Full-automatic non-structural hybrid grid generation method for ship fluid computational domain

Abstract

The invention discloses a ship fluid computational domain full-automatic non-structural hybrid grid generation method, which comprises the following steps: acquiring a ship geometric model, adding a computational domain bounding box, and generating an initial discrete geometric model consisting of triangular surface grids; acquiring user input control parameters, and generating a size field in combination with the initial discrete geometric model; embedding a symmetric plane and a horizontal plane according to the initial discrete geometric model, generating an initial triangular surface grid with consistent boundaries, and performing re-gridding under the control of a size field to generate a model boundary surface grid; according to a horizontal plane, dividing the boundary surface grid into an upper surface grid and a lower surface grid, and respectively generating an upper boundary layer grid and a lower boundary layer grid which are composed of anisotropic triangular prism units and pyramid units; on this basis, surface grids of the boundary of the computational domain are regenerated at the boundary of the bounding box, tetrahedral grid units are generated under the control of the size field, and therefore the ship fluid computational domain full-automatic non-structural hybrid grid is formed through merging.

Description

Technical Field

[0001] This invention relates to the field of ship fluid analysis mesh generation technology, and in particular to a fully automatic unstructured hybrid mesh generation method for ship fluid computational domains. Background Technology

[0002] In the modern shipbuilding industry, hull design directly determines a ship's sailing performance, fuel efficiency, and safety stability. Ship fluid analysis, as a core supporting tool in the conceptual and technical design phases, permeates the entire process from initial scheme selection to final performance optimization. Whether assessing a ship's resistance and propulsion efficiency in calm water and waves, or simulating complex phenomena such as cabin flow fields and propeller cavitation, the accuracy of fluid analysis directly impacts the scientific validity of design decisions. Within the entire fluid analysis process, mesh generation, as the core of the preprocessing stage, transcends the scope of "basic preparation work" and can be considered the "cornerstone" of the success or failure of numerical simulation. The core role of mesh generation lies in two key dimensions: First, mesh quality directly determines the accuracy, efficiency, and reliability of subsequent calculations. Ship flow fields involve complex flow phenomena such as boundary layers, separated flows, and vortices. If the mesh has problems such as excessively high distortion, uneven node distribution, or insufficient boundary layer mesh refinement, it will not only lead to significant deviations between the calculated results and actual physical phenomena—for example, the error in ship resistance calculation may exceed 10%—but may also cause solver iterative divergence, directly causing the entire numerical simulation to fail. Conversely, high-quality structured or unstructured meshes can reduce computational resource consumption while ensuring computational accuracy, shortening the simulation cycle from weeks to days. Second, the current mesh generation process for complex ships (such as LNG carriers and high-performance military vessels) still heavily relies on the experience of operators and is difficult to automate completely. From the preprocessing of complex geometric models (such as repairing gaps and overlapping surfaces in CAD models), to planning the mesh topology based on flow field characteristics, and then to adjusting the stretching ratio and refinement coefficient of the boundary layer mesh, each step requires manual intervention from senior engineers. According to industry statistics, this type of manual operation accounts for 60%-80% of the workload in the entire numerical simulation process. It not only prolongs the ship design cycle, but also leads to insufficient grid quality stability due to differences in personnel experience, which restricts the improvement of design efficiency. Looking back at the development of mesh generation technology, from the early manual point-by-point mesh generation to the mid-term semi-automatic mesh generation, and now to the exploration of intelligent mesh generation, "automation" has always been a core research topic in the industry. As ship design develops towards "short cycle, high precision, and multi-scheme comparison," the traditional manual mesh generation mode can no longer meet the needs. Achieving fully automatic conversion from geometric models to high-quality meshes has become the key to breaking through the bottleneck of design efficiency. However, domestically developed CAE software still has significant problems. For example, when dealing with complex geometric structures such as LNG ship tanks and high-performance ship appendages, it often faces issues such as low geometric repair efficiency and difficulty in controlling mesh distortion rate; in terms of automation, most software still requires a large amount of manual intervention and is difficult to achieve the "one-click generation" standard. Summary of the Invention

[0003] Based on this, the present invention proposes a fully automatic unstructured hybrid mesh generation method for ship fluid computation domain to solve the problems existing in the prior art.

