The Experts below are selected from a list of 19842 Experts worldwide ranked by ideXlab platform
Irina Kalashnikova Tezaur - One of the best experts on this subject based on the ideXlab platform.
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albany felix a parallel scalable and robust finite element first order Stokes Approximation ice sheet solver built for advanced analysis
Geoscientific Model Development, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Stephen PriceAbstract:Abstract. This paper describes a new parallel, scalable and robust finite element based solver for the first-order Stokes momentum balance equations for ice flow. The solver, known as Albany/FELIX, is constructed using the component-based approach to building application codes, in which mature, modular libraries developed as a part of the Trilinos project are combined using abstract interfaces and template-based generic programming, resulting in a final code with access to dozens of algorithmic and advanced analysis capabilities. Following an overview of the relevant partial differential equations and boundary conditions, the numerical methods chosen to discretize the ice flow equations are described, along with their implementation. The results of several verification studies of the model accuracy are presented using (1) new test cases for simplified two-dimensional (2-D) versions of the governing equations derived using the method of manufactured solutions, and (2) canonical ice sheet modeling benchmarks. Model accuracy and convergence with respect to mesh resolution are then studied on problems involving a realistic Greenland ice sheet geometry discretized using hexahedral and tetrahedral meshes. Also explored as a part of this study is the effect of vertical mesh resolution on the solution accuracy and solver performance. The robustness and scalability of our solver on these problems is demonstrated. Lastly, we show that good scalability can be achieved by preconditioning the iterative linear solver using a new algebraic multilevel preconditioner, constructed based on the idea of semi-coarsening.
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on the scalability of the albany felix first order Stokes Approximation ice sheet solver for large scale simulations of the greenland and antarctic ice sheets
International Conference on Conceptual Structures, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Steven PriceAbstract:We examine the scalability of the recently developed Albany/FELIX finite-element based code for the first-order Stokes momentum balance equations for ice flow. We focus our analysis on the performance of two possible preconditioners for the iterative solution of the sparse linear systems that arise from the discretization of the governing equations: (1) a preconditioner based on the incomplete LU (ILU) factorization, and (2) a recently-developed algebraic multigrid (AMG) preconditioner, constructed using the idea of semi-coarsening. A strong scalability study on a realistic, high resolution Greenland ice sheet problem reveals that, for a given number of processor cores, the AMG preconditioner results in faster linear solve times but the ILU preconditioner exhibits better scalability. A weak scalability study is performed on a realistic, moderate resolution Antarctic ice sheet problem, a substantial fraction of which contains floating ice shelves, making it fundamentally different from the Greenland ice sheet problem. Here, we show that as the problem size increases, the performance of the ILU preconditioner deteriorates whereas the AMG preconditioner maintains scalability. This is because the linear systems are extremely ill-conditioned in the presence of floating ice shelves, and the ill-conditioning has a greater negative effect on the ILU preconditioner than on the AMG preconditioner.
Jae-tack Jeong - One of the best experts on this subject based on the ideXlab platform.
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slow motion of a circular cylinder in a plane poiseuille flow in a microchannel
Physics of Fluids, 2014Co-Authors: Jae-tack Jeong, Chulsoo JangAbstract:The slow motion of a circular cylinder in a plane Poiseuille flow in a microchannel is analyzed for a wide range of cylinder radii and positions across the channel. The cylinder translates parallel to the channel walls and rotates about its axis. The Stokes Approximation is used and the problem is solved analytically using the Papkovich-Fadle eigenfunction expansion and the least-squares method. The stream function and the pressure distribution of the flow field are obtained as results. The force and moment exerted on the cylinder, and the pressure change far from the cylinder, are calculated and shown as functions of the size and location of the cylinder. The results confirm some reciprocal relations exactly. In particular, the translational and rotational velocities of the drifting cylinder in the existing Poiseuille flow are determined. The induced pressure change, when the cylinder drifts in the Poiseuille flow, is also calculated. Some typical streamline patterns, depending on the size and location of the cylinder, are shown and discussed. When the cylinder translates and/or rotates in the channel blocked at infinity, a series of Moffatt eddies appears far from the cylinder in the channel, as expected.
