A method and system for simulating multi-form compound tsunami surges using a dual dam-break model

Abstract

The application discloses a method and system for simulating multi-form composite tsunami surge waves by means of a double-dam model, and belongs to the technical field of tsunami surge wave researches. The method comprises the following steps: constructing a double-dam physical model; precisely controlling input Froude numbers by adjusting the initial water depth ratio on both sides of a gate, so as to simulate flow states of surge waves with different intensities; collecting the free surface elevation time history, instantaneous flow velocity and climbing height of the surge waves by means of a data acquisition unit; establishing a two-dimensional numerical flume model corresponding to the physical model based on an incompressible smoothed particle hydrodynamics (ISPH) method; and performing numerical simulation and verification. The application realizes controllable physical simulation of complex tsunami waveforms, provides clear waveform generation conditions, enhances the reliability of numerical results, and provides a means for revealing flow field details that are difficult to observe in physical experiments.

Description

Technical Field

[0001] This invention belongs to the field of tsunami surge research technology, and in particular relates to a method and system for simulating multi-form composite tsunami surges using a double dam-break model. Background Technology

[0002] Tsunami surges have become a research hotspot in coastal engineering and disaster prevention due to their intense destructive power. When multiple tsunami waves arrive consecutively and superimpose, their combined effect often amplifies the disaster's impact. Therefore, realistically reproducing combined tsunami surges in the laboratory and quantitatively assessing their effects on coastal structures has significant scientific and engineering value.

[0003] Currently, the dam-break method is one of the most commonly used methods for generating tsunami surges in laboratories. Its principle is based on the theory of unsteady flow in hydraulics, simulating surges by rapidly opening gates to release reservoir water. However, traditional single-dam-break methods can only generate a single surge, failing to simulate the complex waveforms of multiple waves superimposed or "receding then rising" in actual tsunamis. To address this issue, Chinese patent CN 121496878 A proposes a rapid dam-break device for generating complex tsunamis. This device achieves surge coupling by sequentially opening two gates, providing a hardware foundation for the physical simulation of complex tsunamis. However, this application primarily focuses on the mechanical structure design of the dam-break device and the rapid lifting of the gates, without revealing the controllable generation conditions for the waveform type or establishing a quantitative control model between surge intensity and water depth ratio.

[0004] In terms of numerical simulation, Chinese patent CN119249953B proposes a method for simulating sediment erosion around structures under conventional wave action using an ISPH combined with a modified k-ε turbulence model. However, this application mainly focuses on the numerical simulation of sediment erosion under conventional wave conditions, and does not involve the numerical simulation of the generation, propagation, and ramp-up process of composite tsunami surges, nor does it establish the correspondence between the intensity and waveform morphology of composite surges. Summary of the Invention

[0005] To address the aforementioned shortcomings, this invention proposes a method and system for simulating multi-form composite tsunami surges using a double-dam-break model. The aim is to comprehensively solve the problems of "controllable generation—dynamic verification—quantitative evaluation" of composite tsunami surges by establishing a clear correspondence between water depth ratio and waveform type, deriving a quantitative correlation between input Froude number and surge intensity, and introducing an improved ISPH numerical model and momentum flux assessment method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] On the one hand, there is a method for simulating multi-form composite tsunami surge waves using a double-dam-break model. The method steps are as follows:

[0008] S1, Constructing a physical model of a double-dam failure: A sandy bank is set at one end of the experimental flume, and a first and second gate are set at the other end. The water source is divided into a downstream still water zone, a first reservoir, and a second reservoir, with the downstream still water zone having a water depth of [missing information]. The first reservoir has a water depth of The second reservoir has a water depth of And satisfying, or ;

[0009] S2, generating a composite tsunami surge: the input Froude number is precisely controlled by adjusting the initial water depth ratio on both sides of the gate. This allows for the simulation of surge flow patterns of different intensities.

[0010] First, the first gate is opened to release water from the first reservoir, generating the first tsunami surge. After a predetermined interval, the second gate is opened to release water from the second reservoir, generating the second tsunami surge. The two surges superimpose during propagation to form a composite continuous surge or an N-type surge.

[0011] S3, Collect experimental data: Use the data acquisition unit to collect the free surface elevation time history, instantaneous velocity and rise height of the surge wave;

[0012] S4. Establishing a numerical model for a double-dam failure: Based on the incompressible smooth particle hydrodynamics ISPH method, a two-dimensional numerical flume model corresponding to the physical model is established, using a modified... Solving the Reynolds-averaged Navier-Stokes equations using a closed-loop turbulence model by introducing a stress constraint factor And gradient-corrected dynamically stable schemes suppress non-physical turbulence and reduce numerical dissipation;

[0013] S5, Numerical Simulation and Verification: The ISPH numerical model is used to simulate the generation, propagation, ramp-up, and receding process of the composite tsunami surge. The numerical simulation results are compared and verified with physical experimental data, including: comparing the time history of free surface elevation, the time history of flow velocity, and the measured value and empirical formula prediction value of surge rise height between the numerical simulation and the physical experiment.

