means that the internal pressure at the moment of maximum bubble volume deviates from the target working condition, and it is necessary to return to step 2 to adjust the bubble internal pressure value at the moment of maximum bubble volume, and then use formula (3) to calculate the bubble radius, pulsation velocity absolute value and bubble internal pressure at time zero again.

[0111] Furthermore, in the calculation and storage module, the adjustment of the bubble internal pressure value at the moment of maximum bubble volume needs to be considered according to the calculation result in step 4. Specifically, if the calculated energy loss value of the bubble is greater than the target value, the bubble internal pressure needs to be increased, otherwise the bubble internal pressure needs to be reduced. In the present invention, the adjustment range of the bubble internal pressure is set to 2% of the bubble internal pressure in the first reverse integral calculation.

[0112] Furthermore, in the calculation and storage module, the bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at the zero time in the recalculation are used as the initial conditions of the bubble pulsation, and the bubble radius change process is calculated using formula (3) to determine whether the energy loss value of the bubble reaches the target value. This cycle is repeated until formula (5) is satisfied.

[0113] Furthermore, in the calculation and storage module, the final equation (5) is recorded to obtain the bubble radius, pulsation velocity and bubble internal pressure at the time zero after the bubble pulsation, which is used as the initial condition of the bubble pulsation to serve the theoretical and numerical simulation in engineering applications and basic scientific research.

[0114] Implementation Method 3

[0115] An embodiment of the present invention provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected via a bus. Specifically, the processor implements any step in the first embodiment above by running the computer program stored in the memory.

[0116] It should be understood that in the embodiments of the present invention, the processor referred to may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0117] The memory may include a read-only memory, a flash memory, and a random access memory, and provides instructions and data to the processor. A part or all of the memory may also include a nonvolatile random access memory.

[0118] It can be seen from the above that the electronic device provided in the embodiment of the present invention can implement the bubble pulsation initial condition inversion method based on the bubble energy loss target as described in embodiment one by running a computer program, and proposes a method for determining the initial conditions of underwater pulsating bubbles suitable for any environmental conditions, thereby solving the problem that the theoretical and numerical calculation results in the existing bubble dynamics research cannot accurately reproduce the target results, achieving the purpose of accurately predicting the initial conditions of bubble pulsation under any conditions, and providing technical support for related basic scientific research on bubble dynamics.

[0119] It should be understood that if the above-mentioned integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned implementation method, and can also be completed by instructing the relevant hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method implementations when executed by the processor. Among them, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form. The above-mentioned computer-readable medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0120] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest range consistent with the principles and novel features disclosed herein.

[0121] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the implementation method can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method implementation method, which will not be repeated here.

[0122] It should be noted that the methods and detailed examples provided in the above embodiments can be combined with the devices and equipment provided in the embodiments, and references can be made to each other, and no further details will be given.

[0123] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0124] In the embodiments provided by the present invention, it should be understood that the disclosed device / terminal equipment and method can be implemented in other ways. For example, the device / equipment implementation described above is only illustrative, for example, the division of the above modules or units is only a logical function division, and in actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0125] The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above-mentioned embodiments, or replace some of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A bubble pulsation initial condition inversion method based on bubble energy loss target, characterized in that: The inversion method comprises the following steps: Step 1: input the characteristic parameters and energy parameters of the bubble and determine the target variable value of the inversion calculation; Step 2, taking the moment of maximum bubble volume as the initial calculation moment, arbitrarily giving a bubble internal pressure value at the moment of maximum bubble volume, and determining the initial condition of the bubble in the inversion calculation; Step 3, based on the compressible spherical bubble pulsation equation, reverse time integration is performed to obtain the bubble characteristic parameters at time zero; Step 4, using the bubble characteristic parameters obtained by reverse time integration as the initial conditions of bubble pulsation, calculating the time evolution process of the bubble radius, and judging whether the energy loss of the bubble has reached the target value; Step 5, adjust the bubble internal pressure value at the moment of maximum bubble volume in step 2 and recalculate, solve the bubble radius time history process, record the bubble characteristic parameters after reaching the expected target, and use them as new bubble pulsation initial conditions.

2. The method for inverting initial conditions of bubble pulsation according to claim 1, characterized in that: In the step 1, characteristic parameters and energy parameters of the bubble are input, including the time corresponding to the maximum volume of the bubble, the maximum radius of the bubble in the first period, and the maximum radius of the bubble in the second period, to determine the energy loss value of the bubble; In step 1, the energy ratio of the bubble in the first two pulsation cycles can be calculated as follows: Where E f and E s are the energy of the first and second cycles of the bubble, R maxf and R maxs are the maximum radii of the first and second cycles of the bubble, respectively.