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free surface deformation due to a source and a sink of equal strength in Stokes flow
European Journal of Mechanics B-fluids, 2009Co-Authors: Jae-tack JeongAbstract:Two-dimensional Stokes flow due to a source and a sink of equal strength below the free surface is analyzed and free surface shape and cusp formation are discussed. The source-sink pair below the free surface are aligned vertical to the free surface. In the analysis, the Stokes' Approximation is used and surface tension effects are included, but gravity is neglected. The solution is obtained by using conformal mapping and complex function theory. From the solution, typical free surface shapes are shown and formation of a cusp on the free surface is discussed. As the capillary number increases, the converging free surface shape becomes singular and tends to form a cusp for sufficiently large capillary number. Typically, streamline patterns for some capillary numbers are also shown. As the capillary number vanishes, the solution is reduced to the linearized potential flow solution.
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Slip boundary condition on an idealized porous wall
Physics of Fluids, 2001Co-Authors: Jae-tack JeongAbstract:Slip boundary condition on a porous wall is investigated by considering a viscous flow near an idealized porous wall based on the Stokes’ Approximation. The idealized porous wall is composed of a large number of parallel and equidistant thin semi-infinite plates. The flow is assumed to be a simple shear flow far from the plates and stagnant deep inside the channels of the plates. The slip velocity on the idealized porous wall is calculated by solving a Wiener–Hopf equation. From the streamline patterns shown, it is found that Moffatt’s infinite sequence of viscous eddies developed between the two adjacent plates. Pressure and shear stress distributions on the plates are shown and local flow near the edge of the plate is discussed. Laminar shear flow at the farfield unidirectional along the edges of the plates is also considered.
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two dimensional stagnation flow around a vertical plate above a plane wall
Physics of Fluids, 2000Co-Authors: Jae-tack JeongAbstract:Two-dimensional slow viscous stagnation flow around a vertical plate above a plane wall is investigated based on the Stokes Approximation. An exact formal expression of the stream function is obtained by use of the three-part Wiener–Hopf technique. From the formal expression obtained, the streamline patterns around the plate are shown and the force exerted on the plate is calculated. The stress distributions on the boundaries are also calculated. By examining the limiting case of very small distance between the wall and the plate, the formation of the Moffatt’s viscous eddies near the corner is explained.
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two dimensional slow stagnation flow around a vertical plate on a plane wall
Journal of the Physical Society of Japan, 1994Co-Authors: Jae-tack JeongAbstract:Two-dimensional slow viscous stagnation flow around a vertical plate on a plane wall is investigated based on the Stokes Approximation. An exact formal expression of the stream function is obtained by use of the Wiener-Hopf technique. From the formal expression obtained, the streamline patterns around the plate are shown and the force exerted on the plate is calculated. The flows near the corner and the leading edge of the plate are also discussed. By examining more general stagnation flows toward the plane wall, the procedure how a viscous corner eddy merges into the main flow is explained.
Mauro Perego - One of the best experts on this subject based on the ideXlab platform.
