A liquid surface grid modeling method for wave force analysis of a small water plane TLP wind turbine platform

Abstract

The application belongs to the field of hydrodynamic calculation of ocean engineering, and particularly relates to a liquid surface grid modeling method for wave force analysis of a small water plane TLP wind turbine platform, comprising the following steps: determining a free liquid surface outer radius and a high-density grid area radius; constructing a high-density area within the high-density grid area radius; taking the center of the wind turbine platform as an origin, constructing a star-shaped structured grid framework according to the number and layout of the platform columns, and performing grid division on the free liquid surface in the star-shaped structured grid framework according to the maximum grid length; establishing a transition area between the high-density grid area radius and the outer boundary of the transition area, and establishing an edge area between the outer boundary of the transition area and the free liquid surface outer radius; and performing grid division on the transition area and the edge area by using a concentric ring division method; and obtaining a free liquid surface calculation model based on the high-density area, the transition area and the edge area after grid division. The application can significantly improve the calculation accuracy of the second-order wave force under extreme sea conditions.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering hydrodynamic calculation, specifically relating to a liquid surface mesh modeling method for wave force analysis of a small waterplane area (TLP) wind turbine platform. Background Technology

[0002] Tension leg platforms (TLPs), as a key structural form in deep-sea marine engineering, possess significant advantages in fields such as deep-sea wind power development due to their high vertical stiffness and stable motion response. Among them, small waterplane area (SWA) TLPs further reduce the impact of first-order wave forces by decreasing the waterplane area, but their sensitivity to second-order wave forces also increases. Under complex sea conditions, nonlinear wave interactions can induce low-frequency difference forces, high-frequency sum forces, and mean drift forces. These second-order wave forces significantly amplify the platform's six-degree-of-freedom motion response, thereby affecting the safety of the mooring system and the structural fatigue life. Therefore, accurately predicting second-order wave forces is a core issue in ensuring the design reliability and extreme condition adaptability of SWATs.

[0003] Currently, in engineering practice, wave loads are typically calculated using potential flow theory combined with surface element methods (such as WADAM or WASIM modules), and second-order wave forces are solved using the far-field momentum method or the near-field pressure integral method. However, the accuracy of both methods is highly dependent on the mesh discretization quality of the wetted surface and free surface regions of the structure. Existing mesh generation techniques mainly focus on the fine modeling of the platform's main structure, while uniform or sparse mesh generation strategies are often used for the free surface region (especially areas near the waterline where wave potential gradients change drastically). This approach makes it difficult to accurately capture the spatial distribution characteristics of higher-order scattering potentials, leading to a significant increase in the calculation error of second-order wave forces under extreme sea states (such as deformed waves), which in turn affects the reliability of the platform's dynamic response assessment. Therefore, there is an urgent need for a technical solution that can optimize the mesh discretization accuracy of the free surface to improve the calculation accuracy of second-order wave forces at the small waterline TLP. Summary of the Invention

[0004] To address the aforementioned technical problems of insufficient mesh discretization accuracy, inability to accurately capture higher-order physical fields, and low reliability under extreme conditions, this invention provides a liquid surface mesh modeling method for wave force analysis of small waterplane area (TLP) wind turbine platforms. This invention primarily utilizes a high-density mesh generation method for the free liquid surface area near the columns beneath the platform. A star-shaped structured mesh is defined within this high-density mesh region. Transition and edge regions, established based on the concentric ring method, are set outside the high-density region. The mesh density in the transition and edge regions gradually decreases from the inside out, thereby ensuring computational accuracy and making the dimensions of the free liquid surface more consistent with wave propagation characteristics.

[0005] The technical means employed in this invention are as follows:

[0006] A method for liquid surface mesh modeling for wave force analysis of a small waterplane surface TLP wind turbine platform includes the following steps: Based on the column spacing and wave angular frequency of the small waterplane TLP fan platform, the outer radius of the free liquid surface and the radius of the high-density grid region are determined. Within the radius of the high-density grid area, a high-density zone is constructed. Taking the center of the wind turbine platform as the origin, a star-shaped structured grid frame is constructed based on the number and layout of the platform columns. According to the maximum grid length constrained by the maximum wave angular frequency, the free liquid surface in the star-shaped structured grid frame is divided into grids. The free liquid surface area between the star-shaped structured grid frame and the radius of the high-density grid area is also divided into grids. A transition zone is established between the radius of the high-density grid region and the outer boundary of the transition zone. An edge zone is established between the outer boundary of the transition zone and the outer radius of the free liquid surface. The transition zone and the edge zone are meshed using a method of dividing concentric rings. Based on the high-density region, transition region, and edge region after meshing, a free surface calculation model for analyzing wave forces is obtained.

