An inland waterway virtual design method based on ship-flow field coupling

Abstract

The application discloses an inland waterway virtual design method based on ship-flow field coupling, comprising the following steps: determining ship information and flow field conditions; the ship information at least comprises a ship type and a ship position; the flow field conditions at least comprise a water flow speed, riverbed information and navigation-obstructing structure information; performing ship hydrodynamic response calculation; performing ship motion trajectory analysis on ships of various ship types, and using analysis results for inland waterway virtual design. In the channel design process, the application fully considers the interaction between the ship and the flow field, can make the ship effectively avoid risk oblique flow and rapid flow, and reasonably utilize water flow kinetic energy, so as to improve the safety and economy of ship navigation.

Description

Technical Field

[0001] This invention belongs to the field of inland waterway design, specifically relating to a virtual design method for inland waterways based on ship-flow field coupling. Background Technology

[0002] Waterways generally refer to navigable waterways within rivers and canals. Safety and fuel economy are two key factors to consider in waterway design. Specifically, avoiding collisions with obstructions and effectively utilizing flow field kinetic energy are critical issues that inland waterway design needs to address. With the implementation of waterway engineering projects such as dredging and runoff regulation, the flow field conditions for ship navigation have changed, resulting in numerous waterways awaiting planning or requiring optimization. Currently, inland waterway planning and design research largely relies on the experience of engineers, that is, conducting waterway planning by analyzing and summarizing the evolution patterns of the flow field within the waterway. However, the service target of waterways is ships, and existing technologies do not fully consider the interaction between ships and the flow field during the waterway design process. Summary of the Invention

[0003] The purpose of this invention is to provide a virtual design method for inland waterways based on the coupling effect between ships and flow fields. This method fully considers the interaction between ships and flow fields during the waterway design process, enabling ships to effectively avoid risks such as oblique currents and rapid currents, and to make reasonable use of water kinetic energy, thereby improving the safety and economy of ship navigation.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a virtual design method for inland waterways based on ship-flow field coupling, comprising the following steps:

[0005] S1. Determine vessel information and flow field conditions; vessel information should include at least the vessel type and position; flow field conditions should include at least the water velocity, riverbed information, and information on obstructing structures.

[0006] S2. Perform ship hydrodynamic response calculations. The specific steps are as follows:

[0007] S2.1. Establish a fluid calculation model based on ship information and flow field conditions, and discretize the computational domain in the fluid calculation model into a grid.

[0008] S2.2 Keep the ship stationary, set the inlet velocity of the flow field and perform simulation numerical calculations until the residual value obtained from the simulation numerical calculations reaches the preset value, and use the ship information and flow field conditions at this time as the initial flow field setting data;

[0009] S2.3. Release the ship from its stationary state, allow the ship to interact with the initial flow field, obtain the ship's trajectory, and calculate the ship's hydrodynamic response motion process under the flow field;

[0010] S3. Analyze the motion trajectories of ships of various types and use the analysis results for virtual design of inland waterways.

[0011] The method used in S2.3 to calculate the hydrodynamic response motion of a ship under a flow field is a fluid-structure interaction calculation method.

[0012] S2.3 specifically refers to:

[0013] S2.31. Integrate the water pressure on the ship surface in the initial flow field data to obtain the hydrodynamic force on the ship;

[0014] S2.32. Establish the ship dynamics equations and solve them to obtain the speed, displacement and trajectory of the ship during its motion in the inland waterway.

[0015] S2.33. Update the computational domain mesh for ship position and flow field using dynamic meshing technology;

[0016] S2.34. Perform iterative calculations to obtain the ship's trajectory.

[0017] The ship dynamics equations are as follows:

[0018] Ma+M a a=F+M a a

[0019] In the formula, M and M a Let be the mass and added mass matrices of the ship, respectively; let a be the acceleration vector of the ship; and let F be the resultant force vector acting on the ship.

[0020] The settings for mesh reconstruction in dynamic mesh technology include at least the mesh update method, minimum mesh size, and maximum mesh skewness.

[0021] The boundary conditions of the computational domain in S2.1 are set as follows: the inlet and outlet of the fluid computational domain are set to velocity-inlet and pressure-outlet, respectively, and the boundary of the fluid domain and the ship surface are set to wall.