[0004] According to a first aspect of the embodiments of this application, a fully automatic unstructured hybrid mesh generation method for ship fluid computational domains is provided, comprising: S1: Obtain the ship's geometric model, and based on the ship's geometric model, add a computational domain bounding box to generate an initial discrete geometric model composed of triangular surface meshes; S2: Obtain user-input control parameters, and generate a size field based on the initial discrete geometric model and user-input control parameters; S3: Based on the initial discrete geometric model, embed the symmetry plane and the horizontal plane, and generate an initial triangular surface mesh with consistent boundaries; S4: Based on the initial triangular surface mesh, remesh is performed under the control of the size field to generate the model boundary surface mesh; S5: Based on the horizontal plane, the boundary surface mesh is divided into upper and lower surface meshes; S6: Generate boundary layer meshes for the upper and lower surface meshes, respectively, consisting of anisotropic triangular prism elements and pyramid elements. S7: Based on the boundaries of the upper and lower boundary layer meshes, regenerate the surface mesh of the computational domain boundary at the boundary of the bounding box, and generate tetrahedral mesh elements under the control of the size field. S8: Based on the boundary layer mesh and tetrahedral mesh elements of the upper and lower parts, merge all volume mesh elements into a fully automatic unstructured hybrid mesh for the ship fluid computation domain.

[0005] Further, step S1 includes: S11: Obtain the ship's geometric model; S12: Identify the model size and feature length of the ship geometry model, and add a computational domain bounding box for the ship geometry model based on the model size and feature length; S13: Based on the ship geometry model and the computational domain bounding box, generate an initial discrete geometry model consisting of triangular surface meshes.

[0006] Further, step S2 includes: S21: Obtain user input control parameters, and generate a size field based on the geometric features according to the geometric features of the initial discrete geometric model and the user input control parameters; S22: Based on user-input control parameters, use mesh source technology to control mesh size.

[0007] Further, step S3 includes: S31: Generate an initial triangular planar mesh at the symmetry plane of the initial discrete geometric model, perform Boolean intersection, embed it into the symmetry plane, and take half of the embedded mesh as the semi-model surface mesh; S32: Based on the semi-model surface mesh, generate an initial triangular planar mesh at the horizontal plane of the initial discrete geometric model, perform Boolean intersection, embed it into the horizontal plane, and obtain an initial triangular surface mesh with consistent boundaries and a horizontal plane.

[0008] Further, step S4 includes: S41: Based on the initial triangular surface mesh, under the control of the size field, perform edge segmentation, edge merging, edge flipping, and point optimization to update the current model boundary surface mesh; Among them, edge splitting refers to inserting a new vertex at the midpoint or other specific position of an edge to split an edge into two, thereby refining the mesh; edge merging is to merge two vertices and remove an edge to simplify the mesh; edge flipping changes the topology of the mesh by reconnecting the two diagonal vertices of an edge, that is, for a pair of triangles sharing an edge, if the minimum interior angle of the new triangle formed after the edge swap operation is larger, then the edge swap operation is performed; point optimization operation is used to improve the uniformity of the mesh, specifically, for a mesh point, the triangular cell formed with all the mesh points around it needs to have its midpoint moved to the centroid of all the surrounding points; S42: Check whether the edge length of all meshes on the current model boundary surface mesh conforms to the size value of the size field at its location. If there are non-conforming mesh edges, return to step S41 until the edge length of all meshes conforms to the size value of the size field at its location.

[0009] Further, step S6 includes: S61: Based on the user-input control parameters, using the triangular mesh of the hull surface and the horizontal plane as the initial growth surface, calculate the normal and travel distance of each mesh point, use the leading edge layering method to generate a layer of triangular prism elements and use the top layer mesh as the new growth surface; S62: Repeat step S61 until the number of triangular prism unit layers reaches the target, and generate transition pyramid units. If any of the following conditions are met, the number of triangular prism unit layers is determined to be up to the target: (1) The current layer reaches the upper limit of the total number of layers set by the user; (2) The aspect ratio of the current unit reaches the ratio set by the user; (3) The boundary layer mesh of the new layer will intersect.

