Partial differential equations simplify multiphysics analysis

A recent numerical-- analysis program for engineering disciplines uses partial differential equations to determine stress, strain, heat transfer, and more. The 2D version of Femlab is now upgraded with 3D capability.

"The advantage of the software is the simplicity it brings to multiphysics

studies," says Svante Littmarck, president of Comsol Inc., Burlington, Mass. "For instance, when preparing a model, users would construct it, apply boundary constraints, mesh it, and select the disciplines to apply. This is done by checking off disciplines of interest on a menu of partial-- differential equations provided." These include stress, deflections, heat transfer, fluid dynamics, electromagnetic, and chemical-reaction models.

Users can construct 2D and 3D models with the built-in CAD tools, by using command-line functions, or in the 2D case, by importing a DXF file. Users can also build 3D models by joining primitive objects such as blocks, spheres, cones, and cylinders. Or, they can define cross-section curves in a 2D-work plane and extrude or revolve it into a 3D object. The mesh generator can run on default settings, or users can control the mesh size. In the latter case, users select an overall element size for the entire model, or selectively apply one to each subdomain, face, edge, or vertex.

The latest version of the software comes with iterative solvers that use less memory and handle larger models than the previous version. They also allow setting up steady-state conditions and time-dependent (unsteady or dynamic) conditions. These take longer to solve.

The software works in Matlab which give access to its functions for modeling, analysis, and visualization. This includes the interface to C and Fortran subroutines.

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Engineers studying a device made of coaxial cylinders (upper right) can test it for any of the disciplines under the Physics-modes list to the left.

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Femlab has calculated the 3D flow over a backstep, a problem frequently encountered in flow studies.