Jianfei Liu

Peking University | PKU

Purpose During the industrial design process, a product is usually modified and analyzed repeatedly until reaching the final design. Modifying the model and regenerating a mesh for every update during this process is very time consuming. To improve efficiency, it is necessary to circumvent the computer-aided design modeling stage when possible and...

In this paper, we present a solution that uses the least number of hexahedra to build a pyramid, which is the key block required for one type of automatic hex-meshing method to be successful. When the initial result of a hex-meshing program is not appropriate for specific applications, some templates are used for revision. The templates reported th...

To satisfy the requirement of finite element analysis, an adaptive mesh generation technique based on ball-packing method for STL models is proposed. First the method recognized the curvatures of edges, curvatures of surfaces and area shape features of STL models, and then a size field was built by an octree, finally adaptive mesh was generated in...

To coarsen a mesh, we usually remove a set of selected nodes one by one. Currently, the basic operation used to remove a node is edge collapsing, which does not perform well when applied to handling narrow regions in a tetrahedron mesh and could produce low‐quality elements or even fail to give valid results. To overcome the drawbacks of edge colla...

For the purpose of developing a hexahedral mesh generation technique which ensures the boundary quality, considers global information and has the potential to speed highly, we presented a hexahedral mesh generation method based on sheet-division. First, we extended the loop of the surface of a solid to a layer of hexahedral elements, and then divid...

For improving topological connection of quadrilateral mesh, we presented a optimization method based on irregular node removal by upgrading and adapting the method of Liu et al. [1]( Liu Jianfei, Sun Shuli, Chen Yongqiang. A new method of quality improvement for quadrilateral mesh based on small polygon reconnection. Acta Mechanica Sinica, 2012, 28...

Atomistic models, which are crucial for performing molecular dynamics (MD) simulations of carbon nanostructures (CNS), consist of virtual hexagonal meshes with defects properly distributed in the intersectional areas. Currently, atomistic models are created mostly by hand, which is a notably tedious and time-consuming process. In this paper, we dev...

We report a fast computational method for generating atomistic models of complex-shaped carbon graphitic nanostructures from their computer-aided design (CAD) representation. The novelty of the method is the adaptation of a fast finite element (FE) triangular surface mesh generation algorithm for complex geometric surfaces.

Incremental algorithm is one of the most popular procedures for constructing Delaunay triangulations (DTs). However, the point insertion sequence has a great impact on the amount of work needed for the construction of DTs. It affects the time for both point location and structure update, and hence the overall computational time of the triangulation...

In this paper, a new method of topological cleanup for quadrilateral mesh is presented. The method first selects a patch of mesh around an irregular node. It then seeks the best connection of the selected patch according to its irregular valence using a new topological operation: small polygon reconnection (SPR). By replacing the original patch wit...

In this paper, we revisit the point-in-polyhedron problem. After reviewing previous work, we develop further insight into the problem. We then claim that, for a given testing point and a three-dimensional polyhedron, a single determining triangle can be found which suffices to determine whether the point is inside or outside the polyhedron.This wor...

Dynamic grid algorithm is essential for numerical simulation of fluid-structure interaction problems with moving boundaries that require the mesh to be movable or deformable. This paper investigates the computational cost of the dynamic grid deformation method proposed by X. Q. Liu, N. Qin et al. (see Journal of Computational Physics, 211, 2006, pp...

Local transformation, or topological reconnection, is one of the effective procedures for mesh improvement method, especially for three-dimensional tetrahedral mesh. The most frequently used local transformations for tetrahedral mesh are so-called elementary flips, such as 2-3 flip, 3-2 flip, 2-2 flip, and 4-4 flip. Owing to the reason that these b...

There are two important problems in the context of Delaunay based mesh generation namely boundary recovery after Delaunay tetrahedralization and sliver removal. Both of them can be solved to a large extent using a new method, the so called small polyhedron reconnection or SPR for abbreviation. For sliver remove, an operation is developed according...

Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents an efficient sphere packing algorithm which is much faster and appears to be the most practical among all sphere packing methods prese...

In this paper, we investigate boundary recovery, the problem that has troubled researchers ever since Delaunay-based methods were applied to generate mesh. There are a number of algorithms for boundary recovery already and most of them depend heavily on adding extra nodes. In this paper, we make an effort to seek a method to recover boundaries with...

Local transformation, or topological reconnection, is one of effective procedures of mesh improvement method, especially in three-dimensional situation. The commonly used local transformations for tetrahedral mesh involve changing in mesh topology (i.e. node-element connectivity relationship) within a relatively small region composed of several tet...

Local transformation, or topological reconnection, is one of effective procedures of mesh improvement method, especially for three-dimensional tetrahedral mesh. Although the existing local transformations such as 2-3/3-2 flip are effective in removing poorly-shaped tetrahedra, it is still possible to improve the quality of mesh further by expanding...

A simple and efficient local optimization-based procedure for node repositioning/smoothing of three-dimensional tetrahedral meshes is presented. The initial tetrahedral mesh is optimized with respect to a specified element shape measure by chaos search algorithm, which is very effective for the optimization problems with only a few design variables...

In this paper the presentation of the ball-packing method is reviewed, and a scheme to generate mesh for complex 3-D geometric models is given, which consists of 4 steps: (1) create nodes in 3-D models by ball-packing method, (2) connect nodes to generate mesh by 3-D Delaunay triangulation, (3) retrieve the boundary of the model after Delaunay tria...

This paper presents an automatic mesh generation procedure on a 2D domain based on a regular background grid. The idea is to devise a robust mesh generation scheme with equal emphasis on quality and efficiency. Instead of using a traditional regular rectangular grid, a mesh of equilateral triangles is employed to ensure triangular element of the be...