[0010] Further, step S7 includes: S71: Extract the top boundary layer of the boundary layer mesh and the top layer of the original model boundary surface mesh, and use them as the two boundary surface meshes of the tetrahedral mesh; S72: Extract the boundary lines of the two boundary surface meshes and generate line meshes at the four opposite corners as the boundary line meshes of the four side boundaries of the tetrahedral mesh. S73: Using the leading edge propagation method, generate the surface mesh of the four lateral boundaries of the tetrahedral mesh based on the above boundary line mesh; S74: Based on the boundary surface mesh, tetrahedral mesh elements are generated inside the boundary mesh using the Delaunay triangulation method under the control of the size field. When inserting an internal point, if the side length of the element generated at the insertion point does not meet the size field requirements, the insertion of the internal point is abandoned.

[0011] According to a second aspect of the embodiments of this application, a computer program product is provided, including a computer program / instructions that, when executed by a processor, implement the method described in the first aspect.

[0012] According to a third aspect of the embodiments of this application, an electronic device is provided, comprising: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors perform the method as described in the first aspect.

[0013] According to a fourth aspect of the embodiments of this application, a computer-readable storage medium is provided that stores computer instructions thereon, which, when executed by a processor, implement the steps of the method as described in the first aspect.

[0014] The technical solutions provided by the embodiments of this application may include the following beneficial effects: This invention improves the accuracy and efficiency of model processing by performing model processing on discrete geometric models. It proposes using a size field control based on the combined effects of geometric features and mesh source technology to generate surface and volume meshes, automatically adjusting mesh size distribution and transitions to generate high-quality, smoothly transitioned meshes. It also proposes splitting the model into two parts using a horizontal plane as a boundary, and generating volume meshes using the same method, thus improving mesh generation efficiency. Planar embedding technology is used to solve the problem of mesh consistency errors at the horizontal plane. Simultaneously, geometrically adaptive size field control technology and mesh source technology are used to perform fine-grained mesh size control in specified areas, optimizing mesh quality in complex regions. Furthermore, this invention only requires the user to preset some parameters and input the ship's geometric model at the beginning, enabling a fully automated mesh generation process, achieving a "one-click generation" standard.

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] Figure 1 This is a flowchart illustrating a fully automated unstructured hybrid mesh generation method for a ship fluid computational domain, according to an exemplary embodiment.

[0018] Figure 2 This is a geometric model diagram of the KCS standard model shown according to an exemplary embodiment.

[0019] Figure 3 This is a schematic diagram of a geometric model with an added bounding box, according to an exemplary embodiment.

[0020] Figure 4 This is a schematic diagram of an initial discrete geometric model consisting of a triangular surface mesh, according to an exemplary embodiment.

[0021] Figure 5 This is a schematic diagram of the curvature feature adaptive unit size calculation.

[0022] Figure 6 This is a schematic diagram illustrating the process of embedding a symmetric plane and taking a half-mode through Boolean operations according to an exemplary embodiment.

[0023] Figure 7 This is a schematic diagram of a semi-mold initial triangular surface mesh with consistent boundaries and a horizontal plane, according to an exemplary embodiment.

[0024] Figure 8This is a schematic diagram illustrating the four remeshing operations in S41 according to an exemplary embodiment.

[0025] Figure 9 This is a schematic diagram illustrating, according to an exemplary embodiment, the division of a boundary surface mesh into upper and lower parts based on a horizontal plane.

[0026] Figure 10 This is a schematic diagram of a boundary layer mesh according to an exemplary embodiment.

[0027] Figure 11 This is a schematic diagram illustrating the extraction of boundary line meshes and the generation of line meshes at the four diagonal points according to an exemplary embodiment.

[0028] Figure 12 This is a cross-sectional view of a tetrahedral mesh boundary surface mesh according to an exemplary embodiment.

[0029] Figure 13 This is a schematic diagram illustrating the generation of a high-quality tetrahedral mesh outside a boundary layer mesh according to an exemplary embodiment.

[0030] Figure 14 This is a schematic diagram of a hybrid mesh according to an exemplary embodiment.

[0031] Figure 15 This is a block diagram illustrating a fully automated unstructured hybrid mesh generation device for a ship fluid computational domain, according to an exemplary embodiment.

