Nusselt Number,force And Strouhal Number Variations From Square To Circular Cylinders At A Low Reynolds Number

This paper mainly studies the effect of the incidence angles of incoming flow()and corner curvature ratios(r/R)on the flow structure and heat transfer around a cylinder.The incidence angle of incoming flow(?)includes 0°,3°,5°,7°,10°,15°,20°,30°,37°,45° and the corner curvature ratio(r/R)includes 0(square cylinder),0.1,0.25,0.5,0.75,1.0(circular cylinder),where r is the corner radius and R is the circular cylinder radius.The simulation about flow character and heat transfer are proceeded at Re = 150 and Pr = 0.7.The project mainly researches the effect of incidence angle of incoming flow and corner curvature ratio on flow structure and heat transfer around the cylinder by using the CFD simulation calculation.It includes forces(CD,CDf,CLf),non-dimensional vortex shedding frequency(St)and non-dimensional heat transfer coefficient(Nu).We have obtained four flow patterns according to different flow structures.A detailed analysis of mean pressure coefficient(CP),fluctuating pressure coefficient(CPf),wake structure(w/D and Lf/D),Nusselt number(Nu)and wall shear stress(?W)distribution in each flow pattern.It can be observed that,the rounded corners can reduce the dynamic drag of the cylinder,the minimum occurs at ? = 5°,r/R = 0.75,it decreases about 35% compared to the maximum value.And the heat transfer of the cylinder increases with increasing incoming flow incidence angle.All in all,rounded corners of the cylinder can effectively reduce the drag and the increasing incoming flow incidence angle is advantage to heat transfer from the cylinder.Keeping balance of these two norms,the best one is flow pattern 4,where the drag is small and heat transfer is large.