A numerical simulation method for vortex-induced motion of a double-tube suspended tunnel

Abstract

The present invention provides a numerical simulation method for vortex-induced motion of a double-tube suspended tunnel, including: creating a geometric model of the suspended tunnel structure and the external flow field calculation domain; meshing the suspended tunnel model calculation domain; combining the computational fluid dynamics model with the structural dynamics model to perform fluid-solid coupling numerical calculations, and performing information exchange between the fluid and the structure based on a weak coupling method and coordinate mapping; and post-processing the calculated data after the simulation reaches the termination time. The displacement, velocity, acceleration and hydrodynamic characteristics of the suspended tunnel are obtained by the method of the present invention, and the accurate prediction of the vortex-induced motion response of the suspended tunnel can be achieved, providing a high-precision numerical method for the analysis and design of the suspended tunnel, and providing strong support for the design improvement and performance enhancement of the suspended tunnel.

Description

Technical Field

[0001] The invention relates to the technical field of fluid-solid coupling numerical simulation, and in particular to a numerical calculation method for vortex-induced motion of a double-tube suspended tunnel based on a high-fidelity spectral unit method. Background Art

[0002] As a classic fluid-structure interaction (FSI) phenomenon, vortex induced motion (VIM) refers to the structural movement caused by periodic vortex shedding. Under certain conditions, the fluid flowing through a blunt body (such as a cylinder) may cause the alternating shedding of downstream vortices, namely the Karman vortex street. The alternating shedding of the wake vortices will generate periodic fluid forces on the object, resulting in movement transverse to the flow. The movement of the structure will change the flow pattern of the wake, which in turn further changes the fluid forces on the structure. When the frequency of vortex shedding is close to the natural frequency of the structure, the amplitude of the structure increases significantly under the influence of resonance. This phenomenon is also called locking. Studies have shown that vortex induced motion is one of the main causes of fatigue failure of marine engineering structures.

[0003] In recent years, with the continuous improvement of computer hardware performance and the rapid development of numerical simulation technology, the use of numerical simulation methods to solve practical engineering problems has received widespread attention. Previously, domestic and foreign scholars have conducted a large number of numerical studies on different fluid-solid coupling problems. The accuracy of existing numerical techniques is limited, and the cost of experimental methods is high.

[0004] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0005] The present invention aims to provide a numerical simulation method for vortex-induced motion of a double-tube suspended tunnel, which provides key support for the design improvement and performance enhancement of the suspended tunnel by predicting the vortex-induced motion response of the tunnel under the action of fluid with high accuracy.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A numerical simulation method for vortex-induced motion of a double-tube suspended tunnel comprises the following steps:

[0008] Step 1: Create a three-dimensional geometric model of a double-tube suspended tunnel structure, wherein the upstream of the double-tube suspended tunnel is a free flow area, and the downstream is a wake area where vortex shedding occurs;

[0009] Step 2: Divide the computational domain into grids and encrypt the radial grids and the wake area grids of the suspended tunnel;

[0010] Step 3: Using the computational fluid dynamics (CFD) method, the flow field around the suspension tunnel is simulated by solving the unsteady incompressible Navier-Stokes NS equations to obtain a computational fluid dynamics model;

[0011] Step 4: Establish a structural dynamics model of vortex-induced motion of a double-tube suspended tunnel, rigidly connect the suspended tunnels, and couple the structural dynamics model with the computational fluid dynamics model; determine the initial conditions and boundary conditions, initialize the calculation parameters, and carry out numerical simulation; integrate the pressure term and viscous stress term calculated by the CFD model along the structural surface to obtain the fluid force on the suspended tunnel, and bring the obtained fluid force into the structural dynamics model;

[0012] Step 5: Solve the structural dynamics model using the Newmark-Beta method to obtain the displacement, velocity and acceleration information of the suspended tunnel movement; determine whether the termination time has been reached. If the termination time has not been reached, update the coordinate mapping information and repeat steps 3-5 to solve the next time step;

[0013] Step 6: When the simulation reaches the end time, the calculated data is post-processed to extract the displacement, velocity, acceleration response and fluid force of the suspended tunnel.

