TRiangular Unstructured Mesh generator by Point insEr Tion (TRUMPET) is a computer program that generates meshes that are composed of triangular cells and are bounded by complex shapes. The bounding shapes can be singly or multiply connected two-dimensional regions. The figure depicts two examples of meshes that can be generated by use of TRUMPET.
The boundaries are specified by the user. The number of points used to describe a boundary can vary from 2 for a straight line to n>2 for a boundary with curvature. Once specified, the points are then splined. A point-distribution function can then be used to cluster or stretch the points along a given boundary segment.
The boundary points are then used to start a point-insertion process. First, the boundary points are triangulated on the basis of the Delaunay criterion. The result of this triangulation is usually not desirable. Points are then inserted in the domain to obtain a reasonable grid.
Five point-insertion criteria are used in TRUMPET. A new point is inserted at the circumcenter of a cell that meets whichever criterion is chosen. This enables one to control shapes of the cells that are added to the domain. One criterion produces a grid of cells that are more nearly equilateral; another criterion produces a grid with stretched cells (used for computing viscous flow). The criteria can be mixed to produce a grid most appropriate for the problem one is attempting to solve.
Upon completion, the code produces a file of Cartesian coordinate data as well as a complete set of connectivity files. These files give the cell-to-node, cell-to-edge, edge-to-cell, edge-to-node, node-to-node, node-to-edge, and node-to-cell information. Types of boundary conditions can be.
specified by tagging the boundary edges. TRUMPET also includes a sorting routine that orders the cells and edges geometrically. A coloring algorithm is employed to produce a set of four-color files such that no cell lies next to a cell of the same color.
The code calls software libraries in OpenGL and GLUT to display the results of the triangulation procedure as it progresses. This feature enables visual inspection of the node distribution along the boundaries and the resulting grid.
This work was done by Philip C. E. Jorgenson of Glenn Research Center. Further information can be obtained from:
Dr. Philip C. E. Jorgenson,
NASA Glenn Research Center at Lewis Field
21000 Brookpark Road
Cleveland, OH 4413
Telephone No: (216) 433-5386