[0022] S3 specifically involves: processing the ship motion trajectories of various ship types, dividing the ship motion trajectory curves of various ship types into two groups based on different initial positions of the ships; using the weighted least squares method to fit the two sets of curves respectively, that is, assigning different weights to the motion trajectories of each ship type according to the frequency of navigation of each ship type in the target waterway, and then using the least squares method to fit the curves, and using the two fitted curves as the channel boundary line, and using the channel boundary line as the output value of the virtual design of the inland waterway.

[0023] The inland waterway was virtually designed using the general-purpose computational fluid dynamics software FLUENT.

[0024] A computer device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, performs the steps of the method as described in any of the preceding claims.

[0025] A computer-readable storage medium is also provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the method as described in any of the preceding claims.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) This invention takes the ship as the main factor into the channel planning and design research, which can effectively avoid oblique currents and rapid currents and improve the safety of ship navigation.

[0028] (2) The waterway designed in this invention can improve the fuel economy of ships by utilizing the kinetic energy of the flow field;

[0029] (3) This algorithm realizes the simulation of ship motion under large scale and large displacement, and overcomes the shortcomings of existing commercial software and methods that are prone to divergence and non-convergence when dealing with this problem;

[0030] (4) This algorithm realizes the real-time description of the speed, displacement and trajectory of the ship during navigation. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the velocity time-history curve in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the displacement time history curve in an embodiment of the present invention;

[0034] Figure 4 This is a waterway planning and design diagram in an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] This embodiment simulates the drifting motion of a vessel in an inland waterway (Dongliu section). In this embodiment, the vessel's total length is 25.9m and its beam is 4.6m. This embodiment uses the general-purpose computational fluid dynamics software FLUENT to solve for the vessel's motion in the inland waterway section, and the calculation results are used for waterway design. The virtual design process is detailed below:

[0037] S1. Determine the ship type, initial position, and flow field conditions. To improve the reliability and applicability of the designed waterway, multiple ship types are selected for calculation. For the same type of vessel, two initial positions are selected as calculation conditions. These two initial positions are close to both banks of the river channel and are the extreme positions that allow the ship to navigate (determined by the channel depth and other limiting conditions). In addition, it is also necessary to obtain information on the water flow speed and obstructing structures in the waterway.

[0038] S2. Perform ship hydrodynamic response calculations. The specific steps are as follows:

[0039] S2.1. Establish a numerical model based on the ship information and flow field conditions determined in S1. Discretize the computational domain into a grid, and set the boundary conditions as follows: set the inlet and outlet of the fluid computational domain as velocity-inlet and pressure-outlet, respectively, and set the boundary of the fluid domain and the ship surface as wall. Figure 3 The numerical model is used as an example.

[0040] S2.2 Obtaining the Initial Flow Field. When the ship is in the fluid computation domain, the initial information of the flow field needs to be obtained first. That is, keep the ship in a stationary state, set the inlet velocity of the flow field for calculation, and obtain the initial flow field after the numerical calculation is stable (the condition for numerical calculation stability can be that the residual value obtained from the simulation numerical calculation reaches the preset value, or the resistance on the ship is stable at a certain value or changes periodically, or the resistance on the oasis in the ship's navigation segment is stable. All of the above conditions can be used to judge the stability of numerical calculation).

[0041] S2.3 Calculate the hydrodynamic response of the ship under the flow field. Release the stationary ship in step (2) and allow it to interact with the flow field to obtain the ship's trajectory. The fluid-structure interaction calculation method is used to carry out the calculation, and the calculation process in each time step is described as follows:

[0042] S2.31. Based on the calculated flow field information, the water pressure on the ship surface is integrated to obtain the hydrodynamic force on the ship.

[0043] S2.32. Due to the high density of water, the additional mass effect during ship motion cannot be ignored. The ship dynamics equations are as follows:

[0044] Ma+M a a=F+M a a

[0045] In the formula, M, M a Let be the mass and added mass matrices of the ship, 'a' be the acceleration vector, and 'F' be the resultant force vector acting on the ship. By simultaneously solving the constraint expressions and dynamic equations, the velocity, displacement, and trajectory of the ship during its motion in inland waterways can be obtained. Using C language, the calculations in steps a and b are programmed and imported into FLUENT through the user-defined function (UDF) module to complete the calculation of the ship's hydrodynamics and the solution of the dynamic equations.