[0007] Furthermore, the steps for establishing the star-shaped structured network framework include: There are six columns under the wind turbine platform. In the high-density area, parallelogram units of the same size and shape are built with each column under the wind turbine platform as the center. One acute vertex of each parallelogram unit coincides with the center of the wind turbine platform, and the length of the side adjacent to the acute vertex coincides with the side length of the adjacent parallelogram unit in the clockwise direction. Based on the six parallelogram units configured, a star-shaped structured network framework is constructed.

[0008] Furthermore, the mesh length in the star-shaped structured network framework is controlled to not exceed the maximum mesh length, and the formula for limiting the maximum mesh length is:

[0009] in, For the maximum grid length, It is the acceleration due to gravity. This represents the maximum wave angular frequency.

[0010] Furthermore, the formula for calculating the outer radius of the free liquid surface is:

[0011] in, The outer radius of the free liquid surface, The maximum horizontal length of the platform. It is the acceleration due to gravity. This is the minimum wave angular frequency.

[0012] Furthermore, the formula for calculating the radius of the high-density grid region is as follows:

[0013] in, The radius of the high-density grid region. Let be the radius of the circumcircle formed by all the columns beneath the TLP wind turbine platform. It is the acceleration due to gravity. The maximum wave angular frequency, This represents the truncation error.

[0014] Furthermore, the meshing steps for the transition region and edge region include: Based on the maximum number of grids on the free surface, the total number of grids in the high-density region, and the number of grids required for each concentric ring, combined with the set ring number ratio coefficient in the transition region, the number of concentric rings in the transition region is calculated:

[0015] in, To take the closest integer, This is the ratio coefficient of the number of rings in the transition zone. This represents the maximum number of grid cells for the free surface in the SESAM software. For all grid cells in the high-density region, The number of grid cells required for each concentric ring. The number of concentric rings in the transition zone; Based on the number of concentric rings in the transition zone, the maximum number of grids on the free surface, the total number of grids in the high-density zone, and the number of grids required for each concentric ring, calculate the number of concentric rings in the edge zone:

[0016] in, The number of concentric rings in the edge region; Define the radial stretching factor of the transition region, wherein the value of the radial stretching factor of the transition region ranges from 1.1 to 1.25; Define a radial stretching factor for the edge region, wherein the value of the radial stretching factor for the edge region ranges from 1.2 to 1.35; Calculate the outer radius of the first concentric ring in the transition region:

[0017] in, The outer radius of the first concentric ring in the transition zone. The outer radius of the free liquid surface, The radius of the high-density grid region. This is the radial stretching factor for the transition region. The radial stretching factor of the edge region. The number of concentric rings in the transition zone. The number of concentric rings in the edge region; Calculate the outer radius of the i-th concentric ring in the transition region:

[0018] in, Let be the outer radius of the i-th concentric ring in the transition region. Let be the radial stretching factor of the transition region of the i-th concentric ring in the transition region. The radius of the outer edge of the first concentric ring in the transition zone; Calculate the outer radius of the j-th concentric ring in the edge region:

[0019] in, Let be the outer radius of the j-th concentric ring in the edge region. The outer radius of the transition zone's outer boundary. Let be the radial stretching factor of the edge region of the j-th concentric ring in the transition region. The radius of the outer edge of the first concentric ring in the transition zone; The formula for calculating the outer radius of the outer boundary of the transition zone is:

[0020] in, The outer radius of the transition zone's outer boundary; Based on the outer radius of each concentric ring in the transition zone, the radius of the high-density grid region, and the outer radius of the outer boundary of the transition zone, the transition zone is divided into several concentric rings, and the transition zone after dividing into concentric rings is meshed. Based on the outer edge radius of each concentric ring in the edge region, the outer edge radius of the transition region, and the outer radius of the free liquid surface, the edge region is divided into several concentric rings, and the edge region after dividing into concentric rings is meshed.

[0021] Furthermore, when meshing the transition zone, along the radial rays emanating from the center of the platform and distributed at equal angular intervals, the intersection points of the radial rays and the concentric rings are found, and the intersection points are set as meshing nodes so that the nodes of adjacent concentric rings remain aligned in the radial direction. The grid size gradually increases from the radius of the high-density grid region to the outer boundary of the transition zone.

