Reynolds number effects in the outer layer of the turbulent flow in a channel with rough walls

2005 ◽  
Vol 17 (6) ◽  
pp. 065101 ◽  
Author(s):  
Ole Martin Bakken ◽  
Per-Åge Krogstad ◽  
Alireza Ashrafian ◽  
Helge I. Andersson
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Outer Layer ◽  
Rough Walls ◽  
Reynolds Number Effects

scholarly journals Statistical Structure and Deviations from Equilibrium in Wavy Channel Turbulence

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 161 ◽  
Author(s):  
Saadbin Khan ◽  
Balaji Jayaraman
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Outer Layer ◽  
Strong Dependence ◽  
Surface Topology ◽  
Intermittent Flow ◽  
Turbulence Structure ◽  
Near Surface ◽  
Practical Applications ◽  
Major Interest

The structure of turbulent flow over non-flat surfaces is a topic of major interest in practical applications in both engineering and geophysical settings. A lot of work has been done in the fully rough regime at high Reynolds numbers where the effect on the outer layer turbulence structure and the resulting friction drag is well documented. It turns out that surface topology plays a significant role on the flow drag especially in the transitional roughness regime and therefore, is hard to characterize. Survey of literature shows that roughness function depends on the interaction of roughness height, flow Reynolds number, and topology shape. In addition, if the surface topology contains large enough scales then it can impact the outer layer dynamics and in turn modulate the total frictional force. Therefore, it is important to understand the mechanisms underlying drag increase from systematically varied surface undulations in order to better interpret quantifications based on mean statistics such as roughness function. In this study, we explore the mechanisms that modulate the turbulence structure over a two-dimensional (2D) sinusoidal wavy surface with a fixed amplitude, but varying slopes that are sufficiently small to generate only intermittent flow separation. To accomplish this, we perform a set of highly resolved direct numerical simulations (DNS) to model the turbulent flow between two infinitely wide 2D wavy plates at a friction Reynolds number, R e τ = 180 , which represents modest scale separation. We pursue two different but related flavors of analysis. The first one adopts a roughness characterization flavor of such wavy surfaces. The second one focuses on understanding the nonequilibrium near-surface turbulence structure and their impact on roughness characterization. Analysis of the different statistical quantifications show strong dependence on wave slope for the roughness function indicating drag increase due to enhanced turbulent stresses resulting from increased production of vertical velocity variance from the surface undulations.

scholarly journals Statistical Structure and Deviations from Equilibrium in Wavy Channel Turbulence

2019 ◽  
Author(s):  
Saadbin Khan ◽  
Balaji Jayaraman
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Outer Layer ◽  
Strong Dependence ◽  
Surface Topology ◽  
Turbulence Structure ◽  
Near Surface ◽  
Practical Applications ◽  
Flat Surfaces ◽  
Major Interest

The structure of turbulent flow over non-flat surfaces is a topic of major interest in practical applications in both engineering and geophysical settings. A lot of work has been done in the fully rough regime at high Reynolds numbers where the effect on the outer layer turbulence structure and the resulting friction drag is well documented. It turns out that surface topology plays a significant role on the flow drag especially in the transitional roughness regime and therefore, hard to characterize. Survey of literature shows that roughness function depends on the interaction of roughness height, flow Reynolds number and topology shape. In addition, if the surface topology contains large enough scales then it can impact the outer layer dynamics and in turn modulate the total frictional force. Therefore, it is important to understand the mechanisms underlying drag increase from systematically varied surface undulations in order to better interpret quantifications based on mean statistics such as roughness function. In this study, we explore the mechanisms that modulate the turbulence structure over a two-dimensional (2D) sinusoidal wavy surface with a fixed amplitude, but varying slope. To accomplish this, we model the turbulent flow between two infinitely wide 2D wavy plates at a friction Reynolds number, $Re_{\tau}=180$. We pursue two different but related flavors of analysis. The first one adopts a roughness characterization flavor of such wavy surfaces. The second one focuses on understanding the non-equilibrium near surface turbulence structure and their impact on roughness characterization. Analysis of the different statistical quantifications show strong dependence on wave slope for the roughness function indicating drag increase due to enhanced turbulent stresses resulting from increased production of vertical velocity variance from the surface undulations.

Constrained large-eddy simulation of turbulent flow over rough walls

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Wen Zhang ◽  
Minping Wan ◽  
Zhenhua Xia ◽  
Jianchun Wang ◽  
Xiyun Lu ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flow ◽  
Eddy Simulation ◽  
Rough Walls ◽  
Large Eddy

Numerical and Experimental Analysis of Turbulent Flow in Corrugated Pipes

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Henrique Stel ◽  
Rigoberto E. M. Morales ◽  
Admilson T. Franco ◽  
Silvio L. M. Junqueira ◽  
Raul H. Erthal ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Velocity Magnitude ◽  
Geometric Configurations ◽  
Corrugated Surfaces ◽  
Friction Factors

This article describes a numerical and experimental investigation of turbulent flow in pipes with periodic “d-type” corrugations. Four geometric configurations of d-type corrugated surfaces with different groove heights and lengths are evaluated, and calculations for Reynolds numbers ranging from 5000 to 100,000 are performed. The numerical analysis is carried out using computational fluid dynamics, and two turbulence models are considered: the two-equation, low-Reynolds-number Chen–Kim k-ε turbulence model, for which several flow properties such as friction factor, Reynolds stress, and turbulence kinetic energy are computed, and the algebraic LVEL model, used only to compute the friction factors and a velocity magnitude profile for comparison. An experimental loop is designed to perform pressure-drop measurements of turbulent water flow in corrugated pipes for the different geometric configurations. Pressure-drop values are correlated with the friction factor to validate the numerical results. These show that, in general, the magnitudes of all the flow quantities analyzed increase near the corrugated wall and that this increase tends to be more significant for higher Reynolds numbers as well as for larger grooves. According to previous studies, these results may be related to enhanced momentum transfer between the groove and core flow as the Reynolds number and groove length increase. Numerical friction factors for both the Chen–Kim k-ε and LVEL turbulence models show good agreement with the experimental measurements.

Reynolds Number Effects on Shock-Wave Turbulent Boundary-Layer Interactions

AIAA Journal ◽  
1977 ◽  
Vol 15 (8) ◽  
pp. 1152-1158 ◽  
Author(s):  
C. C. Horstman ◽  
G. S. Settles ◽  
I. E. Vas ◽  
S. M. Bogdonoff ◽  
C.M. Hung
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Reynolds Number Effects

scholarly journals High-Reynolds-number effects on turbulent scalings in compressible channel flow

PAMM ◽  
2015 ◽  
Vol 15 (1) ◽  
pp. 489-490
Author(s):  
Davide Modesti ◽  
Matteo Bernardini ◽  
Sergio Pirozzoli
Keyword(s):  
Reynolds Number ◽  
Channel Flow ◽  
High Reynolds Number ◽  
Reynolds Number Effects ◽  
High Reynolds
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