[0014] Further:

[0015] In the three-dimensional geometric model created in step 1, the distance between the entrance boundary of the external flow field calculation domain and the center of the suspended tunnel is greater than or equal to 20 times the diameter of the tunnel cylinder, the distance between the exit boundary of the external flow field calculation domain and the center of the suspended tunnel is greater than or equal to 20 times the diameter of the tunnel cylinder, the distance between the exit of the external flow field calculation domain and the center of the suspended tunnel is greater than or equal to 40 times the diameter of the tunnel cylinder, and the ratio of the spanwise length to the tunnel cylinder diameter is determined according to the actual need to simulate the vortex-induced motion of the suspended tunnel.

[0016] The entrance boundary of the external flow field calculation domain is 20 times the diameter of the tunnel cylinder from the center of the suspended tunnel, the lateral boundaries on both sides of the external flow field calculation domain are 20 times the diameter of the tunnel cylinder from the center of the suspended tunnel, the exit boundary of the external flow field calculation domain is 40 times the diameter of the suspension tunnel center, and the ratio of the span length to the tunnel cylinder diameter is 2π.

[0017] In step 2, when meshing the computational domain, the height of the first layer of mesh in the radial direction of the suspended tunnel surface satisfies y + ≤1, and also meets the requirements of dissipation scale.

[0018] In step 3, the Navier-Stokes NS equations are discretized using the spectral unit method, and the velocity field and pressure field are decoupled using a high-order splitting algorithm based on a hybrid rigid stable format, so as to separately solve the nonlinear convection term, pressure term and linear diffusion term, where the convection term is processed in an explicit format, while the pressure term and diffusion term are discretized in an implicit format.

[0019] In step 4, the structure is simplified into a single spring oscillator system, and the structural dynamics model of its motion is

[0020]

[0021] Among them, η, and are the downstream displacement, downstream velocity and downstream acceleration of the structure, ζ, and are the transverse displacement, transverse velocity and transverse acceleration of the structure, ω N , ξ, and m are the natural angular frequency, damping ratio, and mass per unit length of the structure, respectively. D is the component of the fluid force acting on the structure in the downstream direction, i.e., resistance, F L It is the component of the fluid force on the structure in the transverse direction, that is, the lift; the following boundary conditions and initial conditions are adopted: the inlet boundary adopts the velocity inlet boundary condition, the outlet boundary uses the pressure outlet boundary condition, the lateral boundary condition uses the free slip boundary condition, the surface of the suspended tunnel is a no-slip boundary condition, the spanwise boundary condition uses the periodic boundary condition, and the suspended tunnel is initially in a stationary state.

[0022] In step 5, the Newmark-Beta method is used to relate the displacement, velocity and acceleration of the nth step and the n+1th step in the following way:

[0023]

[0024] Among them, suitable integral parameters are selected as J=2, α0=2, α1=-1 / 2, β0=2, β1=-1, γ0=3 / 2.

[0025] In step 6, the Q criterion is used to identify the three-dimensional tail vortex structure of the suspended tunnel, and the vortex leakage pattern of each spanwise section is represented by the vorticity field.

[0026] Step 6 also includes studying the tail vortex structure of the suspended tunnel and the vortex release pattern of each spanwise section based on flow field visualization technology.

[0027] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the numerical simulation method for vortex-induced motion of a double-tube suspended tunnel.

[0028] The present invention has the following beneficial effects:

[0029] The present invention provides a numerical simulation method for vortex-induced motion of a double-tube suspended tunnel, including: creating a geometric model of the suspended tunnel structure and the external flow field calculation domain; meshing the suspended tunnel model calculation domain; combining the computational fluid dynamics model with the structural dynamics model to perform fluid-solid coupling numerical calculation, and performing information exchange between the fluid and the structure based on the weak coupling method and coordinate mapping; and post-processing the calculated data after the simulation reaches the termination time. The displacement, velocity, acceleration and hydrodynamic characteristics of the suspended tunnel are obtained by the method of the present invention, and the accurate prediction of the vortex-induced motion response of the suspended tunnel can be achieved, providing a high-precision numerical method for the analysis and design of the suspended tunnel.

