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Multigrid methods for flow transition in three-dimensional boundary layers with surface roughnessThe 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.
Document ID
19940014370
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Liu, Chaoqun (Ecodynamics Research Associates, Inc. Denver, CO, United States)
Liu, Zhining (Ecodynamics Research Associates, Inc. Denver, CO, United States)
Mccormick, Steve (Ecodynamics Research Associates, Inc. Denver, CO, United States)
Date Acquired
September 6, 2013
Publication Date
September 1, 1993
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
NASA-CR-4540
NAS 1.26:4540
Accession Number
94N18843
Funding Number(s)
CONTRACT_GRANT: NAS1-19312
PROJECT: RTOP 505-59-50-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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