[0022] Furthermore, when meshing the edge region, the mesh size gradually increases from the outer boundary of the transition zone to the outer radius of the free liquid surface; The grid length of the outermost concentric ring in the edge region is less than or equal to 1 / 15 of the outer radius of the free liquid surface region.

[0023] Compared with the prior art, the present invention has the following advantages: 1. The multi-column TLP with a small waterline exhibits significant symmetry, with wave diffraction mainly concentrated in the columns and intercolumn regions. The star-shaped mesh expands radially along the main direction. This invention employs a hexagonal star-shaped mesh framework based on six columns, ensuring regular mesh shape and good continuity in high-density areas, significantly improving mesh quality and hydrodynamic calculation stability near the waterline. Furthermore, it guarantees that the free surface elements are regular parallelograms with consistent orientation and aligned arrangement.

[0024] 2. This invention sets up a gradually changing transition region and edge region, and combines it with a concentric ring partitioning strategy to make the mesh continuously change from dense to sparse. The radially gradually changing mesh of the concentric ring not only conforms to the radial attenuation characteristics of the wave field, but also realizes smooth size transition and regular alignment of units. This improves numerical stability and computational efficiency while ensuring near-field accuracy, and reduces numerical reflection, thereby ensuring computational accuracy.

[0025] 3. This invention achieves a reasonable setting of the calculation domain range by using the calculation formula for the outer radius of the free liquid surface, making the size of the free liquid surface area more consistent with the wave propagation characteristics, thereby improving the overall accuracy of the second-order wave force calculation.

[0026] 4. This invention overcomes the errors caused by coarse mesh division in existing technologies by precisely dividing the free surface region and the high-density mesh region. This method can more accurately capture the second-order wave forces generated by the nonlinear interaction of waves, especially under strong nonlinear conditions such as extreme sea states or abnormal waves, significantly improving calculation accuracy and enhancing the ability to analyze the response of difference frequency forces, sum frequency forces, and average drift forces.

[0027] 5. This invention provides a method for determining the radius of the encrypted region and the maximum grid size, thereby enabling precise encryption of the strongly nonlinear region near the platform and effectively improving the solution accuracy of the local wave potential and scattering field.

[0028] Based on the above reasons, this invention can be widely applied in fields such as marine engineering hydrodynamic calculations. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart illustrating the liquid surface mesh modeling method for wave force analysis of a small waterline TLP wind turbine platform according to the present invention.

[0031] Figure 2 This is a schematic diagram of the wet surface model of the small waterline TLP platform according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the mesh modeling of the high-density mesh region of the free liquid surface in an embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram illustrating the concentric ring division of the free liquid surface transition region and edge region in an embodiment of the present invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] like Figure 1 As shown, this invention provides a liquid surface mesh modeling method for wave force analysis of a small waterplane area TLP wind turbine platform, comprising the following steps: S1. Based on the column spacing and wave angular frequency of the small waterline TLP fan platform, determine the outer radius of the free liquid surface and the radius of the high-density grid area.

[0037] In this embodiment, the incident wave angular frequency range is 0.25–2.25 rad / s, and the maximum horizontal dimension of the platform is... The radius of the circumcircle formed by all the columns beneath the TLP wind turbine platform is 126 m. Figure 2 The line segment in the diagram is 5 m long.

[0038] The formula for calculating the outer radius of the free surface is:

[0039] in, The outer radius of the free liquid surface, The maximum horizontal dimension of the platform is 126m. The acceleration due to gravity is taken as 9.8 m / s². 2 . The minimum wave angular frequency is 0.25 rad / s. Pi is the mathematical constant, and here it is taken as 3.14.

[0040] The formula for calculating the radius of a high-density grid region is:

[0041] in, The radius of the high-density grid region. Let be the radius of the circumcircle formed by all the columns below the small waterline TLP fan platform, which is the envelope radius at the free liquid surface of the small waterline TLP fan platform. Figure 2 The length of OA in the diagram is 5m. It is the acceleration due to gravity. The maximum wave angular frequency is 2.25 rad / s. The truncation error is set to 0.1 in this embodiment.

[0042] The specific structure of the small waterplane area TLP wind turbine platform used in the embodiments is shown in the attached figure. Figure 2 As shown.

