Flow Characteristics Behind Rectangular Cylinder Placed Near a Wall

Abstract

Three-dimensional unsteady flow over a bluff body located parallel to a wall, kept at different gap height from the wall, has been studied numerically. The bluff body considered is a rectangular cylinder with two different aspect ratios, B/D = 1 and B/D = 2, where B and D are the width and height of the cylinder, respectively. The flow is considered as a laminar flow, and the Reynolds number based on the height of the cylinder cross section and oncoming reference velocity is 450. Numerical study is carried out by varying the distance of the cylinder from the wall, and the development of the vortex shedding phenomenon under the influence of the wall is investigated. From previous experiments, it is observed that as the distance between the wall and the cylinder decreases, the wake behind the cylinder becomes stationary and the vortex shedding is suppressed. The present numerical study confirms a similar trend. Periodic activity in the downstream of the flow is disturbed completely with decreasing gap between the wall and the cylinder.

Notes

^a St, Strohaul number; C _l and C _d , mean lift and drag coefficients; C _{l rms} and C _{d rms}, root-mean-square of lift and drag coefficients. G21 = 183 × 133 × 21, spanlength = 4D, G28 = 183 × 133 × 28, spanlength = 4D, G41 = 183 × 133 × 41, spanlength = 8D, G54 = 183 × 54 × 133, spanlength = 8D.