[0032] Figure 16 This is a schematic diagram of an electronic device according to an exemplary embodiment. Detailed Implementation

[0033] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0034] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0035] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0036] Figure 1 This is a flowchart illustrating a fully automated unstructured hybrid mesh generation method for ship fluid computational domains, according to an exemplary embodiment. Figure 1 As shown, the method includes the following steps: S1: Obtain the ship's geometric model, and based on the ship's geometric model, add a computational domain bounding box to generate an initial discrete geometric model composed of triangular surface meshes.

[0037] S11: Obtain the ship's geometric model; This application utilizes the Open CASCADE geometry engine to read ship geometry model data, taking the KCS standard model as an example. Figure 2 As shown, its geometric model data includes geometric information (point coordinates and line and surface parametric equations) and topological information (clarifying the hierarchical relationship between volume, surface, line and point: a volume is composed of surfaces, a surface is composed of lines, and a line is composed of two endpoints).

[0038] S12: Identify the model size and feature length of the ship geometry model, and add a computational domain bounding box for the ship geometry model based on the model size and feature length; Based on conventional ship fluid analysis calculations, the system automatically adjusts the coordinates in situ and automatically identifies the model dimensions and feature lengths of the ship's geometric model. Users can then define the computational domain bounding box, or, based on this, add an outer bounding box using the Open CASCADE geometry engine. Figure 3 As shown.

[0039] S13: Based on the ship geometry model and the computational domain bounding box, generate an initial discrete geometry model consisting of triangular surface meshes.

[0040] Based on the CAD geometric model with added bounding boxes, the STL conversion algorithm of the geometry engine Open CASCADE is used to convert it into a form-preserving discrete geometric model composed of triangular surface meshes, such as... Figure 4 As shown.

[0041] S2: Obtain user-input control parameters, and generate a size field based on the initial discrete geometric model and user-input control parameters.

[0042] S21: Obtain user-input control parameters, and generate a size field based on the geometric features according to the geometric features of the initial discrete geometric model and the user-input control parameters.

[0043] The grid size field h(S) is a spatial scalar field defined on the region to be discretized, and its function value represents the proposed grid cell density distribution at any point S in space. Ideally, this function should follow an adaptive principle: a high-density grid should be configured in regions with significant geometric features (such as regions with abrupt curvature changes), while a sparse grid layout should be used in regions with gentler features. For the ship fluid domain model, curvature is mainly considered as a geometric feature. (Known sampling points...) radius of curvature ,in Its curvature value, such as Figure 4 As shown, construct a line connecting the center of a circle and the sampling point. Coinciding with the normal vector of the sampling point, the radius is... Equal circles. Cell size at point S and the generated mesh edges. Zhang Jiao The following relationship exists: Input control parameters for the user. If higher mesh shape preservation is required, i.e., mesh edges... It should fit the curved surface as closely as possible. It should be as small as possible, but the corresponding mesh size will also increase.

[0044] S22: Based on user-input control parameters, mesh size control is performed using mesh source technology; A mesh source can be defined on a point, a line, a surface, or a volume, referred to as a point source, line source, surface source, and volume source, respectively. The gradual control of mesh size is achieved through a distance function: the mesh size is small near the source and gradually increases with distance from the source. The influence of the source on the size value of a point in space can be represented in polynomial form, retaining only the first-order terms, as shown below: h = h0 + a0*d Where h represents the size of any point in space, h0 represents the intensity of the point projected onto the source; for line sources, surface sources, and volume sources, the intensity of the projected point can be obtained by linear interpolation of the boundary points. d is the distance between the query point and the projected point, and a0 is a user-defined transition factor.

[0045] It should be noted that step S22 can be a further adjustment of the size field generated in step S21, or it can be a new size field generated based on user-input control parameters. If it is the former, then the subsequent phrase "under the control of the size field" means under the control of the size field adjusted in step S22; if it is the latter, then the subsequent phrase "under the control of the size field" means under the control of the two size fields generated in steps S21 and S22, selecting the relatively smaller size.

[0046] S3: Based on the initial discrete geometric model, embed the symmetry plane and the horizontal plane, and generate an initial triangular surface mesh with consistent boundaries.

