Note on a Parametric Relation for Separating Flow over a Rough Hill |
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| Authors: | J B R Loureiro A P Silva Freire |
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| Institution: | 1.Programa de Engenharia Mecanica (COPPE/UFRJ),Universidade Federal do Rio de Janeiro,Rio de Janeiro,Brazil;2.Divis?o de Metrologia Científica,Instituto Nacional de Metrologia (INMETRO),Rio de Janeiro,Brazil |
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| Abstract: | A parametrization method used to account for the effects of flow separation and wall roughness on the lower boundary condition
for turbulent boundary layers is investigated against direct numerical simulation and laser Doppler anemometry data. The numerical
simulation represents flow over a smooth, flat surface with a prescribed external adverse pressure gradient. The water-channel
experiments cover flow over smooth and rough hills for two specified Reynolds numbers. Global optimization algorithms based
on four different direct search methods are used to assess the parametrization function, C, in terms of local mean velocity profiles and the parametrization parameters u
* (friction velocity), ∂
x
p (local pressure gradient), z
0 (effective roughness) and d (zero-plane displacement). The study investigates regions of attached and reversed flows, and forty-two velocity profiles
are compared with the proposed expression for the function C, including two profiles that satisfy the solution of Stratford. |
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| Keywords: | Hill flow Lower boundary condition Roughness Separation |
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