The goal of the ITAPS Center is to develop and deploy a set of computational tools that will significantly and positively impact the ability of scientific applications researchers to employ advanced mesh and geometry-based simulation technology in their research. Because of the sophistication of most existing advanced tools in this area, their availability has until now been limited to only the most ambitious application developers. We are addressing this deficiency by offering significant capability for generating different kinds of meshes for complex geometry and employing these meshes in scientific simulations through easy-to-use application-appropriate interfaces. Since many important Office of Science applications are characterized by strongly non-uniform solution features, these tools will include capabilities for solution-adaptive mesh and solution improvement capabilities, including mesh refinement and front tracking.
We have invested a significant portion of our resources in meeting with scientists from many of the SciDAC application areas, analyzing their needs for advanced meshing and discretization technologies, and working with them to demonstrate the promise of such techniques in their application domains. We highlight the positive impact we have had on applications researchers here. More information on these interactions can be found by following the links.
Impact on SciDAC Applications
Community Petascale Project for Accelerator Science and Simulation (COMPASS). The ITAPS team supported significant accelerator modeling achievements in several areas. [More Information]
- ITAPS enabled the first-ever Tau3P transit beam simulation of the Stanford Linear Accelerator Center (SLAC) PEP-II device, supporting a 15% increase in beam current in the upgraded device by providing high-quality hexahedral meshes. Similar mesh generation efforts for the advanced Damped Detuned Structure (DDS) resulted in the first wakefield analysis of an actual DDS prototype and the direct verification of DDS wakefield suppression by end-to-end simulation.
- ITAPS researchers teamed with SLAC scientists to improve by an order of magnitude the accuracy of predicted field quantities that influence wall losses in the Rare Isotope Accelerator device. To accomplish this ITAPS researchers provided an adaptive simulation capability with error indicators, field function libraries, and mesh modification procedures. These procedures are being extended to effectively operate in parallel to support full-scale accelerator systems.
- A collaboration between ``Toward Optimal Petascale Simulations'' (TOPS), ITAPS, and SLAC researchers is providing automatic tuning of accelerator geometries to significantly increase the speed and decrease the cost by which new accelerators can be designed. ITAPS researchers provide services for varying design geometry, smoothing the mesh onto new models, and automatically computing sensitivities of the mesh with respect to design parameters.
- Center for Extended Magnetohydrodynamic Modeling (CEMM). ITAPS researchers are contributing to a new effort at Princeton Plasma Physics Lab (PPPL) to develop an adaptive, high-order finite element discretization for their new M3D-C1 code. Solutions of the CEMM challenge problems developed by ITAPS researchers using high-order spectral element technologies elements that focused on the case of anisotropic diffusion led to the conclusion that a small number of higher-order elements significantly decreased the total solution time needed to obtain a given accuracy. Ongoing work focuses on insertion of adaptive mesh refinement technologies and error estimators directly into the new code. [More Information]
- Virtual Microbial Cell Simulator (VMCS). ITAPS mesh generation and discretization technologies were used in simulations that provided new scientific insight into the flocculation behavior of Shewanella microbes in oxygen rich environments by confirming that there is an oxygen gradient from the edges of the floc into the center. This collaboration with PNNL computational biologists has resulted in the development of the VMCS which is targeting DOE bioremediation problems in heavy metal waste. [More Information]
- Collaborative Design and Development of the Community Climate Model. ITAPS researchers, in collaboration with climate scientists at ORNL, improved the prediction of rainfall, snowfall and cloud cover in regional weather models in prototype simulations for an atmospheric pulse rotating around the Earth. ITAPS provided the enhanced mesh generation and discretization capabilities for anisotropic planar and geodesic surface meshes that helped enable this result. The initial mesh is adapted and optimized to capture land surface orographic or topographic height fields for these simulations. [More Information]
For two of the astrophysics SciDAC-1 centers, we demonstrated the potential impact of high-order discretization methods for both the hydrodynamics and neutrino transport aspects of their simulations. In both cases, adaptive Discontinuous Galerkin discretizations were implemented for the appropriate test problems and comparison to the currently used techniques shows that a significant benefit in terms of accuracy and time to solution can be obtained by using these techniques. [More Information]
- Reactor Modeling.
- Combustion. ITAPS researchers developed simulation tools that provide a new predictive capability for diesel engine design that emphasizes the modeling of the instability and break up of a diesel jet into spray. This simulation highlighted the advantages of front tracking algorithms combined with two-dimensional structured adaptive mesh refinement. [More Information]