[0047] S31: Generate an initial triangular planar mesh at the symmetry plane of the initial discrete geometric model, perform Boolean intersection, embed it into the symmetry plane, and take half of the embedded mesh as the semi-model surface mesh; A planar triangular mesh is generated in the horizontal plane. In this embodiment, it is generated by diagonal subdivision. Figure 6 As shown, Boolean operations are performed using a surface mesh generation method based on Delaunay tetrahedralization. The symmetry plane is embedded into the initial mesh, and the new mesh is divided into two sides according to the symmetry plane. Based on the topological relationship between the new mesh element and the symmetry plane, the mesh on one side is deleted to obtain the surface mesh of the half-model. This mesh will be used as the input for subsequent processes, reducing the amount of mesh generation by half.

[0048] S32: Based on the semi-mold surface mesh, generate an initial triangular planar mesh at the horizontal plane of the initial discrete geometric model, perform Boolean intersection, embed it into the horizontal plane, and obtain an initial triangular surface mesh with consistent boundaries and a horizontal plane. The embedding method for the horizontal plane is the same as that for the symmetric plane, thus obtaining an initial triangular surface mesh with a consistent boundary and a horizontal plane, such as... Figure 7 As shown.

[0049] S4: Based on the initial triangular surface mesh, remesh is performed under the control of the size field to generate the model boundary surface mesh.

[0050] S41: Based on the initial triangular surface mesh, perform edge segmentation, edge merging, edge flipping, and point optimization under the control of the size field to update the current model boundary surface mesh.

[0051] The initial triangular surface mesh is used as the initial mesh, and an iterative remeshing operation is performed on it. Each round of remeshing includes four basic operations: edge splitting, edge merging, edge flipping, and point optimization. Figure 8As shown, specifically, edge splitting refers to inserting a new vertex at the midpoint or other specific position of an edge, dividing one edge into two, thereby refining the mesh. This is especially useful when higher resolution detail is required in certain areas of the model. Specifically, for a mesh edge, if its length is greater than 5 / 3 of the size field control value of that area, an edge splitting operation is performed. Edge merging combines two vertices and removes an edge, thereby reducing the number of vertices and edges in the mesh to simplify it. Specifically, for a mesh edge, if its length is less than 2 / 3 of the size field control value of that area, an edge merging operation is performed. Edge flipping is an operation that optimizes mesh quality by reconnecting the two diagonal vertices of an edge, changing the topology of the mesh. Specifically, for a pair of triangles sharing an edge, if the minimum interior angle of the new triangle formed after an edge swap operation is larger, an edge swap operation is performed. Point optimization involves adjusting the position of vertices to improve mesh uniformity and reduce local energy concentration, thereby optimizing the overall quality and functionality of the model. Specifically, for a mesh point and the triangular unit formed with all surrounding mesh points, the midpoint needs to be moved to the centroid of all surrounding points.

[0052] S42: Check whether the edge length of all meshes on the current model boundary surface mesh conforms to the size value of the size field at its location. If there are non-conforming mesh edges, return to step S41 until the edge length of all meshes conforms to the size value of the size field at its location.

[0053] During each local remeshing operation, the mesh edge length at the corresponding location is checked. If the mesh edge length in that region does not meet the size field constraints, it means that the mesh has not yet met the requirements. Remeshing needs to continue until the global mesh edge length meets the size field constraints.

[0054] S5: Based on the horizontal plane, the boundary surface mesh is split into upper and lower surface meshes.

[0055] like Figure 9 As shown, based on the topological relationship between the current model boundary surface mesh cells and the horizontal plane, the boundary surface mesh is split into upper and lower surface meshes. The meshes of these two parts are completely identical in the horizontal plane region, which is why the subsequent volume meshes can be directly merged.

[0056] S6: For the upper and lower surface meshes, generate upper and lower boundary layer meshes composed of anisotropic triangular prism elements and pyramid elements respectively.

[0057] S61: Based on the user-input control parameters, using the triangular mesh of the hull surface and the horizontal plane as the initial growth surface, calculate the normal and travel distance of each mesh point, use the leading edge layering method to generate a layer of triangular prism elements and use the top layer mesh as the new growth surface.