[0043] S2. Within the radius of the high-density grid area, construct a high-density zone. Taking the center of the wind turbine platform as the origin, construct a star-shaped structured grid frame based on the number and layout of the platform columns. Based on the maximum grid length constrained by the maximum wave angular frequency, divide the free liquid surface in the star-shaped structured grid frame into grids. Divide the free liquid surface area between the star-shaped structured grid frame and the radius of the high-density grid area into grids.

[0044] like Figure 3 As shown, in this embodiment, there are six columns under the wind turbine platform, and the six columns are arranged around the center of the wind turbine platform. The steps for establishing the star-shaped structured network framework include: The first step involves establishing parallelogram units of the same size and shape, centered on each of the six columns under the wind turbine platform, within the high-density area.

[0045] The second step is to align one acute vertex of each parallelogram unit with the center of the wind turbine platform, and the length of the side adjacent to the acute vertex coincides with the side length of the adjacent parallelogram unit in the clockwise direction.

[0046] The third step is to construct a star-shaped structured network framework based on the six parallelogram units that have been set up.

[0047] The mesh length in the star-shaped structured network framework is controlled to not exceed the maximum mesh length. The formula for limiting the maximum mesh length is as follows:

[0048] in, For the maximum grid length, It is the acceleration due to gravity. This represents the maximum wave angular frequency.

[0049] Specifically, such as Figure 3 As shown, taking the six pillars at the free surface of the platform as the surrounding objects, six parallelogram units of the same shape and size are constructed in the plane of the free surface. The six parallelogram units are arranged adjacent to each other, so that any parallelogram unit is attached to its adjacent parallelogram unit along one side, and the inner vertices of each of the six parallelogram units converge at the center point of the platform, thus forming a basic grid frame with a hexagonal star structure. The length of each grid in the basic grid frame is controlled to not exceed the maximum grid length of 0.405 m.

[0050] The specific steps for meshing the free surface region between the star-shaped structured network framework and the high-density mesh region radius are as follows: A regular hexagonal structure is constructed based on the six vertices of the outer edge of the star-shaped structured mesh framework. Lines connecting these six vertices and the vertices of the regular hexagonal structure to the center of the circle are projected onto the high-density mesh radius, yielding the mesh nodes for the high-density mesh radius. Based on the partitioned region, the mesh size is constrained within the maximum mesh length, and the meshes are aligned with each other. Finally, the high-density mesh region excluding the star-shaped structured mesh framework is further partitioned.

[0051] S3. Establish a transition zone between the radius of the high-density grid region and the outer boundary of the transition zone, and establish an edge zone between the outer boundary of the transition zone and the outer radius of the free liquid surface. Use the method of dividing concentric rings to mesh the transition zone and the edge zone.

[0052] The meshing steps for the transition and edge regions include: Step 1: Based on the maximum number of grids on the free surface, the total number of grids in the high-density zone, and the number of grids required for each concentric ring, and in conjunction with the set ring number ratio coefficient in the transition zone, calculate the number of concentric rings in the transition zone: =6 in, To take the closest integer, This is the ratio coefficient for the number of rings in the transition zone; in this embodiment, it is set to 0.42. This represents the maximum number of grid cells for the free surface in the SESAM software; in this embodiment, it is set to 20,000. This example uses 4200 grid cells to represent the total number of cells in the high-density region. In this embodiment, the number of grid cells required for each concentric ring is 20. 10 6 = 1200 This represents the number of concentric rings in the transition zone.

[0053] Based on the number of concentric rings in the transition zone, the maximum number of grids on the free surface, the total number of grids in the high-density zone, and the number of grids required for each concentric ring, calculate the number of concentric rings in the edge zone:

[0054] in, This represents the maximum number of grid cells for the free surface in the SESAM software. For all grid cells in the high-density region, The number of grid cells required for each concentric ring. The number of concentric rings in the transition zone. This represents the number of concentric rings in the edge region. It is given based on a specific example; just make sure the grid is aligned.

[0055] The second step is to define the radial stretching factor of the transition region and the edge region. The radial stretching factor of the transition region is in the range of 1.1 to 1.25, and in this embodiment, it is 1.2. The radial stretching factor of the edge region is in the range of 1.2 to 1.35, and in this embodiment, it is 1.25.

