The Experts below are selected from a list of 25899 Experts worldwide ranked by ideXlab platform

Hans-ulrich Heiss - One of the best experts on this subject based on the ideXlab platform.

  • Online Mesh Refinement for Parallel Atmospheric Models
    International Journal of Parallel Programming, 2012
    Co-Authors: Claudio Schepke, Nicolas Maillard, Joerg Schneider, Hans-ulrich Heiss
    Abstract:

    Forecast precisions of climatological models are limited by computing power and time available for the executions. As more and faster processors are used in the computation, the resolution of the Mesh adopted to represent the Earth’s atmosphere can be increased, and consequently the numerical forecast is more accurate. However, a finer Mesh resolution, able to include local phenomena in a global atmosphere integration, is still not possible due to the large number of data elements to compute in this case. To overcome this situation, different Mesh Refinement levels can be used at the same time for different areas of the domain. Thus, our paper evaluates how Mesh Refinement at run time (online) can improve performance for climatological models.The online Mesh Refinement (OMR) increases dynamically Mesh resolution in parts of a domain,when special atmosphere conditions are registered during the execution. Experimental results show that the execution of a model improved by OMR provides better resolution for the Meshes, without any significant increase of execution time. The parallel performance of the simulations is also increased through the creation of threads in order to explore different levels of parallelism.

  • Why Online Dynamic Mesh Refinement is Better for Parallel Climatological Models
    2011 23rd International Symposium on Computer Architecture and High Performance Computing, 2011
    Co-Authors: Claudio Schepke, Nicolas Maillard, Joerg Schneider, Hans-ulrich Heiss
    Abstract:

    Forecast precisions of climatological models are limited by computing power and time available for the executions. As more and faster processors are used in the computation, the resolution of the Mesh adopted to represent the Earth's atmosphere can be increased, and consequently the numerical forecast is more accurate and shows local phenomena. However, a finer Mesh resolution, able to include local phenomena in a global atmosphere integration, is still not possible. To overcome this situation, different Mesh Refinement levels can be used at the same time for different areas. In this context, this paper evaluates how Mesh Refinement at run time can improve performance for climatological models. In order to contribute with this analysis, an online dynamic Mesh Refinement was developed. It increases Mesh resolution in parts of a parallel distributed model, when special atmosphere conditions are registered during the execution. The results show that the parallel execution of this improvement provides better resolution for the Meshes, without a significant increase of execution time.

Jennifer J Zhao - One of the best experts on this subject based on the ideXlab platform.

  • high order compact scheme with multigrid local Mesh Refinement procedure for convection diffusion problems
    Computer Methods in Applied Mechanics and Engineering, 2002
    Co-Authors: Jun Zhang, Jennifer J Zhao
    Abstract:

    We derive a new fourth order compact finite difference scheme which allows different Meshsize in different coordinate directions for the two-dimensional convection diffusion equation. A multilevel local Mesh Refinement strategy is used to deal with the local singularity problem. A corresponding multilevel multigrid method is designed to solve the resulting sparse linear system. Numerical experiments are conducted to show that the local Mesh Refinement strategy works well with the high order compact discretization scheme to recover high order accuracy for the computed solution. Our solution method is also shown to be effective and robust with respect to the level of Mesh Refinement and the anisotropy of the problems.

M.m. Yovanovich - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive Mesh Refinement of Supersonic Channel Flows on Unstructured Meshes
    2020
    Co-Authors: R. C. Ripley, Fue-sang Lien, M.m. Yovanovich
    Abstract:

    (Received ?????) An isotropic local Mesh Refinement technique for unstructured Meshes is presented. The present work pertains to inviscid, steady, supersonic internal flows contained in a channel configuration. A densitybased Mesh Refinement sensor function is used to identify regions in the Mesh for Refinement. A facecell finite-volume method, permitting dynamic changes to Mesh connectivity, is employed in the Mesh Refinement strategy. The AUSMþ convection scheme is used to compute the interface numerical flux using Mach number and pressure splitting functions. The present method is capable of recursive multilevel Mesh adaption. Local Mesh Refinement equivalent to 64 and 256 times the coarse Mesh resolution can be obtained using four and five levels of Refinement, respectively. Results for two popular supersonic channel test cases are presented: Mach 1.4 flow over a 4% thick circular arc bump, and Mach 2.0 flow over a 108 compression ramp. The effort associated with the Mesh Refinement of the bump case accounts for only 4.6% of the total simulation time. For the ramp case, a factor of 4.2 for memory storage requirements and 7.7 for simulation time is required to obtain an equivalent uniform fine Mesh solution.