[0014] Furthermore, in step S2, the formation of a composite continuous surge wave or an N-type surge wave is achieved by controlling the gate opening conditions, and the Froude number is used to analyze the transient free surface flow:

[0015] Determine the difference in water level on both sides of the gate to define the surge wave intensity. The calculation formula is:

[0016]

[0017] When F > 1, a positively advancing surge wave is formed;

[0018] In the formula, The surge wave front velocity is taken as the velocity of the dam-break water front or the cross-sectional average velocity. For long-wave velocity in still water, It is the acceleration due to gravity;

[0019] The relationship between surge wave intensity and the water depth and flow velocity behind the surge wave is as follows:

[0020]

[0021]

[0022] In the formula, The velocity following the surge wave. The water depth in the area behind the surge wave. The still water depth in the tank. This refers to the surge wave velocity.

[0023] Furthermore, according to the theory of characteristics, the positive characteristic lines emanating from the still water zone of the reservoir satisfy the conservation of Riemann invariants. At this point, the functional relationship between the water depth ratio on both sides of the gate and the surge wave intensity is:

[0024]

[0025] Furthermore, in step S2: the generation conditions for the composite continuous surge wave are: The first and second surge waves arrive at the sloping shoreline successively and superimpose; the generation conditions of the N-type surge wave are: When the first gate is opened, the water in the still water area first falls back into the first reservoir, and then the second gate is opened, forming a wave pattern in which the water level first drops and then rises.

[0026] Furthermore, the composite surge wave includes at least two combinations of surge waves with different intensities.

[0027] Furthermore, the method also includes: calculating the momentum flux of the surge wave at the toe of the slope based on the discrete expression of momentum flux from the ISPH numerical model.

[0028]

[0029] in For particle mass The velocity component of the particle along the slope direction is used to quantitatively assess the dynamic intensity of the composite surge wave.

[0030] Furthermore, under near-shore unattenuated surge conditions, the maximum surge height is related to the initial input surge intensity. To maintain a stable positive correlation, the relationship can be expressed as follows:

[0031]

[0032] On the other hand, there is a system for simulating multi-form composite tsunami waves using a double-dam-break model, including:

[0033] A dual-dam-break physical model unit for generating multi-form composite tsunami surges, the dual-dam-break physical model unit comprising:

[0034] The physics experimental water tank has a sloping bank at its downstream end.

[0035] The first gate is located in the experimental water tank, upstream of the sloping bank, and is used to divide the experimental water tank into a downstream still water area and an upstream reservoir area.

[0036] The second gate is located in the upstream reservoir area and is used to further divide the upstream reservoir area into the first reservoir and the second reservoir.

[0037] The first gate and the second gate are respectively connected to a gate control device, which is used to control the opening sequence, opening speed and opening height of the two gates;

[0038] The data acquisition unit is set up on the experimental water tank and the sloping bank to collect the wave height, flow velocity and pressure parameters of the surge wave;

[0039] The ISPH numerical simulation unit is used to establish a two-dimensional numerical flume model corresponding to the double-dam-break physical model unit, and to perform numerical simulation of the generation and propagation process of the composite tsunami surge based on the incompressible smooth particle hydrodynamics ISPH method.

[0040] Furthermore, the physical experiment tank has a total length of 33.4m, a width of 1.5m, and a height of 2m. A sand slope is constructed at the downstream end of the tank, with a 5-meter-long bank and a slope of 1:25, using sand with a particle size of... It is made of 0.18mm sand, and the first gate is located 8.4 meters upstream of the sloping bank.

[0041] Furthermore, the total length of the two-dimensional numerical flume model is 33.6m, and the height is 1.1m. The sloping bank is located at the downstream end of the flume with a slope of 1:25. The diameters of the numerical particles are set to 0.01 and 0.005, respectively, and the time step range is controlled within... arrive The simulation was run using 20 cores and 40 cores respectively. Multiple numerical wave height measurement points were set up at the toe of the slope and on the sloping bank at distances of 6m, 10.3m, and 13.3m from the toe of the slope. Numerical velocity measurement points were also set up at the toe of the slope to collect velocity data at the corresponding locations during the simulation.

[0042] The beneficial effects of this invention are:

[0043] 1. Achieving Controllable Physical Simulation of Complex Tsunami Waveforms: This invention, by setting up dual gates and three different water depth zones, and controlling the sequential opening and closing of the gates, can generate composite continuous surge waves and N-type surge waves. Compared with the traditional single dam-break method, it can more realistically simulate the complex process of multiple wave superposition or receding followed by rising in actual tsunamis.

[0044] 2. Provide explicit waveform generation conditions: based on water depth ( or It can stably obtain composite continuous surge waves or N-type surge waves, making the experimental scheme highly controllable and repeatable.