3. The method for inverting initial conditions of bubble pulsation according to claim 2, characterized in that: In step 2, the maximum volume moment of the bubble in the first cycle is taken as the initial calculation moment. At this time, the pulsation speed of the bubble is zero. For any given bubble internal pressure value at the maximum volume moment, this patent takes it as one percent of the hydrostatic pressure at the location of the bubble. Therefore, the initial condition of the bubble in the inversion calculation can be determined as follows: Where R0 is the radius of the bubble at the initial calculation time, is the pulsation speed of the bubble at the initial calculation time, P0 is the initial internal pressure of the bubble, P ∞ is the hydrostatic pressure at the bubble location.

4. The method for inversion of initial conditions of bubble pulsation according to claim 1, characterized in that: In step 3, the compressible spherical bubble pulsation equation is used to perform time integration in reverse, and the initial time is the time when the bubble has the maximum volume. The compressible bubble pulsation equation adopts the following equation: Where R is the bubble radius at any time, and are the first-order time derivative and the second-order time derivative of the bubble radius, C is the sound velocity of the flow field, H is the enthalpy difference on the bubble surface, is the first time derivative of the enthalpy difference; In step 3, the enthalpy difference on the bubble surface is calculated using the adiabatic equation: Among them, ρ is the density of the fluid in the flow field, and κ is the gas adiabatic coefficient.

5. The method for inverting initial conditions of bubble pulsation according to claim 4, characterized in that: In step 3, the bubble parameters in formula (2) are used as initial conditions, and the fourth-order Runge-Kutta method is used to perform reverse time advancement on formula (3) to calculate the radius change process of the bubble, and the bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at time zero are obtained, which are used as new initial conditions for bubble pulsation, respectively denoted as R n0 , and P n0 .

6. The method for inverting initial conditions of bubble pulsation according to claim 1, characterized in that: In step 4, the time evolution process of the bubble radius is calculated using the new initial conditions of bubble pulsation, with the initial time being time zero, to obtain a new bubble energy loss value, and the energy magnitudes of the first and second cycles of the bubble in the calculation are respectively recorded as E nf and E ns ; Determine whether the energy loss value of the bubble has reached the target value. When the error between the calculated energy loss value of the bubble and the target value is within 3%, it is considered that the target has been reached, that is, it is determined according to the following formula: If the calculation result satisfies formula (5), R n0 , and P n0 As the final initial condition of bubble pulsation, it is used to carry out theoretical or numerical analysis in engineering and basic scientific research without the need for subsequent steps.

7. The method for inversion of initial conditions of bubble pulsation according to claim 1, characterized in that: In step 5, if the calculation result in step 4 does not satisfy formula (5), it means that the internal pressure at the moment of maximum bubble volume deviates from the target working condition, and it is necessary to return to step 2 to adjust the bubble internal pressure value at the moment of maximum bubble volume, and then use formula (3) to calculate the bubble radius, pulsation velocity absolute value and bubble internal pressure at time zero again; The adjustment of the bubble internal pressure value at the moment of maximum bubble volume needs to be considered based on the calculation results in step 4; The bubble radius, the absolute value of the pulsation velocity and the bubble internal pressure at the zero time in the recalculation are used as the initial conditions of the bubble pulsation. Formula (3) is used to calculate the change process of the bubble radius to determine whether the energy loss value of the bubble reaches the target value. This cycle is repeated until formula (5) is satisfied. The final equation (5) is recorded to obtain the bubble radius, pulsation velocity and bubble internal pressure that satisfy the post-zero time, which is used as the initial condition of bubble pulsation to serve the theoretical and numerical simulation in engineering applications and basic scientific research.

8. A bubble pulsation initial condition inversion system based on bubble energy loss target, characterized in that: The inversion system uses the bubble pulsation initial condition inversion method based on the bubble energy loss target as claimed in any one of claims 1 to 7, and the inversion system includes: The target variable value determination module inputs the characteristic parameters and energy parameters of the bubble to determine the target variable value of the inversion calculation; The bubble initial condition determination module takes the moment of maximum bubble volume as the initial calculation moment, and arbitrarily gives a bubble internal pressure value at the moment of maximum bubble volume to determine the bubble initial condition in the inversion calculation; The bubble characteristic parameter acquisition module at time zero performs reverse time integration based on the compressible spherical bubble pulsation equation to obtain the bubble characteristic parameters at time zero; A judgment module uses the bubble characteristic parameters obtained by reverse time integration as the initial conditions of bubble pulsation, calculates the time evolution process of the bubble radius, and judges whether the energy loss of the bubble has reached the target value; The calculation and storage module adjusts the bubble initial condition determination module to recalculate the bubble internal pressure value at the moment of the bubble's maximum volume, solves the bubble radius time history process, and records the bubble characteristic parameters after reaching the expected target, which are used as new bubble pulsation initial conditions.

9. A computer device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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