[0030] The embodiments of the present invention show significant differences and advantages over the prior art in numerical simulation of vortex-induced motion of suspended tunnels. Specifically, the present invention can provide high-precision prediction of vortex-induced motion response and mechanical properties of suspended tunnels, as well as in-depth mechanism analysis and research. The advantages of the present invention over the prior art are:

[0031] 1. In engineering, the vortex-induced motion flow field of a real suspended tunnel has a strong three-dimensional characteristic. The three-dimensional numerical simulation method provided by the embodiment of the present invention can capture the motion characteristics of the structure and the three-dimensional characteristics of the flow field with high precision.

[0032] 2. In solving the fluid-solid coupling problem under high Reynolds number, the numerical simulation method of the embodiment of the present invention has higher accuracy than the large eddy simulation method and the Reynolds average method.

[0033] In summary, the vortex-induced motion numerical simulation method of the double-tube suspended tunnel provided by the present invention can predict the vortex-induced motion response of the tunnel under the action of fluid with high accuracy, thereby providing key support for the design improvement and performance enhancement of the suspended tunnel.

[0034] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to an embodiment of the present invention.

[0036] Figure 2 Schematic diagram of vortex-induced motion characteristics of a double-tube suspended tunnel according to an embodiment of the present invention.

[0037] Figure 3a-Figure 3b The mesh division of the suspended tunnel structure and the external flow field calculation domain in the embodiment of the present invention and the encryption processing of the radial mesh and the wake area mesh therein are respectively shown.

[0038] Figure 4a-4bThey are respectively the displacement time history curves in the downstream direction and the cross-stream direction of the double-tube suspended tunnel under vortex-induced motion simulated in an embodiment of the present invention.

[0039] Figure 5a-5e They are respectively the three-dimensional tail vortex structure of the vortex-induced motion of the double-tube suspended tunnel and the vortex release pattern diagrams in different spanwise sections obtained based on the flow field visualization technology in the embodiments of the present invention. DETAILED DESCRIPTION

[0040] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0041] The embodiment of the present invention provides a numerical simulation method for vortex-induced motion of a double-tube suspended tunnel, comprising the following steps:

[0042] Step 1: Create a three-dimensional geometric model of a double-tube suspended tunnel structure, wherein the upstream of the double-tube suspended tunnel is a free flow area, and the downstream is a wake area where vortex shedding occurs;

[0043] Step 2: Divide the computational domain into grids and encrypt the radial grids and the wake area grids of the suspended tunnel;

[0044] Step 3: Using the computational fluid dynamics (CFD) method, the flow field around the suspension tunnel is simulated by solving the unsteady incompressible Navier-Stokes NS equations to obtain a computational fluid dynamics model;

[0045] Step 4: Establish a structural dynamics model of vortex-induced motion of a double-tube suspended tunnel, rigidly connect the suspended tunnels, and couple the structural dynamics model with the computational fluid dynamics model; determine the initial conditions and boundary conditions, initialize the calculation parameters, and carry out numerical simulation; integrate the pressure term and viscous stress term calculated by the CFD model along the structural surface to obtain the fluid force on the suspended tunnel, and bring the obtained fluid force into the structural dynamics model;

[0046] Step 5: Solve the structural dynamics model using the Newmark-Beta method to obtain the displacement, velocity and acceleration information of the suspended tunnel movement; determine whether the termination time has been reached. If the termination time has not been reached, update the coordinate mapping information and repeat steps 3-5 to solve the next time step;

[0047] Step 6: When the simulation reaches the end time, the calculated data is post-processed to extract the displacement, velocity, acceleration response and fluid force of the suspended tunnel.

[0048] In the numerical simulation method of vortex-induced motion of a double-tube suspended tunnel of the present invention, a geometric model of a suspended tunnel structure and an external flow field calculation domain is created, the calculation domain of the suspended tunnel model is gridded, the computational fluid dynamics model is combined with the structural dynamics model to perform fluid-solid coupling numerical calculation, information exchange between the fluid and the structure is performed based on a weak coupling method and coordinate mapping, and after the simulation reaches a termination time, the calculated data is post-processed to obtain the displacement, velocity, acceleration and hydrodynamic characteristics of the suspended tunnel, thereby achieving a high-precision prediction of the vortex-induced motion response of the suspended tunnel under the action of the fluid, providing a high-precision numerical simulation method for the analysis and design of the suspended tunnel, thereby providing strong support for the design improvement and performance enhancement of the suspended tunnel.