[0045] 3. Improved accuracy and stability of numerical simulation: Based on the improved ISPH method, a modified... The turbulence model, stress constraint coefficient λ3, and gradient-corrected dynamic stabilization scheme effectively suppress non-physical turbulence and numerical dissipation, significantly improving the simulation accuracy of tsunami surge generation, propagation, and ramp-up processes.

[0046] 4. Two-way verification between physical experiments and numerical simulations: By comprehensively utilizing high-precision experimental data (free surface elevation, flow velocity, and climb height) and comparing them with the ISPH numerical model, the reliability of the numerical results is enhanced, and a means is provided to reveal flow field details that are difficult to observe in physical experiments. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the experimental water tank sand slope and gate structure of the present invention;

[0048] Figure 2 This invention provides the free surface elevation of different morphologies of surge waves under a single surge wave condition.

[0049] Figure 3 This refers to the dimensionless free surface elevation of each measuring point in groups C1-C4 of this invention;

[0050] Figure 4 This is the instantaneous flow velocity time history of groups C1–C4 of the present invention at x=0;

[0051] Figure 5 This is a comparison of the waveforms from the physical experiment and the digital simulation experiment of this invention;

[0052] Figure 6 The flow velocity diagrams for groups C1, C2, and C3 of this invention;

[0053] Figure 7 Turbulent kinetic energy diagrams for groups C1, C2, and C3;

[0054] Figure 8 This is a comparison diagram of the rise of the composite continuous surge wave and the N-type surge wave of the present invention;

[0055] Figure 9 This is a diagram showing the slope toe intensity variation of the N-type surge wave of this invention;

[0056] Figure 10 This is a diagram showing the change in slope toe strength for single and combined surge waves according to the present invention. Detailed Implementation

[0057] A method for simulating multi-form composite tsunami surge waves using a double dam-break model, the steps of which are as follows:

[0058] S1, Constructing a physical model of a double-dam failure

[0059] A sandy bank was constructed at one end of the experimental water tank, and a first and second sluice gate were installed at the other end. The water source was divided sequentially into a downstream still water zone, a first reservoir, and a second reservoir. The water depth in the downstream still water zone was [missing information]. The first reservoir has a water depth of The second reservoir has a water depth of The intensity of the surge wave can be controlled by adjusting the water level difference on both sides of the gate.

[0060] S2, generating a complex tsunami surge.

[0061] The input Froude number is precisely controlled by adjusting the initial water depth ratio on both sides of the gate. This simulates surge flow patterns of different intensities: First, the first gate is opened to release water from the first reservoir, generating the first tsunami surge. After a predetermined interval, the second gate is opened to release water from the second reservoir, generating the second tsunami surge. The two surges superimpose during propagation, forming a composite continuous surge with a wave train-like continuous advancing waveform, or an N-shaped surge with the water surface first falling and then rising, exhibiting an N-shaped profile.

[0062] In physics experiments, a surge wave is generated by instantaneously raising a sluice gate to release water. This causes the fluid to accelerate under gravity, forming a surge wave characteristic of a tsunami. Based on nonlinear shallow water wave theory and the method of characteristics, surge wave intensity is defined as the surge wave front velocity. Longwave velocity in still water The ratio of to . Surge intensity The calculation formula is:

[0063]

[0064] According to the laws of conservation of mass and momentum near the wavefront, the relationship between surge wave intensity and the water depth and flow velocity behind the surge wave is as follows:

[0065]

[0066]

[0067] In the formula, The velocity following the surge wave. The water depth in the area behind the surge wave. The still water depth in the tank. This refers to the surge wave velocity.

[0068] When F > 1, a positively advancing surge wave is formed;

[0069] According to the theory of characteristics, the positive characteristic lines emanating from the still water zone of the reservoir satisfy the conservation of Riemann invariants. At this point, the functional relationship between the water depth ratio on both sides of the gate and the surge wave intensity is:

[0070]

[0071] D utilizes the aforementioned dam-break system to generate surge waves and precisely controls the input Froude number by adjusting the initial water depth ratio on both sides of the gate, thereby simulating surge wave flow patterns of different intensities. The generated surge waves can be classified into three typical forms:

[0072] (1) At that time, the morphology of the surge wave is an undulating surge wave;

[0073] (2) At this time, the surge wave presents as a transitional undulating-breaking surge wave;

[0074] (3) At that time, the tsunami wave is a breaking wave.

[0075] S3, Data Acquisition: The data acquisition unit collects the free surface elevation time history, instantaneous velocity, and rise height of the surge wave. The data acquisition unit includes multiple wave height meters, ultrasonic water level sensors, flow profilers, and a video recording system.

[0076] This embodiment considers two different shoreline slope conditions: [Slope conditions are described in the original text]. Under the given conditions, a total of 5 single-dam-break experiments were set up, numbered S1–S5; at the slope... Under these conditions, a total of 7 experimental groups were set up, numbered S6–S12. Four groups were double-dam failure experiments. Specific hydraulic parameters and corresponding wave condition types for each experimental group are detailed in Tables 1 and 2.

