The Experts below are selected from a list of 18498 Experts worldwide ranked by ideXlab platform
Rainald Lohner - One of the best experts on this subject based on the ideXlab platform.
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running Unstructured Grid based cfd solvers on modern graphics hardware
International Journal for Numerical Methods in Fluids, 2011Co-Authors: Andrew Corrigan, Fernando Camelli, Rainald Lohner, John WallinAbstract:Techniques used to implement an Unstructured Grid solver on modern graphics hardware are described. The three-dimensional Euler equations for inviscid, compressible ow are considered. Eective memory bandwidth is improved by reducing total global memory access and overlapping redundant computation, as well as using an appropriate numbering scheme and data layout. The applicability of per-block shared memory is also considered. The performance of the solver is demonstrated on two benchmark cases: a missile and the NACA0012 wing. For a variety of mesh sizes, an average speed-up factor of roughly 9.5x is observed over the equivalent parallelized OpenMP-code running on a quad-core CPU, and roughly 33x over the equivalent code running in serial.
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Running Unstructured Grid‐based CFD solvers on modern graphics hardware
International Journal for Numerical Methods in Fluids, 2011Co-Authors: Andrew T. Corrigan, Fernando Camelli, Rainald Lohner, John WallinAbstract:Techniques used to implement an Unstructured Grid solver on modern graphics hardware are described. The three-dimensional Euler equations for inviscid, compressible ow are considered. Eective memory bandwidth is improved by reducing total global memory access and overlapping redundant computation, as well as using an appropriate numbering scheme and data layout. The applicability of per-block shared memory is also considered. The performance of the solver is demonstrated on two benchmark cases: a missile and the NACA0012 wing. For a variety of mesh sizes, an average speed-up factor of roughly 9.5x is observed over the equivalent parallelized OpenMP-code running on a quad-core CPU, and roughly 33x over the equivalent code running in serial.
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adaptive embedded and immersed Unstructured Grid techniques
Computer Methods in Applied Mechanics and Engineering, 2008Co-Authors: Rainald Lohner, Fernando Camelli, Juan R Cebral, Sunil Appanaboyina, Joseph D Baum, Eric Mestreau, Orlando SotoAbstract:Embedded mesh, immersed body or fictitious domain techniques have been used for many years as a way to discretize geometrically complex domains with structured Grids. The use of such techniques within adaptive, Unstructured Grid solvers is relatively recent. The combination of body-fitted functionality for some portion of the domain, together with embedded mesh or immersed body functionality for another portion of the domain offers great advantages, which are increasingly being exploited. The present paper reviews the methodologies pursued so far, addresses implementational issues and shows the possibilities such techniques offer.
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high reynolds number viscous flow computations using an Unstructured Grid method
Journal of Aircraft, 2005Co-Authors: Hong Luo, Joseph D Baum, Rainald LohnerAbstract:An Unstructured Grid method is presented to compute three-dimensional compressible turbulent flows for complex geometries. The Navier-Stokes equations, along with the one-equation turbulence model of Spalart-Allmaras are solved by the use of a parallel, matrix-free implicit method on Unstructured tetrahedral Grids. The developed method has been used to predict drags in the transonic regime for both DLR-F4 and DLR-F6 configurations to assess the accuracy and efficiency of the method
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adaptive embedded Unstructured Grid methods
International Journal for Numerical Methods in Engineering, 2004Co-Authors: Rainald Lohner, Dmitri Sharov, Joseph D Baum, Eric Mestreau, Charles Charman, Daniele PelessoneAbstract:A simple embedded domain method for node-based Unstructured Grid solvers is presented. The key modification of the original, edge-based solver is to remove all geometry-parameters (essentially the normals) belonging to edges cut by embedded surface faces. Several techniques to improve the treatment of boundary points close to the immersed surfaces are explored. Alternatively, higher-order boundary conditions are achieved by duplicating crossed edges and their endpoints. Adaptive mesh refinement based on proximity to or the curvature of the embedded CSD surfaces is used to enhance the accuracy of the solution. User-defined or automatic deactivation for the regions inside immersed solid bodies is employed to avoid unnecessary work. Several examples are included that show the viability of this approach for inviscid and viscous, compressible and incompressible, steady and unsteady flows, as well as coupled fluid-structure problems.
Changsheng Chen - One of the best experts on this subject based on the ideXlab platform.
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an Unstructured Grid finite volume sea ice model development validation and application
Journal of Geophysical Research, 2011Co-Authors: Guoping Gao, Changsheng Chen, Robert C BeardsleyAbstract:[1] A sea ice model was developed by converting the Community Ice Code (CICE) into an Unstructured-Grid, finite-volume version (named UG-CICE). The governing equations were discretized with flux forms over control volumes in the computational domain configured with nonoverlapped triangular meshes in the horizontal and solved using a second-order accurate finite-volume solver. Implementing UG-CICE into the Arctic Ocean finite-volume community ocean model provides a new Unstructured-Grid, MPI-parallelized model system to resolve the ice-ocean interaction dynamics that frequently occur over complex irregular coastal geometries and steep bottom slopes. UG-CICE was first validated for three benchmark test problems to ensure its capability of repeating the ice dynamics features found in CICE and then for sea ice simulation in the Arctic Ocean under climatologic forcing conditions. The model-data comparison results demonstrate that UG-CICE is robust enough to simulate the seasonal variability of the sea ice concentration, ice coverage, and ice drifting in the Arctic Ocean and adjacent coastal regions.