[0058] The normal vector of each grid point is the average of the normal vectors of the nearby triangular facets. Then, the normal vector of the grid point is optimized using the Laplacian smoothing method. The travel distance calculated for each grid point is: here, This represents the current distance traveled. α The growth rate of the boundary layer, n This is the current floor number. h 0 This refers to the height of the first floor. α and h 0 Input control parameters for the user.

[0059] S62: Repeat step S61 until the number of triangular prism unit layers reaches the target, generating transition pyramid units.

[0060] There are three main criteria for meeting the standard for the number of layers in a triangular prism element: (1) the current number of layers reaches the upper limit of the total number of layers set by the user; (2) the aspect ratio of the current element reaches the ratio set by the user; and (3) the boundary layer mesh of the new layer will intersect. If any one of the above conditions is met, the number of layers in the triangular prism element is considered to be up to standard.

[0061] When all layers of the triangular prism unit stop growing, transitional pyramid units are generated in areas with inconsistent layer heights to cover the exposed quadrilateral units, ultimately resulting in the following: Figure 10 The boundary layer mesh shown is only shown in the image for illustration purposes, as the upper and lower meshes are generated using the same method.

[0062] S7: Based on the boundaries of the upper and lower boundary layer meshes, the surface meshes of the computational domain boundary are regenerated at the boundary of the bounding box, and tetrahedral mesh elements are generated under the control of the size field.

[0063] In the far field region, a tetrahedral mesh needs to be generated. The boundary of this region is a box-like area consisting of six faces. Four of the sides are part of the four sides of the original model's bounding box, and the top and bottom faces are the top layer of the boundary layer mesh and the top layer of the original model's boundary surface mesh, respectively.

[0064] Since the generation of the boundary layer mesh disrupts the original mesh on the symmetry plane and the bounding box, the surface meshes on the four sides need to be regenerated, and then a tetrahedral mesh is generated from this boundary.

[0065] S71: Extract the top boundary layer of the boundary layer mesh and the top layer of the original model boundary surface mesh as two boundary surface meshes of the tetrahedral mesh.

[0066] Since the meshes on the top and bottom surfaces are the top layers of the boundary layer mesh and the top layers of the original model boundary surface mesh, respectively, they do not need to be regenerated and can be extracted directly.

[0067] S72: Extract the boundary lines of the two boundary surface meshes and generate line meshes at the four opposite corners as the boundary line meshes of the four side boundaries of the tetrahedral mesh.

[0068] The boundaries of the surface meshes on all four sides are each defined by four line meshes, two each in the horizontal and vertical directions. The horizontal line meshes are the same as the boundary line meshes extracted in the previous step, and can be extracted directly.

[0069] There are a total of four vertical grid lines, which can be generated directly. The grid density should be higher near the boundary layer to ensure a natural grid transition, such as... Figure 11 As shown.

[0070] S73: Using the leading edge method, generate the surface mesh of the four lateral boundaries of the tetrahedral mesh based on the above boundary line mesh.

[0071] Figure 12 The diagram shows a cross-sectional view of the generated tetrahedral mesh boundary surface after the boundary line mesh is determined.

[0072] S74: Based on the boundary surface mesh, tetrahedral mesh elements are generated inside the boundary mesh using the Delaunay triangulation method under the control of the size field.

[0073] Based on the boundary surface mesh, tetrahedral mesh elements are generated inside the boundary mesh using the Delaunay triangulation method. When inserting internal points, if the edge length of the generated element does not meet the size field requirements, the insertion of the internal point must be abandoned. This allows for the generation of high-quality tetrahedral meshes outside the boundary layer mesh, such as... Figure 13 As shown.

[0074] S8: Based on the boundary layer mesh and tetrahedral mesh elements of the upper and lower parts, merge all volume mesh elements into a fully automatic unstructured hybrid mesh for the ship fluid computation domain.

[0075] Specifically, hexahedral elements, pyramidal elements, tetrahedral elements, and triangular prism elements are merged to generate a hybrid mesh, such as... Figure 14 As shown, the total number of elements in the example is 3,654,075, of which there are 1,346,473 tetrahedral elements, 2,267,423 triangular prism elements, and 40,179 pyramid elements.