[0077] Experiment setup as follows Figure 1As shown in the figure, the black text indicates the instrument layout under the 40m flume condition, and the gray text indicates the instrument layout under the 33.6m flume condition. A total of 5 capacitive wave height meters (CGs) and 4 ultrasonic water level sensors (USs) were deployed in the experiment. The CGs were mainly installed in the fixed-depth area of ​​the flume, with a sampling frequency of 100Hz. The four USs with a sampling frequency of 50Hz were installed in the sand slope area: one at the toe of the slope, and the other three were respectively arranged on the wave-facing side, side, and back of the cylinder, used to measure local water level changes near the structure. Current velocity was measured using the Vectrino II acoustic Doppler current profiler (ADV) manufactured by Nortek AS of Norway. The specific installation coordinates of the wave height meters and current velocity measurement points are summarized in Table 3. To record the entire process of surge wave propagation and its interaction with the shoreline structure, multiple video recording systems were deployed in the experiment. A high-speed camera (sampling rate 10 frames / second) was deployed on the outer side of the flume to record the overall process of the surge wave impacting the beach. A full HD camera was installed on the top of the sand slope to record the wave's ascent and recede from above. Simultaneously, HD cameras were deployed inside and outside the cylindrical structure to observe the local scour development process around the cylinder. After the experiment, a high-precision scan of the sand bed topography around the cylinder was performed using a SCANTECH iReal 2E handheld 3D scanner. Based on the scan data, the sand bed morphology was reconstructed, allowing for quantitative analysis of the final scour depth and scour morphology characteristics.

[0078] Table 1. Experimental Groups of Single-Fail Dams

[0079]

[0080] In the table, The particle size of the sand on the slope.

[0081] Table 2 Experimental Groups of Double-Failure Dams

[0082]

[0083] Table 3 Sensor location coordinates

[0084]

[0085] In Table 2, group C4 represents the N-type surge condition. , Not applicable, indicated by "—".

[0086] Experimental results show that after the gates of the dam-break system are opened instantaneously, the water in the reservoir collapses rapidly and gradually evolves into a forward-propagating surge. When the surge front reaches the toe of the sand slope, the flow structure changes significantly, triggering the surge to rise on the beach and subsequently receding.

[0087] Figure 2 This is a free surface elevation map of different morphologies of surge waves under a single surge wave condition. The initial still water depth h0 is used to make the surface disturbance η dimensionless to obtain η / h0, which is used to represent the rise of the wave relative to the water depth, thus avoiding scale interference caused by the difference in water depth under different working conditions. Figure 2 (a) Dimensionless free surface elevation time history of group S1-5 at CG2 Figure 2 (b) Time histories of dimensionless free surface elevation at CG2 for groups S6, S7, and S9. The starting point of the time is the time when the first wave arrives at the measuring point. Figure 2 (a) shows the effect of input The increase in surge volume indicates a transition in surge morphology from undulating surge to undulating-breaking surge. By comparing different operating conditions, it can be observed that when... At that time, the degree of fluctuation after the peak reaches its maximum; while when When the value increases further to 1.4, the surge front begins to break up locally, and the undulations decrease. Figure 2 (b) The slope of the sand dune was plotted. The time history of the free surface elevation at CG2 is shown in the figure. The figures represent the undulating surge waves. undulating-breaking surge waves and completely broken surge waves Three typical operating conditions.

[0088] Real-world tsunamis often exhibit complex waveforms such as multiple wave crests and continuous wave trains. To more closely approximate real-world conditions, this experiment employs a double-dam-break system. By controlling the sequential opening of two gates and setting different reservoir water levels, a composite surge wave is generated. In the composite continuous surge wave experiment, the first wave is designed as an undulating surge wave. undulations – broken surges and broken surge The second wave is fixed as .

[0089] Figure 3 For the evolution of free surface elevation, the black dashed line represents the free surface of a single surge wave, and the blue solid line represents the composite surge wave. Two typical composite surge waves were observed in the experiment: (1) Composite continuous surge wave: In groups C1-C3, by setting a stepped initial water depth First, the first gate was opened instantaneously to generate a single tsunami surge wave, thus generating a single surge wave; then, the second gate was opened, and two waves were observed arriving on the slope. That is, the two surge waves arrived one after the other and superimposed to form a wave train-like continuous advancing waveform. (2) N-type surge wave: In group C4, the experiment set the initial condition of negative drop. When the first gate is opened, the still water zone The water level in the area first dropped to In the affected area, the second dam was then opened, creating a typical N-shaped wave pattern of "water level first dropping and then rising." Through a double-dam-break system, composite surge waves that more closely resemble real nearshore tsunamis can be generated. The double-dam-break system can generate multi-form composite surge waves that more closely resemble real nearshore tsunamis.

