Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723219436
Category :
Languages : en
Pages : 152
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The efficient multilevel adaptive method has been successfully applied to perform direct numerical simulations (DNS) of flow transition in 3-D channels and 3-D boundary layers with 2-D and 3-D isolated and distributed roughness in a curvilinear coordinate system. A fourth-order finite difference technique on stretched and staggered grids, a fully-implicit time marching scheme, a semi-coarsening multigrid method associated with line distributive relaxation scheme, and an improved outflow boundary-condition treatment, which needs only a very short buffer domain to damp all order-one wave reflections, are developed. These approaches make the multigrid DNS code very accurate and efficient. This allows us not only to be able to do spatial DNS for the 3-D channel and flat plate at low computational costs, but also to do spatial DNS for transition in the 3-D boundary layer with 3-D single and multiple roughness elements, which would have extremely high computational costs with conventional methods. Numerical results show good agreement with the linear stability theory, the secondary instability theory, and a number of laboratory experiments. The contribution of isolated and distributed roughness to transition is analyzed. Liu, Chaoqun and Liu, Zhining and Mccormick, Steve Unspecified Center BASE FLOW; BOUNDARY LAYER TRANSITION; CHANNEL FLOW; COMPUTATIONAL FLUID DYNAMICS; GRID GENERATION (MATHEMATICS); MULTIGRID METHODS; SURFACE ROUGHNESS; THREE DIMENSIONAL BOUNDARY LAYER; BOUNDARY CONDITIONS; FINITE DIFFERENCE THEORY; NAVIER-STOKES EQUATION; SPHERICAL COORDINATES; THREE DIMENSIONAL FLOW; TIME MARCHING; TWO DIMENSIONAL FLOW...
Author: Chaoqun Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 156
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Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 704
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Author:
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ISBN:
Category :
Languages : en
Pages : 40
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Author: Chaoqun Liu
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 44
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Category : Government publications
Languages : en
Pages :
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Author:
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ISBN:
Category : Government publications
Languages : en
Pages : 872
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722391799
Category :
Languages : en
Pages : 42
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A new technology was developed in this study which provides a successful numerical simulation of the whole process of flow transition in 3-D boundary layers, including linear growth, secondary instability, breakdown, and transition at relatively low CPU cost. Most other spatial numerical simulations require high CPU cost and blow up at the stage of flow breakdown. A fourth-order finite difference scheme on stretched and staggered grids, a fully implicit time marching technique, a semi-coarsening multigrid based on the so-called approximate line-box relaxation, and a buffer domain for the outflow boundary conditions were all used for high-order accuracy, good stability, and fast convergence. A new fine-coarse-fine grid mapping technique was developed to keep the code running after the laminar flow breaks down. The computational results are in good agreement with linear stability theory, secondary instability theory, and some experiments. The cost for a typical case with 162 x 34 x 34 grid is around 2 CRAY-YMP CPU hours for 10 T-S periods. Liu, Chaoqun and Liu, Zhining Glenn Research Center NAS1-10312; NCC3-233; RTOP 505-90-5K...
Author: Yifei Yu
Publisher: Springer Nature
ISBN: 3031536703
Category :
Languages : en
Pages : 201
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Author: Chaoqun Liu
Publisher:
ISBN:
Category : Eddies
Languages : en
Pages : 688
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