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a fvcom based Unstructured Grid wave current sediment transport model i model description and validation
Journal of Ocean University of China, 2011Co-Authors: Changsheng Chen, Peifang Guo, Maochong ShiAbstract:An effort was made to couple FVCOM (a three-dimensional (3D), Unstructured Grid, Finite Volume Coastal Ocean Model) and FVCOM-SWAVE (an Unstructured Grid, finite-volume surface wave model) for the study of nearshore ocean processes such as tides, circulation, storm surge, waves, sediment transport, and morphological evolution. The coupling between FVCOM and FVCOM-SWAVE was achieved through incorporating 3D radiation stress, wave-current-sediment-related bottom boundary layer, sea surface stress parameterizations, and morphology process. FVCOM also includes a 3D sediment transport module. With accurate fitting of irregular coastlines, the model provides a unique tool to study sediment dynamics in coastal ocean, estuaries, and wetlands where local geometries are characterized by inlets, islands, and intertidal marsh zones. The model was validated by two standard benchmark tests: 1) spectral waves approaching a mild sloping beach and 2) morphological changes of seabed in an idealized tidal inlet. In Test 1, model results were compared with both analytical solutions and laboratory experiments. A further comparison was also made with the structured Grid Regional Ocean Model System (ROMS), which provides an insight into the performance of the two models with the same open boundary forcing.
M Uddstrom - One of the best experts on this subject based on the ideXlab platform.
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operational forecasting of sea level height using an Unstructured Grid ocean model
Ocean Modelling, 2009Co-Authors: Emily M Lane, Roy A Walters, Philip A Gillibrand, M UddstromAbstract:Abstract Unstructured Grid models are often used for modelling coastal problems, due to their efficiency at handling complex coastlines while also not over resolving deeper water. In this paper, we outline how an Unstructured Grid finite element model has been incorporated into an operational environmental forecast system, EcoConnect, to provide near real-time predictions of storm surge and sea level height. Data transfer methods between the meteorological model, which uses a structured Grid, and the storm surge model are described and we present results of verification simulations for the forecasting of sea level height. The model successfully reproduced the storm surge signal at 15 tide gauge locations around New Zealand during December 2006–February 2007, with RMS errors in the range 3–7 cm. Preliminary tests of a tide model using the same Unstructured Grid are also presented, as a precursor to its inclusion into the operational system.
Myung-seok Lyu - One of the best experts on this subject based on the ideXlab platform.
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Unstructured Grid Finite Volume Analysis for Acoustic and Pulsed Wave Propagation Characteristics in Exhaust Silencer Systems
Numerical Heat Transfer Part A: Applications, 1996Co-Authors: Jong-tae Kim, Yong-mo Kim, Joo-sung Maeng, Myung-seok LyuAbstract:The Unstructured Grid finite volume method has been applied to predict the linear and nonlinear attenuation characteristics of the expansion chamber type silencer system. In order to achieve Grid flexibility and a solution adaptation for geometrically complex flow regions associated with the actual silencers, the Unstructured mesh algorithm in context with the node-centered finite volume method has been employed. The validation cases for the linear and nonlinear wave propagation characteristics include the acoustic field of the concentric expansion chamber and the axisymmetric blast flow field with the open end. Effects of the chamber geometry on the nonlinear wave propagation characteristics are discussed in detail.
Guoping Gao - One of the best experts on this subject based on the ideXlab platform.
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an Unstructured Grid finite volume sea ice model development validation and application
Journal of Geophysical Research, 2011Co-Authors: Guoping Gao, Changsheng Chen, Robert C BeardsleyAbstract:[1] A sea ice model was developed by converting the Community Ice Code (CICE) into an Unstructured-Grid, finite-volume version (named UG-CICE). The governing equations were discretized with flux forms over control volumes in the computational domain configured with nonoverlapped triangular meshes in the horizontal and solved using a second-order accurate finite-volume solver. Implementing UG-CICE into the Arctic Ocean finite-volume community ocean model provides a new Unstructured-Grid, MPI-parallelized model system to resolve the ice-ocean interaction dynamics that frequently occur over complex irregular coastal geometries and steep bottom slopes. UG-CICE was first validated for three benchmark test problems to ensure its capability of repeating the ice dynamics features found in CICE and then for sea ice simulation in the Arctic Ocean under climatologic forcing conditions. The model-data comparison results demonstrate that UG-CICE is robust enough to simulate the seasonal variability of the sea ice concentration, ice coverage, and ice drifting in the Arctic Ocean and adjacent coastal regions.