[0090] Figure 4 The instantaneous velocity time history of groups C1–C4 at x=0 is shown, illustrating the velocity time history at the toe of the slope. Compared to single surge waves, composite surge waves not only induce higher peak transient velocities but also prolong the duration of high-velocity hydrodynamic action.

[0091] S4. Establishing a numerical model for a double-dam failure: Based on the incompressible smooth particle hydrodynamics ISPH method, a two-dimensional numerical flume model corresponding to the physical model is established, using a modified... Solving the Reynolds-averaged Navier-Stokes equations using a closed-loop turbulence model by introducing a stress constraint factor The gradient-corrected dynamic stabilization scheme suppresses non-physical turbulence and reduces numerical dissipation.

[0092] A two-dimensional numerical flume was constructed to simulate the hydrodynamic process. The numerical simulation experiment was simplified by omitting the cylindrical scouring. The experiment employed the Incompressible Smooth Particle Hydrodynamics (ISPH) method, which utilizes the Wang... Proposed amendments A turbulent closed-loop model is used to solve the two-dimensional Reynolds-averaged Navier-Stokes (RANS) equations.

[0093] The mass conservation equation and momentum conservation equation of the ISPH governing equation are established, and the Navier-Stokes equation is expressed as follows:

[0094]

[0095]

[0096] In the formula, For fluid density, For time, For ensemble average velocity, It is the acceleration due to gravity. The coefficient of kinematic viscosity, For pressure, Let be the Reynolds stress tensor.

[0097] Standard The turbulence model is modified, and the turbulent eddy viscosity in the Reynolds stress tensor expression is calculated. In each particle Turbulent kinetic energy is defined everywhere. and energy dissipation rate In response to turbulence in the ocean, the standard Closed models have the following forms:

[0098]

[0099]

[0100] In the formula, , , , , The term representing the generation of turbulent kinetic energy. For time, the viscosity of the turbulent eddy current Make corrections:

[0101]

[0102] In the formula, To correct the dissipation rate, take , ,

[0103] ,in Represents the deformation rate tensor. The rotational rate tensor represents the ensemble-averaged flow field. The subscript 'initial' indicates the time-averaged and depth-averaged values ​​within the first wave cycle in the potential flow region. , , , and These are empirical constants, in this model , , .

[0104] In the numerical model, the wave generation method is consistent with the physical experiment, and the slope is... The total length of the numerical water tank is 40.0m and the height is 1.0m; The numerical water tank has a total length of 33.6 m and a height of 1.0 m. The diameter of the numerical particles is set to 0.005 m, and the time step range is controlled within... arrive It runs on 20 cores, and each experiment lasts for 5 days.

[0105] In addition to the numerical model comparison with the physical experiments, 65 additional numerical model experiments were added as supplementary experiments, of which Tables 3 and 5 show some of the experimental groups. In the double-dam failure experiment, the fixed , It is 0.1. , .

[0106] Table 4 Single Dam Failure Test Conditions

[0107]

[0108] Table 5 Experimental conditions for double-dam failure

[0109]

[0110] S5, Numerical Simulation and Verification: The ISPH numerical model is used to simulate the generation, propagation, ramp-up, and receding process of the composite tsunami surge. The numerical simulation results are compared and verified with physical experimental data, including: comparing the time history of free surface elevation, the time history of flow velocity, and the measured value and empirical formula prediction value of surge rise height between the numerical simulation and the physical experiment.

[0111] Figure 5 This is a comparison of waveforms from physical experiments and numerical simulation experiments. The red dots represent the physical experiments, showing a comparison of waveforms in groups S2 and S5 during the slope ascent process. The results show that the numerical simulation can accurately reproduce the free surface morphology of the surge wave during its propagation and ascent on the slope, and the simulated wavefront profile matches the physical experiment results well. This indicates that the established numerical model can effectively capture the main hydrodynamic characteristics of the surge wave during the ascent process, and has high computational accuracy and reliability.

[0112] In addition, three typical single surge wave conditions (S7, S8, and S9) were selected for further model verification. In the verification calculations, the experimental setup of the numerical flume was consistent with the physical experiments. The results show that the numerical calculation results are highly consistent with the experimental data in terms of overall trends and phase evolution, verifying that the numerical method can effectively reproduce the hydrodynamic characteristics of surge waves. Overall, the numerical simulation results agree well with the physical experimental data, indicating that the ISPH method can effectively capture the main characteristics of the flow field under different flow velocity conditions and has good computational accuracy.

[0113] Figure 6 and Figure 7The velocity field and turbulent kinetic energy distribution characteristics of single and composite surge waves in the nearshore region were further compared. The results show significant differences between the two. Composite surge waves generated by the double-dam-break system exhibit more intense wavefront undulations and more complex turbulent structures. Under single-dam-break conditions, the high-velocity region is mainly concentrated in the instantaneous impact phase of the surge wave front; while under composite surge wave conditions, the superposition of continuous surge waves maintains a high-velocity state in the shore area for a longer period. Regarding turbulent kinetic energy distribution, composite surge waves are not simply linear superpositions. The second surge wave propagates in the turbulent environment formed by the first surge wave. This process significantly enhances the instability of the flow field, not only greatly increasing the local turbulent kinetic energy peak value but also extending the highly turbulent region from the surface to the deep water region. In summary, due to the nonlinear interaction between waves, the local peak velocity and turbulent kinetic energy intensity generated by composite surge waves are significantly higher than those under single-dam-break conditions.

