Ground effects on separated laminar flows past an inclined flat plate

• Published in: Theoretical and computational fluid dynamics 2017-04, Vol.31 (2), p.127-136
• Main Authors: Li, Zhen, Lan, Chuanjin, Jia, Laibing, Ma, Yanbao
• Format: Article
• Language: English
• Subjects: Classical and Continuum Physics; Computational fluid dynamics; Computational Science and Engineering; Engineering; Engineering Fluid Dynamics; Flat plates; Fluid dynamics; Grounds; Laminar flow; Mathematical models; Numerical analysis; Original Article; Shear stress; Steady flow; Viscosity; Vortices; Walls
• ISSN: 0935-4964; 1432-2250
• DOI: 10.1007/s00162-016-0410-0

The appearance of a ground surface can play an important role in the flow structures for the flows past a flat plate. We conduct two-dimensional numerical simulations on viscous flows past a flat plate inclined at an angle of attack of 20 ∘ with ground effects using a finite-volume method. Results show that the effects on the separated flow from the ground are highly dependent on the gap ( G ) between the plate and the ground. As the gap decreases, the strength of vortices generated from the trailing edge is restrained, which is consistent with experimental observations. Further decrease in the gap even eliminates the vortex shedding and yields a steady flow. It is also found that the flow between the gap can either be accelerated at large gap ratios ( G / L > 1 , G is the gap, L is the plate length), or be decelerated at small gap ratios ( G / L < 1 ). Furthermore, the numerical results show that the wake flow behind the plate can significantly change the distribution of surface shear stress on the ground. Specifically, the mean shear stress on the ground in the downstream region at a gap ratio G / L = 2.0 is one order of magnitude larger than that at a small gap ratio G / L = 0.3 , and the length of the downstream region where the shear stress can be effectively changed is much larger than the plate length, which provides a guideline to manipulate the ground wall surface shear stress using an inclined plate in the vicinity of the wall.