New Two-Equation Closure for Rough-Wall Turbulent Flows Using the Brinkman Equation

AIAA Journal ◽  
2009 ◽  
Vol 47 (2) ◽  
pp. 386-398 ◽  
Author(s):  
Meng-Huang Lu ◽  
William W. Liou
Keyword(s):  
Turbulent Flows ◽  
Rough Wall ◽  
Brinkman Equation

scholarly journals Data-driven prediction of the equivalent sand-grain height in rough-wall turbulent flows

2021 ◽  
Vol 912 ◽  
Author(s):  
Mostafa Aghaei Jouybari ◽  
Junlin Yuan ◽  
Giles J. Brereton ◽  
Michael S. Murillo
Keyword(s):  
Turbulent Flows ◽  
Rough Wall ◽  
Data Driven

Abstract

Rough-wall layer modeling using the Brinkman equation

2009 ◽  
Vol 10 ◽  
pp. N16 ◽  
Author(s):  
William W. Liou ◽  
Meng-Huang Lu
Keyword(s):  
Wall Layer ◽  
Rough Wall ◽  
Brinkman Equation

scholarly journals Turbulent flow over transitionally rough surfaces with varying roughness densities

2016 ◽  
Vol 804 ◽  
pp. 130-161 ◽  
Author(s):  
M. MacDonald ◽  
L. Chan ◽  
D. Chung ◽  
N. Hutchins ◽  
A. Ooi
Keyword(s):  
Turbulent Flows ◽  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Turbulent Energy ◽  
Rough Wall ◽  
Momentum Balance ◽  
Wall Flows ◽  
Roughness Elements ◽  
The Difference ◽  
Near Wall

We investigate rough-wall turbulent flows through direct numerical simulations of flow over three-dimensional transitionally rough sinusoidal surfaces. The roughness Reynolds number is fixed at $k^{+}=10$, where $k$ is the sinusoidal semi-amplitude, and the sinusoidal wavelength is varied, resulting in the roughness solidity $\unicode[STIX]{x1D6EC}$ (frontal area divided by plan area) ranging from 0.05 to 0.54. The high cost of resolving both the flow around the dense roughness elements and the bulk flow is circumvented by the use of the minimal-span channel technique, recently demonstrated by Chung et al. (J. Fluid Mech., vol. 773, 2015, pp. 418–431) to accurately determine the Hama roughness function, $\unicode[STIX]{x0394}U^{+}$. Good agreement of the second-order statistics in the near-wall roughness-affected region between minimal- and full-span rough-wall channels is observed. In the sparse regime of roughness ($\unicode[STIX]{x1D6EC}\lesssim 0.15$) the roughness function increases with increasing solidity, while in the dense regime the roughness function decreases with increasing solidity. It was found that the dense regime begins when $\unicode[STIX]{x1D6EC}\gtrsim 0.15{-}0.18$, in agreement with the literature. A model is proposed for the limit of $\unicode[STIX]{x1D6EC}\rightarrow \infty$, which is a smooth wall located at the crest of the roughness elements. This model assists with interpreting the asymptotic behaviour of the roughness, and the rough-wall data presented in this paper show that the near-wall flow is tending towards this modelled limit. The peak streamwise turbulence intensity, which is associated with the turbulent near-wall cycle, is seen to move further away from the wall with increasing solidity. In the sparse regime, increasing $\unicode[STIX]{x1D6EC}$ reduces the streamwise turbulent energy associated with the near-wall cycle, while increasing $\unicode[STIX]{x1D6EC}$ in the dense regime increases turbulent energy. An analysis of the difference of the integrated mean momentum balance between smooth- and rough-wall flows reveals that the roughness function decreases in the dense regime due to a reduction in the Reynolds shear stress. This is predominantly due to the near-wall cycle being pushed away from the roughness elements, which leads to a reduction in turbulent energy in the region previously occupied by these events.

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