[0114] This invention estimates the surge propagation velocity by utilizing the time difference and distance between the surge wave fronts arriving at two measuring points, thereby determining the surge intensity at the toe of the slope. .

[0115] The propagation speed of a surge wave can be expressed as:

[0116]

[0117] in, and It is the location of the measuring point. and This represents the arrival time of the surge wave front recorded at the corresponding measurement point.

[0118] This method allows us to obtain the Froude number of the surge wave at the foot of the slope, and the Froude number at the foot of the slope is defined as the surge wave intensity at the foot of the slope. Furthermore, maximum rise height is an important indicator for assessing the potential for tsunami damage to coastal infrastructure. This invention employs an empirical prediction formula to establish a relationship between the intensity of the surge wave at the toe of the slope and the maximum rise height:

[0119]

[0120] This formula can be used to predict the maximum climb height under different slope and surge wave intensities. The results show that the experimental measurements and the predicted results are in good agreement, further verifying the accuracy and reliability of the method, and also indicating the strength of the surge wave at the toe of the slope. It has a significant control effect on the maximum climbing height.

[0121] In the double-dam failure experiment, based on the water depth of the second reservoir... Compared with downstream still water depth Define the dimensionless input intensity parameters of the composite surge wave. The surge intensity of the first wave at the toe of the slope in the composite surge is basically the same as that in the single surge condition, indicating that before the second gate opens, the propagation of the first surge is controlled only by the water level difference on both sides of the first gate and the downstream still water conditions, and has not yet been affected by subsequent waves. The intensity of the second surge at the toe of the slope... They exhibit different characteristics. It depends not only on the input strength Also related to the water depth in the middle Related. When When smaller, The value basically remained at the input intensity Nearby, it exhibits linear characteristics; when When it is large, The nonlinear growth trend is because the second surge wave does not propagate in still water, but advances in the onshore background flow field formed by the first surge wave, resulting in wave velocity superposition and a significant increase in the instantaneous Froude number measured at the toe of the slope.

[0122] From the perspective of momentum conservation, the intensity of the surge wave's effect on the bank slope at the toe can be represented by momentum flux. In the ISPH numerical model, this equation can be discretized into a particle summation form:

[0123]

[0124] in For particle mass The velocity component of the particle along the slope direction is used to quantitatively assess the dynamic intensity of the composite surge wave. This quantity reflects the momentum intensity transported by the surge wave to the slope per unit time, thus effectively characterizing the dynamic features of the incident surge wave at the slope toe. During the propagation of the composite surge wave, the first surge wave, upon reaching the slope toe, creates a certain background flow within the channel, providing the initial velocity for the subsequent second surge wave. When the second surge wave propagates to the vicinity of the slope toe, its velocity field no longer develops from a still water state but is formed by superposition on the existing background flow velocity. The velocity vector superposition of the two surge waves within the slope toe control area significantly increases the local flow velocity, thus affecting the slope toe surge wave intensity. Greater than a single surge.

[0125] The maximum climb height of the composite surge group TC1-TC30 is as follows: Figure 8 As shown, where Figure 8 (a) The rise height of a composite continuous surge wave and a single surge wave were compared. When the incident intensity... When the intensity is relatively low (less than 1.9), the rise and toe surge intensity of the composite continuous surge wave show good consistency with those of the single surge wave, basically conforming to existing empirical prediction formulas. This indicates that under low intensity conditions, the energy of the surge wave is relatively stable during propagation, and the dynamic parameters at the toe can well reflect its final rise capability. However, when... When the flow is large, the first surge establishes a background velocity towards the shore during propagation, effectively reducing the frictional resistance of the second surge. This combined interaction mechanism prolongs the duration of high velocity, allowing the combined surge to maintain a high energy flux at the same location where the single surge has significantly attenuated due to long-distance propagation, thus generating a higher rise height than the single surge. For N-type surges, the variation law of slope toe intensity is as follows: Figure 9 As shown. When fixed At that time, at the foot of the slope The surge intensity decreases with increasing input intensity. This phenomenon is consistent with the previous analysis, which states that under higher intensity conditions, the surge wave is more likely to break up, thereby enhancing turbulent dissipation and reducing its propagation intensity.