[0056] Step 3: Calculate the outer radius of the first concentric ring in the transition zone:

[0057] in, The outer radius of the first concentric ring in the transition zone. The outer radius of the free liquid surface, The radius of the high-density grid region. This is the radial stretching factor for the transition region. The radial stretching factor of the edge region. This represents the number of concentric rings in the transition region, with a value of 6. This represents the number of concentric rings in the edge region, with a value of 7.

[0058] Step 4: Calculate the outer radius of the i-th concentric ring in the transition region:

[0059] in, Let be the outer radius of the i-th concentric ring in the transition region. Let be the radial stretching factor of the transition region of the i-th concentric ring in the transition region. It is the outer radius of the first concentric ring in the transition zone.

[0060] Calculate the outer radius of the j-th concentric ring in the edge region:

[0061] in, Let be the outer radius of the j-th concentric ring in the edge region. The outer radius of the transition zone's outer boundary. Let be the radial stretching factor of the edge region of the j-th concentric ring in the transition region. It is the outer radius of the first concentric ring in the transition zone.

[0062] Step 5: The formula for calculating the outer radius of the transition zone's outer boundary is as follows:

[0063] in, The outer radius of the transition zone's outer boundary.

[0064] Step 6: Based on the outer radius of each concentric ring in the transition zone, the radius of the high-density grid region, and the outer radius of the outer boundary of the transition zone, divide the transition zone into several concentric rings, and perform mesh generation on the transition zone after dividing it into concentric rings. Based on the outer radius of each concentric ring in the edge zone, the outer radius of the outer boundary of the transition zone, and the outer radius of the free liquid surface, divide the edge zone into several concentric rings, and perform mesh generation on the edge zone after dividing it into concentric rings.

[0065] As a preferred embodiment of the present invention, when meshing the transition zone, the intersection points of the radial rays emanating from the center of the platform and distributed at equal angular intervals are found with the concentric rings, and the intersection points are set as meshing nodes so that the nodes of adjacent concentric rings remain aligned in the radial direction; the mesh size gradually increases from the radius of the high-density mesh area to the outer boundary of the transition zone.

[0066] For the gradient mesh in the transition and edge regions, it means that the mesh size in the transition and edge regions increases monotonically in the radial direction, and the mesh size smoothly transitions and continuously increases from the inner boundary to the outer boundary, so as to effectively suppress numerical reflection while controlling the total number of meshes.

[0067] As a preferred embodiment of the present invention, when dividing the edge region into grids, the grid size gradually increases from the outer boundary of the transition zone to the outer radius of the free liquid surface; the grid length of the outermost concentric ring of the edge region is less than or equal to 1 / 15 of the outer radius of the free liquid surface region.

[0068] The distribution of concentric rings is shown in the attached figure. Figure 4 As shown.

[0069] S4. Based on the high-density region, the transition region, and the edge region after meshing, a free surface calculation model for analyzing wave forces is obtained.

[0070] In summary, the meshing strategies for the free liquid surface transition region and edge region in the embodiments are shown in Table 1.

[0071] Table 1

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid surface mesh modeling method for wave force analysis of a small waterplane area TLP wind turbine platform, characterized in that, Includes the following steps: Based on the column spacing and wave angular frequency of the small waterplane surface TLP fan platform, the outer radius of the free liquid surface and the radius of the high-density grid region are determined. The formula for calculating the outer radius of the free liquid surface is as follows: in, The outer radius of the free liquid surface, The maximum horizontal length of the platform. It is the acceleration due to gravity. The minimum wave angular frequency, Let pi be the mathematical constant, and the formula for calculating the radius of the high-density grid region is: in, The radius of the high-density grid region. Let be the radius of the circumcircle formed by all the columns beneath the TLP wind turbine platform. It is the acceleration due to gravity. The maximum wave angular frequency, This is the truncation error; Within the radius of the high-density grid area, a high-density zone is constructed. Taking the center of the wind turbine platform as the origin, a star-shaped structured grid frame is constructed based on the number and layout of the platform columns. According to the maximum grid length constrained by the maximum wave angular frequency, the free liquid surface in the star-shaped structured grid frame is divided into grids. The free liquid surface area between the star-shaped structured grid frame and the radius of the high-density grid area is also divided into grids. A transition zone is established between the radius of the high-density grid region and the outer boundary of the transition zone. An edge zone is established between the outer boundary of the transition zone and the outer radius of the free liquid surface. The transition zone and the edge zone are meshed using a method of dividing concentric rings. Based on the high-density region, transition region, and edge region after meshing, a free surface calculation model for analyzing wave forces is obtained.