[0049] The specific embodiments of the present invention are further described below.

[0050] In this embodiment, all parameters are dimensionless. The dimensionless diameter D of the suspended tunnel structure is 1, and the incoming flow velocity U ∞ is 1, the stiffness k of the system is 2.4805, the span length is 2πD, and the mass ratio m * =1, the system structure damping coefficient is c=0.

[0051] The basic steps of this embodiment are as follows: Figure 1 As shown:

[0052] Step 1: Create a three-dimensional geometric model of the suspended tunnel structure, based on the geometric dimensions of the double-tube suspended tunnel. The upstream of the double-tube suspended tunnel is the free flow area, and the downstream is the wake area where vortex shedding occurs. Preferably, in step 1, the entrance boundary of the external flow field calculation domain is 20 times the diameter from the center of the suspended tunnel, the lateral boundaries on both sides are 20 times the diameter from the center of the suspended tunnel, the exit boundary is 40 times the diameter from the center of the suspended tunnel, and the ratio of the span length to the diameter of the suspended tunnel is 2π.

[0053] Step 2: Based on the open source software Gmsh, the computational domain is meshed and the radial mesh and the wake area mesh of the suspended tunnel are encrypted. Figure 3a and Figure 3b The height of the first layer of mesh in the radial direction of the suspended tunnel surface satisfies y + ≤1, and also meets the requirements of dissipation scale.

[0054] Step 3: The open source computational fluid dynamics code Nektar++ is used to solve the flow field control equations. The flow field around the suspended tunnel is solved using the unsteady incompressible Navier-Stokes (NS) equations. The fluid control equations are discretized using the spectral / hp element method. The velocity field and pressure field are decoupled using a high-order stiffly stable splitting scheme based on a hybrid rigid stable format, thereby separately solving the nonlinear convection term, pressure term, and linear diffusion term. The convection term is processed in an explicit format, while the pressure term and diffusion term are discretized in an implicit format.

[0055] Step 4: Establish the structural dynamics model of the vortex-induced motion of the suspended tunnel. Due to the existence of rigid constraints, the vibrations of the two suspended tunnels are completely synchronized, so the structure is simplified into a single spring oscillator system:

[0056]

[0057] In the formula, η, and are the downstream displacement, downstream velocity and downstream acceleration of the structure, ζ, and are the transverse displacement, transverse velocity and transverse acceleration of the structure, ω N , ξ, and m are the natural angular frequency, damping ratio, and mass per unit length of the structure, respectively. D is the component of the fluid force acting on the structure in the downstream direction, i.e., resistance, F L It is the component of the fluid force on the structure in the transverse direction, that is, the lift. The boundary conditions for calculation are as follows: the inlet uses the velocity boundary condition, the outlet uses the pressure outlet boundary condition, the lateral boundary condition uses the free slip boundary condition, and the surface of the suspended tunnel uses the no-slip boundary condition. The suspended tunnel is initially in a stationary state.

[0058] Step 5: Use the Newmark-Beta method to relate the displacement, velocity, and acceleration of the nth step to the n+1th step as follows:

[0059]

[0060]

[0061] Select appropriate integration parameters J=2, α0=2, α1=-1 / 2, β0=2, β1=-1, γ0=3 / 2.

[0062] It is determined whether the termination time has been reached. If the termination time has not been reached, the coordinate mapping information is updated and the process returns to step 3. Steps 3-5 are repeated under the updated coordinate mapping to solve the next time step.

[0063] Step 6: After the simulation reaches the end time, the calculated data is post-processed to extract the displacement, velocity, acceleration response and fluid force of the suspended tunnel. In this example, the time history curve of the downstream displacement of the vortex-induced motion of the suspended tunnel under elastic support is as follows: Figure 4a As shown in the figure, the time history curve of the transverse displacement of the vortex-induced motion of the suspended tunnel under elastic support is shown in Figure 4b At the same time, based on the flow field visualization software Paraview, the Q criterion is used to identify the three-dimensional tail vortex structure of the suspended tunnel, and the vortex discharge mode of each spanwise section is represented by the vortex field. In this example, the three-dimensional tail vortex structure of the vortex-induced motion of the suspended tunnel is shown in Figure 5a As shown in the figure, the vortex discharge pattern at the bottom section of the suspended tunnel is as follows: Figure 5b As shown, the vortex release mode at the z / 4 section of the suspension tunnel is as follows: Figure 5c As shown, the vortex leakage mode at the z / 2 section of the suspension tunnel is as follows: Figure 5d As shown, the vortex release mode at the 3z / 4 section of the suspension tunnel is as follows: Figure 5e shown.

