Study of Flow Characteristics around a NearWall Circular Cylinder Subjected to a Steady CrossFlow

Mohammad Amin Salehi ^{} , Said Mazaheri , Mohammad Hossein Kazeminezhad 
PhD student student 

Abstract: (223 Views) 
Threedimensional RANS simulations are employed numerically to study flow characteristics around a nearwall circular cylinder for varying gaptodiameter (G/D) ratios (Where G is the gap between the cylinder and the wall and D is the cylinder diameter) and at Reynolds numbers from 100 to 3900. Pressure distribution around the circular cylinder, base pressure magnitude, separation and stagnation angles, force coefficients and Strouhal numbers were calculated and compared for all of the cases. Inception of vortex shedding can be seen when a sudden decrease in the maximum of positive pressure coefficient occurs. Vortex shedding mechanism and possibility of suppression further investigated via comparison of swirling strength in upper and lower vortex regions through parameter Λ, which signifies vortical activity and balance with respect to the wake centerline and also the flow type parameter, λ, representing the extensional strain dominance in the wake flow and gap flow. Vortex shedding suppression observed for the cases with the high unbalance vorticity content in the vortex regions, namely for Λ ≥ 2. 

Keywords: pressure distribution, force coefficients, separation angle, stagnation angle, vortex shedding suppression 

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Type of Study: Research 
Subject:
Marine Hydrodynamics Received: 2018/01/7  Accepted: 2018/03/6  Published: 2018/05/5





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