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albany felix a parallel scalable and robust finite element first order Stokes Approximation ice sheet solver built for advanced analysis
Geoscientific Model Development, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Stephen PriceAbstract:Abstract. This paper describes a new parallel, scalable and robust finite element based solver for the first-order Stokes momentum balance equations for ice flow. The solver, known as Albany/FELIX, is constructed using the component-based approach to building application codes, in which mature, modular libraries developed as a part of the Trilinos project are combined using abstract interfaces and template-based generic programming, resulting in a final code with access to dozens of algorithmic and advanced analysis capabilities. Following an overview of the relevant partial differential equations and boundary conditions, the numerical methods chosen to discretize the ice flow equations are described, along with their implementation. The results of several verification studies of the model accuracy are presented using (1) new test cases for simplified two-dimensional (2-D) versions of the governing equations derived using the method of manufactured solutions, and (2) canonical ice sheet modeling benchmarks. Model accuracy and convergence with respect to mesh resolution are then studied on problems involving a realistic Greenland ice sheet geometry discretized using hexahedral and tetrahedral meshes. Also explored as a part of this study is the effect of vertical mesh resolution on the solution accuracy and solver performance. The robustness and scalability of our solver on these problems is demonstrated. Lastly, we show that good scalability can be achieved by preconditioning the iterative linear solver using a new algebraic multilevel preconditioner, constructed based on the idea of semi-coarsening.
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on the scalability of the albany felix first order Stokes Approximation ice sheet solver for large scale simulations of the greenland and antarctic ice sheets
International Conference on Conceptual Structures, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Steven PriceAbstract:We examine the scalability of the recently developed Albany/FELIX finite-element based code for the first-order Stokes momentum balance equations for ice flow. We focus our analysis on the performance of two possible preconditioners for the iterative solution of the sparse linear systems that arise from the discretization of the governing equations: (1) a preconditioner based on the incomplete LU (ILU) factorization, and (2) a recently-developed algebraic multigrid (AMG) preconditioner, constructed using the idea of semi-coarsening. A strong scalability study on a realistic, high resolution Greenland ice sheet problem reveals that, for a given number of processor cores, the AMG preconditioner results in faster linear solve times but the ILU preconditioner exhibits better scalability. A weak scalability study is performed on a realistic, moderate resolution Antarctic ice sheet problem, a substantial fraction of which contains floating ice shelves, making it fundamentally different from the Greenland ice sheet problem. Here, we show that as the problem size increases, the performance of the ILU preconditioner deteriorates whereas the AMG preconditioner maintains scalability. This is because the linear systems are extremely ill-conditioned in the presence of floating ice shelves, and the ill-conditioning has a greater negative effect on the ILU preconditioner than on the AMG preconditioner.
Raymond S Tuminaro - One of the best experts on this subject based on the ideXlab platform.
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albany felix a parallel scalable and robust finite element first order Stokes Approximation ice sheet solver built for advanced analysis
Geoscientific Model Development, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Stephen PriceAbstract:Abstract. This paper describes a new parallel, scalable and robust finite element based solver for the first-order Stokes momentum balance equations for ice flow. The solver, known as Albany/FELIX, is constructed using the component-based approach to building application codes, in which mature, modular libraries developed as a part of the Trilinos project are combined using abstract interfaces and template-based generic programming, resulting in a final code with access to dozens of algorithmic and advanced analysis capabilities. Following an overview of the relevant partial differential equations and boundary conditions, the numerical methods chosen to discretize the ice flow equations are described, along with their implementation. The results of several verification studies of the model accuracy are presented using (1) new test cases for simplified two-dimensional (2-D) versions of the governing equations derived using the method of manufactured solutions, and (2) canonical ice sheet modeling benchmarks. Model accuracy and convergence with respect to mesh resolution are then studied on problems involving a realistic Greenland ice sheet geometry discretized using hexahedral and tetrahedral meshes. Also explored as a part of this study is the effect of vertical mesh resolution on the solution accuracy and solver performance. The robustness and scalability of our solver on these problems is demonstrated. Lastly, we show that good scalability can be achieved by preconditioning the iterative linear solver using a new algebraic multilevel preconditioner, constructed based on the idea of semi-coarsening.