[0064] In summary, the present invention provides a numerical simulation method for vortex-induced motion of a double-tube suspended tunnel. The displacement, velocity, acceleration and hydrodynamic characteristics of the suspended tunnel are obtained by the method of the present invention, which can accurately predict the vortex-induced motion response of the suspended tunnel, and provide a high-precision numerical method for the analysis and design of the suspended tunnel. The embodiments of the present invention show significant differences and advantages compared with the prior art in dealing with the numerical simulation of vortex-induced motion of suspended tunnels. Specifically, the present invention can provide high-precision prediction of the vortex-induced motion response and mechanical characteristics of suspended tunnels, as well as in-depth mechanism analysis and research. The advantages of the present invention compared with the prior art are as follows: 1. In engineering, the vortex-induced motion flow field of a real suspended tunnel has a strong three-dimensional characteristic. The three-dimensional numerical simulation method provided by the embodiment of the present invention can capture the motion characteristics of the structure and the three-dimensional characteristics of the flow field with high precision. 2. In solving the fluid-solid coupling problem under high Reynolds number, the numerical simulation method of the embodiment of the present invention is more accurate than the large eddy simulation method and the Reynolds average method.

[0065] In summary, the vortex-induced motion numerical simulation method of the double-tube suspended tunnel provided by the present invention can predict the vortex-induced motion response of the tunnel under the action of fluid with high accuracy, thereby providing key support for the design improvement and performance enhancement of the suspended tunnel.

[0066] An embodiment of the present invention further provides a storage medium for storing a computer program, which at least performs the above method when executed.

[0067] An embodiment of the present invention further provides a control device, comprising a processor and a storage medium for storing a computer program; wherein the processor is configured to execute at least the method described above when executing the computer program.

[0068] An embodiment of the present invention further provides a processor, wherein the processor executes a computer program and at least executes the method described above.

[0069] The storage medium can be implemented by any type of non-volatile storage device, or a combination thereof. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic random access memory (FRAM), a ferromagnetic random access memory (Flash Memory), a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM); the magnetic surface memory can be a disk memory or a tape memory. The storage medium described in the embodiments of the present invention is intended to include, but is not limited to, these and any other suitable types of memory.

[0070] In the several embodiments provided by the present invention, it should be understood that the disclosed systems and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0071] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0072] In addition, all functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately used as a unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0073] A person skilled in the art can understand that: all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), disks or optical disks, etc. Various media that can store program codes.

[0074] Alternatively, if the above-mentioned integrated unit of the present invention is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present invention can be essentially or partly reflected in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, RAM, magnetic disks or optical disks.

[0075] The methods disclosed in the several method embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments.

[0076] The features disclosed in several product embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new product embodiments.