[0076] Corresponding to the aforementioned embodiments of the fully automatic unstructured hybrid mesh generation method for ship fluid computational domains, this application also provides embodiments of a fully automatic unstructured hybrid mesh generation device for ship fluid computational domains.

[0077] Figure 15 This is a block diagram of a fully automated unstructured hybrid mesh generation device for ship fluid computational domains, according to an exemplary embodiment. (Refer to...) Figure 15 The device may include: The initial model generation module 21 is used to obtain the ship's geometric model and, based on the ship's geometric model, add a computational domain bounding box to generate an initial discrete geometric model composed of triangular surface meshes. The size field generation module 22 is used to acquire user input control parameters and generate a size field based on the initial discrete geometric model and the user input control parameters. The initial surface mesh generation module 23 is used to embed the symmetry plane and the horizontal plane according to the initial discrete geometric model, and generate an initial triangular surface mesh with consistent boundaries; The remeshing module 24 is used to remesh the initial triangular surface mesh under the control of the size field to generate the model boundary surface mesh. The mesh splitting module 25 is used to split the boundary surface mesh into upper and lower surface meshes according to the horizontal plane. The surface mesh generation module 26 is used to generate surface meshes composed of anisotropic triangular prism units and pyramid units for the upper and lower surface meshes, respectively. The volume mesh generation module 27 is used to regenerate the surface mesh of the computational domain boundary at the boundary of the bounding box according to the boundaries of the upper and lower boundary layer meshes, and generate tetrahedral mesh elements under the control of the size field. The merging module 28 is used to merge all volume grid cells into a fully automatic unstructured hybrid grid for the ship fluid computation domain based on the boundary layer grid and tetrahedral grid cells of the upper and lower parts.

[0078] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0079] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0080] Accordingly, this application also provides a computer program product, including a computer program / instruction that, when executed by a processor, implements the fully automatic unstructured hybrid mesh generation method for ship fluid computational domains as described above.

[0081] Accordingly, this application also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; and, when the one or more programs are executed by the one or more processors, causing the one or more processors to implement the fully automated unstructured hybrid mesh generation method for the ship fluid computational domain as described above. Figure 16 The diagram shown is a hardware structure diagram of any device with data processing capabilities, which is the site of a fully automatic unstructured hybrid mesh generation device for ship fluid computational domains provided in an embodiment of the present invention. (Except for...) Figure 16 In addition to the processor, memory, and network interface shown, any data processing device in the embodiment may also include other hardware depending on the actual function of the data processing device, which will not be described in detail here.

[0082] Accordingly, this application also provides a computer-readable storage medium storing computer instructions, which, when executed by a processor, implement the fully automated unstructured hybrid mesh generation method for the ship fluid computational domain as described above. The computer-readable storage medium can be an internal storage unit of any data processing device as described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units of any data processing device and external storage devices. The computer-readable storage medium is used to store the computer program and other programs and data required by the data processing device, and can also be used to temporarily store data that has been output or will be output.

[0083] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A method for full automatic unstructured hybrid mesh generation for ship fluid computation domain, characterized in that, The method comprises the following steps: S1: obtaining a ship geometric model, and adding a calculation domain bounding box according to the ship geometric model to generate an initial discrete geometric model composed of triangular surface meshes; S2: obtaining user input control parameters, and generating a size field according to the initial discrete geometric model and the user input control parameters; S3: embedding a symmetry plane and a horizontal plane according to the initial discrete geometric model, and generating an initial triangular surface mesh with consistent boundaries; S4: re-meshing the initial triangular surface mesh under the control of the size field to generate a model boundary surface mesh; S5: splitting the boundary surface mesh into upper and lower part surface meshes according to the horizontal plane; S6: generating upper and lower part boundary layer meshes composed of anisotropic triangular prismatic elements and pyramid elements from the upper and lower part surface meshes, respectively; S7: generating a tetrahedral mesh element under the control of the size field according to the boundaries of the upper and lower part boundary layer meshes, and re-generating a surface mesh of a calculation domain boundary at the bounding box boundary; S8: combining all volume mesh elements into a full-automatic non-structural hybrid mesh of a ship fluid calculation domain according to the upper and lower part boundary layer meshes and the tetrahedral mesh element.