  • Adaptive Unstructured Mesh Refinement of Supersonic Channel Flows
    International Journal of Computational Fluid Dynamics, 2004
    Co-Authors: R. C. Ripley, Fue-sang Lien, M.m. Yovanovich
    Abstract:

    An isotropic local Mesh Refinement technique for unstructured Meshes is presented. The present work pertains to inviscid, steady, supersonic internal flows contained in a channel configuration. A density-based Mesh Refinement sensor function is used to identify regions in the Mesh for Refinement. A face-cell finite-volume method, permitting dynamic changes to Mesh connectivity, is employed in the Mesh Refinement strategy. The AUSM+ convection scheme is used to compute the interface numerical flux using Mach number and pressure splitting functions. The present method is capable of recursive multi-level Mesh adaption. Local Mesh Refinement equivalent to 64 and 256 times the coarse Mesh resolution can be obtained using four and five levels of Refinement, respectively. Results for two popular supersonic channel test cases are presented: Mach 1.4 flow over a 4% thick circular arc bump, and Mach 2.0 flow over a 10° compression ramp. The effort associated with the Mesh Refinement of the bump case accounts for on...

Claudio Schepke - One of the best experts on this subject based on the ideXlab platform.

  • Online Mesh Refinement for Parallel Atmospheric Models
    International Journal of Parallel Programming, 2012
    Co-Authors: Claudio Schepke, Nicolas Maillard, Joerg Schneider, Hans-ulrich Heiss
    Abstract:

    Forecast precisions of climatological models are limited by computing power and time available for the executions. As more and faster processors are used in the computation, the resolution of the Mesh adopted to represent the Earth’s atmosphere can be increased, and consequently the numerical forecast is more accurate. However, a finer Mesh resolution, able to include local phenomena in a global atmosphere integration, is still not possible due to the large number of data elements to compute in this case. To overcome this situation, different Mesh Refinement levels can be used at the same time for different areas of the domain. Thus, our paper evaluates how Mesh Refinement at run time (online) can improve performance for climatological models.The online Mesh Refinement (OMR) increases dynamically Mesh resolution in parts of a domain,when special atmosphere conditions are registered during the execution. Experimental results show that the execution of a model improved by OMR provides better resolution for the Meshes, without any significant increase of execution time. The parallel performance of the simulations is also increased through the creation of threads in order to explore different levels of parallelism.

  • Why Online Dynamic Mesh Refinement is Better for Parallel Climatological Models
    2011 23rd International Symposium on Computer Architecture and High Performance Computing, 2011
    Co-Authors: Claudio Schepke, Nicolas Maillard, Joerg Schneider, Hans-ulrich Heiss
    Abstract:

    Forecast precisions of climatological models are limited by computing power and time available for the executions. As more and faster processors are used in the computation, the resolution of the Mesh adopted to represent the Earth's atmosphere can be increased, and consequently the numerical forecast is more accurate and shows local phenomena. However, a finer Mesh resolution, able to include local phenomena in a global atmosphere integration, is still not possible. To overcome this situation, different Mesh Refinement levels can be used at the same time for different areas. In this context, this paper evaluates how Mesh Refinement at run time can improve performance for climatological models. In order to contribute with this analysis, an online dynamic Mesh Refinement was developed. It increases Mesh resolution in parts of a parallel distributed model, when special atmosphere conditions are registered during the execution. The results show that the parallel execution of this improvement provides better resolution for the Meshes, without a significant increase of execution time.

Jun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • high order compact scheme with multigrid local Mesh Refinement procedure for convection diffusion problems
    Computer Methods in Applied Mechanics and Engineering, 2002
    Co-Authors: Jun Zhang, Jennifer J Zhao
    Abstract:

    We derive a new fourth order compact finite difference scheme which allows different Meshsize in different coordinate directions for the two-dimensional convection diffusion equation. A multilevel local Mesh Refinement strategy is used to deal with the local singularity problem. A corresponding multilevel multigrid method is designed to solve the resulting sparse linear system. Numerical experiments are conducted to show that the local Mesh Refinement strategy works well with the high order compact discretization scheme to recover high order accuracy for the computed solution. Our solution method is also shown to be effective and robust with respect to the level of Mesh Refinement and the anisotropy of the problems.