Parallel Adaptive LoopsA parallel solution adaptive loop service is being developed to support SLAC accelerator modeling and PPPL MHD modeling of fusion plasmas (currently underway), and is also being applied to blood flow and large deformation forming problems. The current service is based on generalized mesh modification procedures that accept a discretized mesh size field as input and modifies simplex (tetrahedral) meshes to match the specified mesh sizes including anisotropic mesh configurations. These procedures have been developed to work in conjunction with a CAD definition of the geometric domain so that as the mesh is refined its geometric approximation is automatically improved. A generalized partition model has been added to this service to allow it to support parallel distributed meshes that are dynamically load-balanced as part of adaptive simulations.
We will continue to develop this service to provide applications the ability to employ adaptive simulation technologies with either no modification, or minimal modification, to their analysis procedures. The minimal set of components required to construct an adaptive loop are (i) a mesh-based analysis procedure capable of solving the PDE's, (ii) an error estimation procedure that can use the current solution information to indicate the changes desired to the discretization, (iii) a mesh adaptation procedure (which must be geometry-aware) that can modify the mesh as specified and (iv) a procedure to map solution parameters to the new discretization. This service will build on component services for mesh adaptation, error estimation, solution transfer, and dynamic services, as well as the ITAPS interfaces. We will also complete the parallelization of this service, to eliminate the serial I/O bottleneck of the current process, with a goal of improving the scalability of the current service to treat meshes of over 10^9 elements.