Turbulence structure and transport mechanism at the free surface in an open channel flow

1982 ◽  
Vol 25 (4) ◽  
pp. 513-521 ◽  
Author(s):  
Komori Satoru ◽  
Ueda Hiromasa ◽  
Ogino Fumimaru ◽  
Mizushina Tokuro
Keyword(s):  
Free Surface ◽  
Channel Flow ◽  
Transport Mechanism ◽  
Open Channel ◽  
Open Channel Flow ◽  
Turbulence Structure

Interaction of surface waves with turbulence: direct numerical simulations of turbulent open-channel flow

1995 ◽  
Vol 286 ◽  
pp. 1-23 ◽  
Author(s):  
Vadim Borue ◽  
Steven A. Orszag ◽  
Ilya Staroselsky
Keyword(s):  
Free Surface ◽  
Numerical Simulations ◽  
Channel Flow ◽  
Gravity Waves ◽  
Open Channel ◽  
Open Channel Flow ◽  
Surface Region ◽  
Direct Numerical Simulations ◽  
Turbulence Production ◽  
Wind Sea

We report direct numerical simulations of incompressible unsteady open-channel flow. Two mechanisms of turbulence production are considered: shear at the bottom and externally imposed stress at the free surface. We concentrate upon the effects of mutual interaction of small-amplitude gravity waves with in-depth turbulence and statistical properties of the near-free-surface region. Extensions of our approach can be used to study turbulent mixing in the upper ocean and wind–sea interaction, and to provide diagnostics of bulk turbulence.

scholarly journals Turbulence structure of non-uniform rough open channel flow

2018 ◽  
Vol 40 ◽  
pp. 05039
Author(s):  
Priscilla Williams ◽  
Vesselina Roussinova ◽  
Ram Balachandar
Keyword(s):  
Pressure Gradient ◽  
Channel Flow ◽  
Friction Velocity ◽  
Open Channel ◽  
Open Channel Flow ◽  
Shear Stresses ◽  
Turbulence Structure ◽  
Mean Flow ◽  
Rough Bed ◽  
The Mean

This paper focuses on the turbulence structure in a non-uniform, gradually varied, sub-critical open channel flow (OCF) on a rough bed. The flow field is analysed under accelerating, near-uniform and decelerating conditions. Information for the flow and turbulence parameters was obtained at multiple sections and planes using two different techniques: two-component laser Doppler velocimetry (LDV) and particle image velocimetry (PIV). Different outer region velocity scaling methods were explored for evaluation of the local friction velocity. Analysis of the mean velocity profiles showed that the overlap layer exists for all flow cases. The outer layer of the decelerated velocity profile was strongly affected by the pressure gradient, where a large wake was noted. Due to the prevailing nature of the experimental setup it was found that the time-averaged flow quantities do not attained equilibrium conditions and the flow is spatially heterogeneous. The roughness generally increases the friction velocity and its effect was stronger than the effect of the pressure gradient. It was found that for the decelerated flow section over a rough bed, the mean flow and turbulence intensities were affected throughout the flow depth. The flow features presented in this study can be used to develop a model for simulating flow over a block ramp. The effect of the non-uniformity and roughness on turbulence intensities and Reynolds shear stresses was further investigated.

Turbulence structure in open channel flow with partially covered artificial emergent vegetation

2019 ◽  
Vol 573 ◽  
pp. 180-193 ◽  
Author(s):  
Wen-Xin Huai ◽  
Jiao Zhang ◽  
Wei-Jie Wang ◽  
Gabriel G. Katul
Keyword(s):  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Emergent Vegetation ◽  
Turbulence Structure

scholarly journals LES OF OPEN-CHANNEL FLOW WITH FREE-SURFACE FLUCTUATION

2002 ◽  
Vol 46 ◽  
pp. 373-378 ◽  
Author(s):  
Akihiko NAKAYAMA ◽  
Satoshi YOKOJIMA
Keyword(s):  
Free Surface ◽  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Surface Fluctuation

scholarly journals Free-surface flows with near-critical flow conditions

1996 ◽  
Vol 23 (6) ◽  
pp. 1272-1284 ◽  
Author(s):  
H. Chanson
Keyword(s):  
Free Surface ◽  
Channel Flow ◽  
Open Channel ◽  
Flow Instability ◽  
Open Channel Flow ◽  
Surface Characteristics ◽  
Free Surface Flows ◽  
Critical Flow ◽  
Flow Conditions ◽  
Weir Flow

Open channel flow situations with near-critical flow conditions are often characterized by the development of free-surface instabilities (i.e., undulations). The paper develops a review of several near-critical flow situations. Experimental results are compared with ideal-fluid flow calculations. The analysis is completed by a series of new experiments. The results indicate that, for Froude numbers slightly above unity, the free-surface characteristics are very similar. However, with increasing Froude numbers, distinctive flow patterns develop. Key words: open channel flow, critical flow conditions, free-surface undulations, flow instability, undular surge, undular broad-crested weir flow, culvert flow.

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