Effect of the aspect ratio on the velocity field of a straight open-channel flow
| Autor: | Ghassan Nasif, Ram Balachandar, A.-M. Shinneeb |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Fluid Flow and Transfer Processes
Physics Aspect ratio Turbulence Mechanical Engineering Flow (psychology) Computational Mechanics 02 engineering and technology Mechanics Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas Open-channel flow Physics::Fluid Dynamics Momentum 020303 mechanical engineering & transports 0203 mechanical engineering Reynolds shear stress Mechanics of Materials 0103 physical sciences Vector field Communication channel |
| Zdroj: | Physics of Fluids. 33:085110 |
| ISSN: | 1089-7666 1070-6631 |
| DOI: | 10.1063/5.0057343 |
| Popis: | This study investigates numerically the effect of the aspect ratio (AR) on the velocity field characteristics of the turbulent flow of a straight open-channel flow. Five aspect ratio cases (AR = channel width/flow depth) are investigated ranging from a narrow case of AR = 1 to a wide case of AR = 9. The transient three-dimensional Navier–Stokes equations were numerically solved using a finite-volume approach with an improved–delayed detached-eddy simulation turbulence model. The objective of this study is to enhance our understanding of the effect of AR on the formation of secondary currents in a channel flow. The results revealed the formation of a pair of counter-rotating recirculation zones near the bottom corners of the channel, whose axes are aligned with the main flow direction. Each pair consists of a mean recirculation zone that resides near the bed (bed recirculation zone), and another one that resides near the sidewall (side recirculation zone). The AR appears to significantly influence the size and strength of the recirculation zones. With decreasing the AR, the momentum transport by the streamwise-vertical Reynolds shear stress in the horizontal direction appears to be inhibited at higher vertical locations, the momentum transport by streamwise-transverse Reynolds shear stress is considerably enhanced, and the momentum transport by vertical-transverse Reynolds shear stress is slightly enhanced. |
| Databáze: | OpenAIRE |
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