Automatic Mesh Generation

As the finite element simulation codes have developed to the point where we can solve many types of fluid flow applications, and the power of the latest generation of massively parallel supercomputers has allowed the freedom to solve very large simulations in a rather short period of time, the mesh generation process has become to play a more important role in my work. For many application problems, algebraic mesh generators are not able to create meshes around complex geometries, and therefore, an automatic mesh generator was needed. Because of this need, I have written a fully automatic, 3D mesh generation system.

This mesh generation system consists of three parts. The first part is an interactive geometric modeler. The modeler runs on Silicon Graphics workstations and uses Bezier edges and patches to model the desired objects in 3D. The modeler also has many time saving features to help the user create complex objects. The second part of the system performs automatic mesh generation on these Bezier patches so as to discretize the model into a surface mesh in 3D composed of triangles. The control of refinement in this surface mesh is very easy and quite flexible. This surface mesh becomes an input to the third part of the system which is the 3D automatic mesh generator which currently runs on the Cray C90 for optimum performance. The mesh generator is based on Delaunay-Voronoi methods and uses edge-swapping techniques. This method produces high quality meshes in 3D and the refinement in the domain is governed by the refinement on the inputed surface mesh. This package also has the capability to create thin layers of semi-structured elements around solid objects. These boundary layer elements are created so as to better model the boundary layer features of the flow.

Many applications have been and are being studied with the help of my mesh generation system. Some of these applications include flow past road vehicles, supersonic flow past fighter aircraft, subsonic flow past commercial airliners, flow past large ram-air parafoils, flow through reservoir spillways, and hypersonic flow past SSTO vehicles. All of these applications are being studied at the AHPCRC by members of Dr. Tezduyar's research group.

Current Status of Research (8-27-97)

Work has continued off-and-on over the past year or two on more advanced mesh generation techniques. Mostly on making the 3D mesh generator more fast and robust. Also, a project has been initiated to combine all mesh generation procedures into a easy-to-use, interactive mesh generation software package. This will include a new interactive modeler based on NURBS, and both surface mesh generation and 3D volumetric mesh generation functions.

Also, a project has been initiated at the AHPCRC on parallel mesh generation procedures. I hope to develop a parallel (distributed memory) mesh Re-generation library which will Re-generate a mesh (rearrange elements for better quality, and redo the entire nodal distribution by adding and deleting nodes where appropriate) when called upon. For me, this will mainly be used in simulations involving mesh movement by handling the remeshing procedures in parallel, but this software could also be used in parallel adaptive computations. This is a joint project with Vipin Kumar and George Karypis from the Computer Science Department.

Andrew's Mesh Generation Links

Andrew's Home Page: More information about Andrew Johnson can be found here. Some of my other research projects, more information about automatic mesh generation, information about my software, personal information, and other links can all be found here.
Andrew's Software Page: Information about some of Andrew's general purpose software packages (flow solvers, automatic mesh generation, modelers, graphics packages) can be found here. Most of this software is for internal use at the AHPCRC, but I hope to put my freely available, downloadable, 3D automatic mesh generation programs here when the software is completed.
AHPCRC Workshop on Unstructured Mesh Generation and Partitioning: We are putting together a conference on unstructured mesh generation and partitioning on October 6-7. Should be fun.
Army High Performance Computing Research Center (AHPCRC): The research center at the University of Minnesota where I work. All researchers are from the U of M, but the funding comes from the Army Research Laboratory. This is where I have been studying (during graduate school) and working (as a Research Assistant Professor) for the last 6+ years. More information about the center's activities and research can be found here.
AHPCRC Free Software: The AHPCRC has developed several software packages which are freely downloadable from this page. Most of these are graphics programs and computer system utilities.
AHPCRC Mesh Modeler: As stated above, a project has been initiated at the AHPCRC to develop an (relatively) easy-to-use mesh generation software environment. To date, a beta version of the new modeler has been completed, and information about this software can be found here.
Metis: Information about the Metis mesh partitioning library, as well as the library itself, can be found here. Metis has been developed by George Karypis (my colleague down the hall from me at the AHPCRC) from the Computer Science Department and the AHPCRC.

Examples:

Mesh of an Automobile.
Mesh of a Fighter Aircraft.
Large Scale Fluid-Particle Interactions.
Publications.