2. The liquid surface mesh modeling method for wave force analysis of a small waterplane area TLP wind turbine platform according to claim 1, characterized in that, The steps for establishing the star-shaped structured network framework include: There are six columns under the wind turbine platform. In the high-density area, parallelogram units of the same size and shape are built with each column under the wind turbine platform as the center. One acute vertex of each parallelogram unit coincides with the center of the wind turbine platform, and the length of the side adjacent to the acute vertex coincides with the side length of the adjacent parallelogram unit in the clockwise direction. Based on the six parallelogram units configured, a star-shaped structured network framework is constructed.

3. The liquid surface mesh modeling method for wave force analysis of a small waterplane area TLP wind turbine platform according to claim 2, characterized in that, The grid length in the star-shaped structured network framework is controlled to not exceed the maximum grid length, and the formula for limiting the maximum grid length is as follows: in, For the maximum grid length, It is the acceleration due to gravity. This represents the maximum wave angular frequency.

4. The liquid surface mesh modeling method for wave force analysis of a small waterplane area TLP wind turbine platform according to claim 1, characterized in that, The meshing steps for the transition and edge regions include: Based on the maximum number of grids on the free surface, the total number of grids in the high-density region, and the number of grids required for each concentric ring, combined with the set ring number ratio coefficient in the transition region, the number of concentric rings in the transition region is calculated: in, To take the closest integer, This is the ratio coefficient of the number of rings in the transition zone. This represents the maximum number of grid cells for the free surface in the SESAM software. For all grid cells in the high-density region, The number of grid cells required for each concentric ring. The number of concentric rings in the transition zone; Based on the number of concentric rings in the transition zone, the maximum number of grids on the free surface, the total number of grids in the high-density zone, and the number of grids required for each concentric ring, calculate the number of concentric rings in the edge zone: in, The number of concentric rings in the edge region; Define the radial stretching factor of the transition region, wherein the value of the radial stretching factor of the transition region ranges from 1.1 to 1.25; Define a radial stretching factor for the edge region, wherein the value of the radial stretching factor for the edge region ranges from 1.2 to 1.35; Calculate the outer radius of the first concentric ring in the transition region: in, The radius of the outer edge of the first concentric ring in the transition zone. The outer radius of the free liquid surface, The radius of the high-density grid region. This is the radial stretching factor for the transition region. The radial stretching factor of the edge region. The number of concentric rings in the transition zone. The number of concentric rings in the edge region; Calculate the outer radius of the i-th concentric ring in the transition region: in, Let be the outer radius of the i-th concentric ring in the transition region. Let be the radial stretching factor of the transition region of the i-th concentric ring in the transition region. The radius of the outer edge of the first concentric ring in the transition zone; Calculate the outer radius of the j-th concentric ring in the edge region: in, Let be the outer radius of the j-th concentric ring in the edge region. The outer radius of the transition zone's outer boundary. Let be the radial stretching factor of the edge region of the j-th concentric ring in the transition region. The radius of the outer edge of the first concentric ring in the transition zone; The formula for calculating the outer radius of the outer boundary of the transition zone is: in, The outer radius of the transition zone's outer boundary; Based on the outer radius of each concentric ring in the transition zone, the radius of the high-density grid region, and the outer radius of the outer boundary of the transition zone, the transition zone is divided into several concentric rings, and the transition zone after dividing into concentric rings is meshed. Based on the outer edge radius of each concentric ring in the edge region, the outer edge radius of the transition region, and the outer radius of the free liquid surface, the edge region is divided into several concentric rings, and the edge region after dividing into concentric rings is meshed.

5. The liquid surface mesh modeling method for wave force analysis of a small waterplane surface TLP wind turbine platform according to claim 4, characterized in that, When meshing the transition zone, along the radial rays emanating from the center of the platform and distributed at equal angular intervals, find the intersection points of the radial rays and the concentric rings, and set the intersection points as meshing nodes so that the nodes of adjacent concentric rings remain aligned in the radial direction. The grid size gradually increases from the radius of the high-density grid region to the outer boundary of the transition zone.

6. The liquid surface mesh modeling method for wave force analysis of a small waterplane surface TLP wind turbine platform according to claim 4, characterized in that, When meshing the edge region, the mesh size gradually increases from the outer boundary of the transition zone to the outer radius of the free liquid surface; The grid length of the outermost concentric ring in the edge region is less than or equal to 1 / 15 of the outer radius of the free liquid surface region.

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