Discrete-vortex simulation of a turbulent separation bubble

Abstract

The discrete-vortex model is applied to simulate the separation bubble over a two- dimensional blunt flat plate with finite thickness and right-angled corners, which is aligned parallel to a uniform approaching stream. This flow situation is chosen because, unlike most previous applications of the model, the separation bubble is supposed to be strongly affected by a nearby solid surface. The major objective of this paper is to examine to what extent the discrete-vortex model is effective for such a flow. A simple procedure is employed to represent the effect of viscosity near the solid surface; in particular, the no-slip condition on the solid surface. A reduction in the circulation of elemental vortices is introduced as a function of their ages in order to represent the three-dimensional deformation of vortex filaments, An experiment was also performed for comparison purposes.The calculation yielded reasonable predictions of the time-mean and r.m.s. values of the velocity and the surface-pressure fluctuations, together with correlations between their fluctuating components, over most of the separation bubble. The interrelation between instantaneous spatial variations of the surface-pressure and velocity fluctuations were also obtained. A comparison between the calculated and measured results suggests that, in the real flow, the three-dimensional deformation of vortex filaments will become more and more dominant as the reattachment point is approached.

Application of Displacement Height and Surface Roughness Length to Determination Boundary Layer Development Length over Stepped Spillway

“…7 and 9 in Chen [41], where x = 1.1, 2.1 and 3.6 cm represent the linear distance from the concave of step to the section respectively. At x = 1.1 and 2.1 cm, the measurements are within the shadow of the step, which is a notoriously difficult location to simulate flow velocity [50]. The simulated velocities are in agreement with the measurements.…”

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