Zhang Xing

Bio: Zhang Xing is an academic researcher. The author has contributed to research in topics: Grid & Boundary (topology). The author has an hindex of 3, co-authored 12 publications receiving 22 citations.

Efficient mesh deformation based on Cartesian background mesh

Abstract: Moving mesh is widely used in the simulation of aerodynamic shape optimization, multibody relative motion, aircraft icing and aeroelasticity. The efficient and high quality mesh deformation is the key technology of moving mesh. This paper presented a new Mesh Deformation method based on Cartesian Background Mesh (MDCBM). First, the Cartesian background mesh is deformed with radial basis functions (RBF). Second, the displacement of Cartesian background mesh is algebraically interpolated onto all meshes in the computing domain. Since the background mesh is coarse, the background mesh deformation can be finished fast. Because the background mesh of MDCBM is regular, the mapping relationship between background mesh and the computing mesh is simple. So the time spent on mapping search is substantially reduced. The examples including NACA0012 airfoil, multi-element airfoil with structured, unstructured mesh and DLR-F4 wing–body show the good performance of MDCBM. We highlight the advantages of MDCBM with respect to its computational efficiency and high quality of deformed mesh.

Multi-body separation grid overlapping method and system suitable for parallel processing

Abstract: The invention discloses a multi-body separation grid overlapping method and system suitable for parallel processing. The method comprises the steps of refining surface elements of surfaces of grid blocks; marking edge units of the grid blocks; storing the edge units in a classified manner; according to the stored edge units, judging whether the grid blocks of different objects have an overlappingposition relationship or not; and performing holing and hole boundary backtracing for the grid blocks, with the overlapping position relationship, of the different objects, and performing contributionunit search for an overlapping boundary, thereby realizing multi-body separation grid overlapping of the parallel processing. The surfaces of the grid blocks are subjected to geometric approximationby utilizing Cartesian bounding boxes, and through position identification of the Cartesian bounding boxes of the surfaces of the grid blocks of the different objects, whether the grid blocks are overlapping or not is quickly judged. In parallel calculation, only the grid blocks with the overlapping position relationship are subjected to overlapping operation, so that frequent call of a global grid is avoided and the difficult problems of high memory demand and low calculation efficiency of a large overlapping grid are solved.

Grid boundary condition processing method of unstructured grid CFD computation

Abstract: The invention belongs to the technical field of grid computation, and specifically relates to a grid boundary condition processing method of unstructured grid CFD computation. The method comprises the following steps: establishing grid information; defining a boundary type; extracting grid outer boundary information; realizing the matching of a first node through a method of exhaustion; matching the remaining nodes in a wave front form; matching a boundary surface unit; and assigning a boundary condition. According to the method, a method for rapidly matching between unstructured boundary surfaces and grid surfaces is utilized, so that the grid boundary conditions of unstructured grids in Tecplot form can be rapidly mapped to corresponding boundary surfaces of infield body grids, the rapid processing of boundary condition information of the unstructured grids can be realized and the computer time can be effectively decreased.

Sample simplifying method of radial basis function support points

Abstract: The invention belongs to the technical field of structured grids, structured/unstructured hybrid grids and point clouds, and specifically relates to a sample simplifying method of radial basis function support points. The data sample simplifying scheme of the invention comprises the following steps: boundary grid points are grouped through a group of cuboids firstly, the number of each group of grouped grid points is about 100, and an average position and an average deformation amount of each group of the grid points are calculated; and, when the next group of sample points are searched, the group is taken as a unit firstly, 3-5 groups the grid points of which have the maximum deformation amount error of the average position of the various groups of the grid points, the grid points in the 3-5 groups are then searched one by one, the grid point having the maximum grid deformation amount error in each group is determined, and the grid point, having the maximum grid deformation amount error in each group, as a new sample is added to a sample space. Time for search the sample points can be reduced through adoption of the technical scheme.

Method for shortening CFD (computation fluid dynamics) numerical-simulation calculating time on basis of pre-operation

Abstract: The invention belongs to the technical field of CFD (computation fluid dynamics) calculation of high-performance computer systems, and particularly relates to a method for shortening CFD numerical-simulation calculating time on the basis of pre-operation. The method includes steps of (1) establishing a pre-operation test set; (2) defining a computer node set; (3) based on the established pre-operation test set, the method for shortening CFD numerical-simulation calculating time on the basis of pre-operation mainly includes three parts of (3.1) selecting test proportion conforming to CFD calculation requirements; (3.2) calculating the integral performance of various calculation node sets after pre-operation and selecting the set of the highest integral performance, namely the fastest operation for the proportion; (3.3) submitting the calculation node sets of the highest integral performance to specific CFD calculation tasks according to the step (3.2). By the method, CFD program operation time can be effectively shortened, execution efficiency of programs on the high-performance computers is improved.

RBF-based mesh morphing approach to perform icing simulations in the aviation sector

Abstract: Numerical simulation of icing has become a standard. Once the iced shape is known, however, the analyst needs to update the computational fluid dynamics (CFD) grid. This paper aims to propose a method to update the numerical mesh with ice profiles.,The present paper concerns a novel and fast radial basis functions (RBF) mesh morphing technique to efficiently and accurately perform ice accretion simulations on industrial models in the aviation sector. This method can be linked to CFD analyses to dynamically reproduce the ice growth.,To verify the consistency of the proposed approach, one of the most challenging ice profile selected in the LEWICE manual was replicated and simulated through CFD. To showcase the effectiveness of this technique, predefined ice profiles were automatically applied on two-dimensional (2D) and three-dimensional (3D) cases using both commercial and open-source CFD solvers.,If ice accreted shapes are available, the meshless characteristic of the proposed approach enables its coupling with the CFD solvers currently supported by the RBF4AERO platform including OpenFOAM, SU2 and ANSYS Fluent. The advantages provided by the use of RBF are the high performance and reliability, due to the fast application of mesh smoothing and the accuracy in controlling surface mesh nodes.,As far as authors’ knowledge is concerned, this is the first time in scientific literature that RBF are proposed to handle icing simulations. Due to the meshless characteristic of the RBF mesh morphing, the proposed approach is cross solver and can be used for both 2D and 3D geometries.

Quality-Preserving Linear Elasticity Mesh Movement Algorithm for Multi-Element Unstructured Meshes

Abstract: A linear elasticity mesh movement algorithm is presented for unstructured computational aerodynamic meshes consisting of multiple element types. An adaptive method for incrementally stiffening mesh...

Forward tracking generation method and device for point cloud geodesic path

Abstract: The invention relates to the field of point cloud data processing. A main traveling direction between a start point ps(xs,ys,zs) and an end point pe (xe,ye,ze) of the geodesic path is selected, and agridding area is determined by the main traveling direction; coordinate values of all data points in the gridding area are extracted, three coordinate component arrays are formed, the arrays are sorted, the same coordinate component values are removed, and maximum and minimum values of the coordinates of all point cloud data points in the gridding area are found; step sizes hxi, hyj and hzk of thedata points in three axial directions are calculated respectively, the data points between the two points ps and pe are subjected to non-uniformly gridding, and the step 3 is executed; arrival time of each cell in the wavefront grid is calculated by UNCDFMM according to the step sizes hxi, hyj and hzk; the cells meeting the approximate geodesic property are screened out after the arrival time ofeach cell is calculated, and vertices of the cells are sequentially connected to form the geodesic path.