[0126] Figure 8-10 It is evident that the hydrodynamic characteristics of composite surge waves differ significantly from those of single surge waves. Composite continuous surge waves Significantly higher than single surge waves; while N-type surge waves Lower than a single surge. However, although the intensity of different types of surges varies significantly at the toe of the slope, their corresponding maximum rise heights do not strictly follow the pattern of single surges. This phenomenon indicates that, under combined surge wave conditions, the surge wave intensity at the toe of the slope varies according to traditional empirical formulas for controlling variables. This is not sufficient to completely determine the final rise height. Furthermore, this invention primarily focuses on the analysis of near-shore unattenuated surge conditions. Under these conditions, the energy attenuation of the surge during propagation is relatively limited; therefore, the maximum rise height is always related to the initial input surge intensity. A stable positive correlation is maintained. This indicates that in such cases, the climb process is primarily controlled by the initial hydrodynamic characteristics of the incident surge wave, while the instantaneous local intensity at the toe of the slope has a relatively limited impact on the final climb height. These results suggest that under nearshore unattenuated composite surge wave conditions, the climb height is actually more directly controlled by the effective intensity of the incident surge wave. Therefore, in this type of problem, the original formula... It can be used This allows for a more accurate prediction of the maximum rise height of composite surges and improves the ability to predict the maximum rise height of composite surges.

[0127] One embodiment of the present invention is a system for simulating multi-form composite tsunami surges in a double-dam-break scenario, used in the above-described method. The system includes:

[0128] A double-dam-break physical model unit is used to generate multi-form composite tsunami surges. The double-dam-break physical model unit includes: a physical experimental flume with a sloping bank at its downstream end; a first gate located in the experimental flume, upstream of the sloping bank, used to divide the experimental flume into a downstream still water zone and an upstream reservoir zone; a second gate located in the upstream reservoir zone, used to further divide the upstream reservoir zone into a first reservoir and a second reservoir; the first gate and the second gate are respectively connected to gate control devices for controlling the opening sequence, opening speed, and opening height of the two gates.

[0129] The data acquisition unit is set up on the experimental water tank and the sloping bank to collect the wave height, flow velocity and pressure parameters of the surge wave.

[0130] The ISPH numerical simulation unit is used to establish a two-dimensional numerical flume model corresponding to the double-dam-break physical model unit, and to perform numerical simulation of the generation and propagation process of the composite tsunami surge based on the incompressible smooth particle hydrodynamics ISPH method.

[0131] The physical experiment tank has a total length of 33.4m, a width of 1.5m, and a height of 2m. A sand slope is constructed at the downstream end of the tank, with a 5-meter-long bank and a slope of 1:25. The sand used is of particle size D. 50 It is made of 0.18mm sand, and the first gate is located 8.4 meters upstream of the sloping bank.

[0132] The two-dimensional numerical flume model has a total length of 33.6m and a height of 1.1m. The sloping bank is located at the downstream end of the flume with a slope of 1:25. The diameters of the numerical particles are set to 0.01 and 0.005, respectively, and the time step range is controlled within... arrive The simulation was run using 20 cores and 40 cores respectively. Multiple numerical wave height measurement points were set up at the toe of the slope and on the sloping bank at distances of 6m, 10.3m, and 13.3m from the toe of the slope. Numerical velocity measurement points were also set up at the toe of the slope to collect velocity data at the corresponding locations during the simulation.

[0133] Finally, it should be noted that the embodiments described in this invention are merely preferred embodiments to illustrate the invention, and not limitations on the implementation of the invention. Therefore, it is neither necessary nor possible to list all possible implementations. Thus, those skilled in the art can make any modifications or variations to the embodiments described in this invention. Any modifications, improvements, or equivalent substitutions made within the spirit and principles of this invention are included within the scope of protection claimed by this invention.

Claims

1. A method for simulating multi-form composite tsunami surge waves using a double-dam-break model, characterized in that, The steps are as follows: S1, Constructing a physical model of a double-dam failure: A sandy bank is set at one end of the experimental flume, and a first and second gate are set at the other end. The water source is divided into a downstream still water zone, a first reservoir, and a second reservoir, with the downstream still water zone having a water depth of [missing information]. The first reservoir has a water depth of The second reservoir has a water depth of And satisfying, or ; S2, generating a composite tsunami surge: the input Froude number is precisely controlled by adjusting the initial water depth ratio on both sides of the gate. This allows for the simulation of surge flow patterns of different intensities. First, the first gate is opened to release water from the first reservoir, generating the first tsunami surge. After a predetermined interval, the second gate is opened to release water from the second reservoir, generating the second tsunami surge. The two surges superimpose during propagation to form a composite continuous surge or an N-type surge. S3, Collect experimental data: Use the data acquisition unit to collect the free surface elevation time history, instantaneous velocity and rise height of the surge wave; S4. Establishing a numerical model for a double-dam failure: Based on the incompressible smooth particle hydrodynamics ISPH method, a two-dimensional numerical flume model corresponding to the physical model is established, using a modified... Solving the Reynolds-averaged Navier-Stokes equations using a closed-loop turbulence model by introducing a stress constraint factor And gradient-corrected dynamically stable schemes suppress non-physical turbulence and reduce numerical dissipation; S5, Numerical Simulation and Verification: The ISPH numerical model is used to simulate the generation, propagation, ramp-up, and receding process of the composite tsunami surge. The numerical simulation results are compared and verified with physical experimental data, including: comparing the time history of free surface elevation, the time history of flow velocity, and the measured value and empirical formula prediction value of surge rise height between the numerical simulation and the physical experiment.