2. The method of claim 1, wherein, Step S1 comprises: S11: obtaining a ship geometric model; S12: identifying a model size and a characteristic length of the ship geometric model, and adding a calculation domain bounding box of the ship geometric model according to the model size and the characteristic length; S13: generating an initial discrete geometric model composed of triangular surface meshes according to the ship geometric model and the calculation domain bounding box.

3. The method of claim 1, wherein, Step S2 comprises: S21: obtaining user input control parameters, and generating a size field based on geometric features according to geometric features of the initial discrete geometric model and the user input control parameters; S22: using a grid source technique to control mesh size according to the user input control parameters.

4. The method of claim 1, wherein, Step S3 comprises: S31: generating an initial triangular plane mesh at a symmetry plane of the initial discrete geometric model, performing Boolean intersection, embedding the symmetry plane, and taking half of the embedded mesh as a half-model surface mesh; S32: generating an initial triangular plane mesh at a horizontal plane of the initial discrete geometric model according to the half-model surface mesh, performing Boolean intersection, embedding the horizontal plane, and obtaining an initial triangular surface mesh with consistent boundaries and a horizontal plane.

5. The method of claim 1, wherein, Step S4 comprises: S41: performing edge splitting, edge merging, edge flipping and point optimization according to the initial triangular surface mesh under the control of the size field, and updating a current model boundary surface mesh; Among them, edge segmentation refers to inserting a new vertex at the midpoint or other specific positions of the edge, dividing an edge into two to refine the mesh; edge merging is to merge two vertices and remove an edge to simplify the mesh; edge flipping changes the topology of the mesh by reconnecting the two diagonal vertices of the edge, that is, for a pair of triangles sharing an edge, if the minimum internal angle of the new triangle formed after the edge exchange operation is larger, the edge exchange operation is performed; the point optimization operation is used to improve the uniformity of the mesh, specifically, for a mesh point, the intermediate point needs to be moved to the center of gravity of all surrounding points to form a triangular element with all surrounding points. S42: Check whether all mesh edge lengths of the current model boundary surface mesh conform to the size values of the size field at their positions. If there is a mesh edge that does not conform, return to step S41 until all mesh edge lengths conform to the size values of the size field at their positions.

6. The method of claim 1, wherein, Step S6 includes: S61: According to the user input control parameters, taking the triangular face mesh of the hull surface and the horizontal plane as the initial growth surface, calculating the normal vector and marching distance of each mesh point, and using the front layer advancing method to generate a layer of triangular prism elements and take the top surface mesh as the new growth surface; S62: Repeat step S61 until the number of layers of triangular prism elements meets the standard, and generate the transition pyramid elements, wherein if any of the following conditions is met, it is determined that the number of layers of triangular prism elements meets the standard: (1) the current number of layers reaches the upper limit of the total number of layers set by the user; (2) the aspect ratio of the current element reaches the ratio set by the user; (3) the new layer of the boundary layer mesh will intersect.

7. The method of claim 1, wherein, Step S7 includes: S71: Extract the boundary top layer of the boundary layer mesh and the top layer of the original model boundary surface mesh as two boundary surface meshes of the tetrahedral mesh; S72: Extract the boundary lines of the two boundary surface meshes, and generate line meshes at four corner points as boundary line meshes of the four side boundaries of the tetrahedral mesh; S73: Using the front advancing method, generate surface meshes of the four side boundaries of the tetrahedral mesh according to the above boundary line meshes; S74: According to the boundary surface mesh, generate tetrahedral mesh elements inside the boundary mesh using the Delaunay triangulation method under the control of the size field, wherein when inserting an internal point, if the element length generated by the inserted point does not meet the size field requirement, the insertion of the internal point is abandoned.

8. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instructions are executed by the processor to implement the method of any one of claims 1-7.

9. An electronic device, comprising: Comprise: One or more processors; Memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method of any one of claims 1-7.

10. A computer readable storage medium having stored thereon computer instructions, wherein, The instructions are executed by the processor to implement the steps of the method of any one of claims 1-7. The instructions are executed by the processor to implement the steps of the method of any one of claims 1-7.

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