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on the scalability of the albany felix first order Stokes Approximation ice sheet solver for large scale simulations of the greenland and antarctic ice sheets
International Conference on Conceptual Structures, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Steven PriceAbstract:We examine the scalability of the recently developed Albany/FELIX finite-element based code for the first-order Stokes momentum balance equations for ice flow. We focus our analysis on the performance of two possible preconditioners for the iterative solution of the sparse linear systems that arise from the discretization of the governing equations: (1) a preconditioner based on the incomplete LU (ILU) factorization, and (2) a recently-developed algebraic multigrid (AMG) preconditioner, constructed using the idea of semi-coarsening. A strong scalability study on a realistic, high resolution Greenland ice sheet problem reveals that, for a given number of processor cores, the AMG preconditioner results in faster linear solve times but the ILU preconditioner exhibits better scalability. A weak scalability study is performed on a realistic, moderate resolution Antarctic ice sheet problem, a substantial fraction of which contains floating ice shelves, making it fundamentally different from the Greenland ice sheet problem. Here, we show that as the problem size increases, the performance of the ILU preconditioner deteriorates whereas the AMG preconditioner maintains scalability. This is because the linear systems are extremely ill-conditioned in the presence of floating ice shelves, and the ill-conditioning has a greater negative effect on the ILU preconditioner than on the AMG preconditioner.
Andrew G Salinger - One of the best experts on this subject based on the ideXlab platform.
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albany felix a parallel scalable and robust finite element first order Stokes Approximation ice sheet solver built for advanced analysis
Geoscientific Model Development, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Stephen PriceAbstract:Abstract. This paper describes a new parallel, scalable and robust finite element based solver for the first-order Stokes momentum balance equations for ice flow. The solver, known as Albany/FELIX, is constructed using the component-based approach to building application codes, in which mature, modular libraries developed as a part of the Trilinos project are combined using abstract interfaces and template-based generic programming, resulting in a final code with access to dozens of algorithmic and advanced analysis capabilities. Following an overview of the relevant partial differential equations and boundary conditions, the numerical methods chosen to discretize the ice flow equations are described, along with their implementation. The results of several verification studies of the model accuracy are presented using (1) new test cases for simplified two-dimensional (2-D) versions of the governing equations derived using the method of manufactured solutions, and (2) canonical ice sheet modeling benchmarks. Model accuracy and convergence with respect to mesh resolution are then studied on problems involving a realistic Greenland ice sheet geometry discretized using hexahedral and tetrahedral meshes. Also explored as a part of this study is the effect of vertical mesh resolution on the solution accuracy and solver performance. The robustness and scalability of our solver on these problems is demonstrated. Lastly, we show that good scalability can be achieved by preconditioning the iterative linear solver using a new algebraic multilevel preconditioner, constructed based on the idea of semi-coarsening.
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on the scalability of the albany felix first order Stokes Approximation ice sheet solver for large scale simulations of the greenland and antarctic ice sheets
International Conference on Conceptual Structures, 2015Co-Authors: Irina Kalashnikova Tezaur, Mauro Perego, Andrew G Salinger, Raymond S Tuminaro, Steven PriceAbstract:We examine the scalability of the recently developed Albany/FELIX finite-element based code for the first-order Stokes momentum balance equations for ice flow. We focus our analysis on the performance of two possible preconditioners for the iterative solution of the sparse linear systems that arise from the discretization of the governing equations: (1) a preconditioner based on the incomplete LU (ILU) factorization, and (2) a recently-developed algebraic multigrid (AMG) preconditioner, constructed using the idea of semi-coarsening. A strong scalability study on a realistic, high resolution Greenland ice sheet problem reveals that, for a given number of processor cores, the AMG preconditioner results in faster linear solve times but the ILU preconditioner exhibits better scalability. A weak scalability study is performed on a realistic, moderate resolution Antarctic ice sheet problem, a substantial fraction of which contains floating ice shelves, making it fundamentally different from the Greenland ice sheet problem. Here, we show that as the problem size increases, the performance of the ILU preconditioner deteriorates whereas the AMG preconditioner maintains scalability. This is because the linear systems are extremely ill-conditioned in the presence of floating ice shelves, and the ill-conditioning has a greater negative effect on the ILU preconditioner than on the AMG preconditioner.