2. The method for simulating multi-form composite tsunami surge waves using a double-dam-break model according to claim 1, characterized in that, In step S2, the formation of a composite continuous surge wave or an N-type surge wave is achieved by controlling the gate opening conditions. The Froude number is used to analyze the transient free surface flow. Determine the difference in water level on both sides of the gate to define the surge wave intensity. The calculation formula is: When F > 1, a positively advancing surge wave is formed; In the formula, The surge wave front velocity is taken as the velocity of the dam-break water front or the cross-sectional average velocity. For long-wave velocity in still water, It is the acceleration due to gravity; The relationship between surge wave intensity and the water depth and flow velocity behind the surge wave is as follows: In the formula, The velocity following the surge wave. The water depth in the area behind the surge wave. The still water depth in the tank. This refers to the surge wave velocity.

3. The method for simulating multi-form composite tsunami surge waves using the double-dam-break model according to claim 2, characterized in that, According to the theory of characteristics, the positive characteristic lines emanating from the still water zone of the reservoir satisfy the conservation of Riemann invariants. At this point, the functional relationship between the water depth ratio on both sides of the gate and the surge wave intensity is:

4. The method for simulating multi-form composite tsunami surge waves using a double-dam-break model according to claim 1, characterized in that, In step S2: the generation conditions of the composite continuous surge wave are: The first and second surge waves arrive at the sloping shoreline successively and superimpose; the generation conditions of the N-type surge wave are: When the first gate is opened, the water in the still water area first falls back into the first reservoir, and then the second gate is opened, forming a wave pattern in which the water level first drops and then rises.

5. The method for simulating multi-form composite tsunami surge waves using the double-dam-break model according to claim 3, characterized in that, The composite surge wave includes at least two combinations of surge waves with different intensities.

6. The method for simulating multi-form composite tsunami surge waves using a double-dam-break model according to claim 1, characterized in that, The method further includes: calculating the momentum flux of the surge wave at the toe of the slope based on the discrete expression of momentum flux from the ISPH numerical model. in For particle mass The velocity component of the particle along the slope direction is used to quantitatively assess the dynamic intensity of the composite surge wave.

7. The method for simulating multi-form composite tsunami surge waves using a double-dam-break model according to claim 1, characterized in that, Under near-shore unattenuated surge conditions, the maximum surge height is related to the initial input surge intensity. To maintain a stable positive correlation, the relationship can be expressed as follows:

8. A system for simulating multi-form composite tsunami surges using a double-dam-break model, based on the method described in any one of claims 1 to 7, characterized in that, include: A dual-dam-break physical model unit for generating multi-form composite tsunami surges, the dual-dam-break physical model unit comprising: The physics experimental water tank has a sloping bank at its downstream end. The first gate is located in the experimental water tank, upstream of the sloping bank, and is used to divide the experimental water tank into a downstream still water area and an upstream reservoir area. The second gate is located in the upstream reservoir area and is used to further divide the upstream reservoir area into the first reservoir and the second reservoir. The first gate and the second gate are respectively connected to a gate control device, which is used to control the opening sequence, opening speed and opening height of the two gates; The data acquisition unit is set up on the experimental water tank and the sloping bank to collect the wave height, flow velocity and pressure parameters of the surge wave; The ISPH numerical simulation unit is used to establish a two-dimensional numerical flume model corresponding to the double-dam-break physical model unit, and to perform numerical simulation of the generation and propagation process of the composite tsunami surge based on the incompressible smooth particle hydrodynamics ISPH method.

9. The system for simulating multi-form composite tsunami surge waves using the double-dam-break model according to claim 8, characterized in that, The physical experiment tank has a total length of 33.4m, a width of 1.5m, and a height of 2m. A sand slope is constructed at the downstream end of the tank, with a 5-meter-long bank and a slope of 1:

25. The sand used is of particle size D. 50 It is made of 0.18mm sand, and the first gate is located 8.4 meters upstream of the sloping bank.

10. The system for simulating multi-form composite tsunami surge waves using the double-dam-break model according to claim 8, characterized in that, The two-dimensional numerical flume model has a total length of 33.6m and a height of 1.1m. The sloping bank is located at the downstream end of the flume with a slope of 1:

25. The diameters of the numerical particles are set to 0.01 and 0.005, respectively, and the time step range is controlled within... arrive The simulation was run using 20 cores and 40 cores respectively. Multiple numerical wave height measurement points were set up at the toe of the slope and on the sloping bank at distances of 6m, 10.3m, and 13.3m from the toe of the slope. Numerical velocity measurement points were also set up at the toe of the slope to collect velocity data at the corresponding locations during the simulation.

Images