[0046] S2.33. Update the computational domain mesh for the ship's position and flow field using dynamic meshing technology. Complete the mesh reconstruction settings in FLUENT's dynamic meshing settings, including mesh update method, minimum mesh size, and maximum mesh skewness.

[0047] S2.34. Iterative Calculation. Based on the result of step c, perform calculations for the next time step, repeating steps a and c until the ship's motion process is completed, and obtain the ship's trajectory.

[0048] S3. Multi-ship trajectory analysis based on weighted least squares method, and application of the analysis results to waterway design. The obtained multi-ship trajectories are processed, and the trajectory curves are divided into two groups based on different initial ship positions. Weighted least squares method is used to fit the two sets of curves separately. Specifically, different weights are assigned to the trajectories of each ship type according to their navigation frequency within the target section, and then least squares method is used for curve fitting. The two fitted curves are used as the waterway boundary lines, thus completing the virtual design of the inland waterway based on ship-flow field coupling. Figure 2 and Figure 3 These are the velocity time-history curve and displacement time-history curve of this embodiment, respectively. Figure 4 The diagram shows the waterway planning and design for an embodiment, where the dashed line represents the existing waterway and the solid line represents the waterway designed by the present invention based on the coupling effect between the ship and the flow field.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A virtual design method for inland waterways based on ship-flow field coupling, characterized in that, Includes the following steps: S1. Determine vessel information and flow field conditions; vessel information should include at least the vessel type and position; flow field conditions should include at least the water velocity, riverbed information, and information on obstructing structures. S2. Perform ship hydrodynamic response calculations. The specific steps are as follows: S2.

1. Establish a fluid calculation model based on ship information and flow field conditions, and discretize the computational domain in the fluid calculation model into a grid. S2.2 Keep the ship stationary, set the inlet velocity of the flow field and perform simulation numerical calculations until the residual value obtained from the simulation numerical calculations reaches the preset value, and use the ship information and flow field conditions at this time as the initial flow field setting data; S2.

3. Release the ship from its stationary state, allow the ship to interact with the initial flow field, calculate the ship's hydrodynamic response motion process under the flow field, and obtain the ship's motion trajectory; S3. Analyze the motion trajectories of ships of various types and use the analysis results for virtual design of inland waterways.

2. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 1, characterized in that, The method used in S2.3 to calculate the hydrodynamic response motion of a ship under a flow field is a fluid-structure interaction calculation method.

3. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 2, characterized in that, S2.3 specifically refers to: S2.

31. Integrate the water pressure on the ship surface in the initial flow field data to obtain the hydrodynamic force on the ship; S2.

32. Establish the ship dynamics equations and solve them to obtain the speed, displacement and trajectory of the ship during its motion in the inland waterway. S2.

33. Update the computational domain mesh for ship position and flow field using dynamic meshing technology; S2.

34. Perform iterative calculations to obtain the ship's trajectory.

4. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 3, characterized in that, The ship dynamics equations are as follows: Ma+M a a=F+M a a In the formula, M and M a Let be the mass and added mass matrices of the ship, respectively; let a be the acceleration vector of the ship; and let F be the resultant force vector acting on the ship.

5. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 3, characterized in that, The settings for mesh reconstruction in dynamic mesh technology include at least the mesh update method, minimum mesh size, and maximum mesh skewness.

6. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 1, characterized in that, The boundary conditions of the computational domain in S2.1 are set as follows: the inlet and outlet of the fluid computational domain are set to velocity-inlet and pressure-outlet, respectively, and the boundary of the fluid domain and the ship surface are set to wall.

7. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 1, characterized in that, S3 specifically involves: processing the ship motion trajectories of various ship types, dividing the ship motion trajectory curves of various ship types into two groups based on different initial positions of the ships; using the weighted least squares method to fit the two sets of curves respectively, that is, assigning different weights to the motion trajectories of each ship type according to the frequency of navigation of each ship type in the target waterway, and then using the least squares method to fit the curves, and using the two fitted curves as the channel boundary line, and using the channel boundary line as the output value of the virtual design of the inland waterway.

8. The virtual design method for inland waterways based on ship-flow field coupling as described in claim 1, characterized in that, The inland waterway was virtually designed using the general-purpose computational fluid dynamics software FLUENT.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-8.

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