[0077] The features disclosed in several method or device embodiments provided by the present invention can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0078] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A numerical simulation method for vortex-induced motion of a double-tube suspended tunnel, characterized in that: The steps include: Step 1: Create a three-dimensional geometric model of a double-tube suspended tunnel structure, wherein the upstream of the double-tube suspended tunnel is a free flow area, and the downstream is a wake area where vortex shedding occurs; Step 2: Divide the computational domain into grids and encrypt the radial grids and the wake area grids of the suspended tunnel; Step 3: Using the computational fluid dynamics (CFD) method, the flow field around the suspension tunnel is simulated by solving the unsteady incompressible Navier-Stokes NS equations to obtain a computational fluid dynamics model; Step 4: Establish a structural dynamics model of vortex-induced motion of a double-tube suspended tunnel, rigidly connect the suspended tunnels, and couple the structural dynamics model with the computational fluid dynamics model; determine the initial conditions and boundary conditions, initialize the calculation parameters, and carry out numerical simulation; The pressure term and the viscous stress term calculated by the CFD model are integrated along the surface of the structure to obtain the fluid force on the suspended tunnel, and the obtained fluid force is brought into the structural dynamics model; Step 5: Solve the structural dynamics model using the Newmark-Beta method to obtain the displacement, velocity and acceleration information of the suspended tunnel movement; determine whether the termination time has been reached. If the termination time has not been reached, update the coordinate mapping information and repeat steps 3-5 to solve the next time step; Step 6: When the simulation reaches the end time, the calculated data is post-processed to extract the displacement, velocity, acceleration response and fluid force of the suspended tunnel; In step 4, the structure is simplified into a single spring oscillator system, and the structural dynamics model of its motion is Among them, η, and are the downstream displacement, downstream velocity and downstream acceleration of the structure, ζ, and are the transverse displacement, transverse velocity and transverse acceleration of the structure, ω N , ξ, and m are the natural angular frequency, damping ratio, and mass per unit length of the structure, respectively. D is the component of the fluid force acting on the structure in the downstream direction, i.e., resistance, F L It is the component of the fluid force on the structure in the transverse direction, that is, the lift. The following boundary conditions and initial conditions are adopted: the inlet boundary adopts the velocity inlet boundary condition, the outlet boundary uses the pressure outlet boundary condition, the lateral boundary condition uses the free slip boundary condition, the surface of the suspended tunnel is the no-slip boundary condition, the spanwise boundary condition uses the periodic boundary condition, and the suspended tunnel is initially in a stationary state. In step 5, the Newmark-Beta method is used to relate the displacement, velocity and acceleration of the nth step and the n+1th step in the following way: Among them, J, α0, α1, β0, β1, and γ0 are integration parameters.

2. The numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to claim 1, characterized in that: In the three-dimensional geometric model created in step 1, the distance between the entrance boundary of the external flow field calculation domain and the center of the suspended tunnel is greater than or equal to 20 times the diameter of the tunnel cylinder, the distance between the exit boundary of the external flow field calculation domain and the center of the suspended tunnel is greater than or equal to 20 times the diameter of the tunnel cylinder, the distance between the exit of the external flow field calculation domain and the center of the suspended tunnel is greater than or equal to 40 times the diameter of the tunnel cylinder, and the ratio of the spanwise length to the tunnel cylinder diameter is determined according to the actual need to simulate the vortex-induced motion of the suspended tunnel.

3. The numerical simulation method of vortex-induced motion of a double-tube suspended tunnel according to claim 2, characterized in that: The entrance boundary of the external flow field calculation domain is 20 times the diameter of the tunnel cylinder from the center of the suspended tunnel, the lateral boundaries on both sides of the external flow field calculation domain are 20 times the diameter of the tunnel cylinder from the center of the suspended tunnel, the exit boundary of the external flow field calculation domain is 40 times the diameter of the suspension tunnel center, and the ratio of the span length to the tunnel cylinder diameter is 2π.

4. The numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to any one of claims 1 to 3, characterized in that: In step 2, when meshing the computational domain, the height of the first layer of mesh in the radial direction of the suspended tunnel surface satisfies y + ≤1, and also meets the requirements of dissipation scale.

5. The numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to any one of claims 1 to 3, characterized in that: In step 3, the Navier-Stokes NS equations are discretized using the spectral unit method, and the velocity field and pressure field are decoupled using a high-order splitting algorithm based on a hybrid rigid stable format, so as to separately solve the nonlinear convection term, pressure term and linear diffusion term, where the convection term is processed in an explicit format, while the pressure term and diffusion term are discretized in an implicit format.

6. The numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to any one of claims 1 to 3, characterized in that: In step 5, the integration parameters J=2, α0=2, α1=-1 / 2, β0=2, β1=-1, γ0=3 / 2.

7. The numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to any one of claims 1 to 3, characterized in that: In step 6, the Q criterion is used to identify the three-dimensional tail vortex structure of the suspended tunnel, and the vortex leakage pattern of each spanwise section is represented by the vorticity field.

8. The numerical simulation method for vortex-induced motion of a double-tube suspended tunnel according to any one of claims 1 to 3, characterized in that: Step 6 also includes studying the tail vortex structure of the suspended tunnel and the vortex release pattern of each spanwise section based on flow field visualization technology.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the numerical simulation method for vortex-induced motion of a double-tube suspended tunnel as described in any one of claims 1 to 8 is implemented.

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