The Effects of Aspect Ratio and End Condition on the Control of Free Shear Layers Development and Force Coefficients for Flow Past Four Cylinders in the In-line Square Configuration

The effects of aspect ratio and end condition on the control of the development of free shear layers and the force coefficients of cylinders for flows around four cylinders at critical spacing ratio

L/D

=3.5 in the in-line square configuration have been investigated numerically. The study demonstrated that the aspect ratio and end condition of the four cylinders produce a strong influence on the free shear layer development from the upstream cylinder and hence the pressure fields and force characteristics of the cylinders. The mean pressure and fluctuating pressure increase towards the mid-span of the cylinders. The development of free shear layers, the mean and fluctuating pressure as well as the force coefficients are critically affected by the cylinder aspect ratio in the range of

H/D

from 15 to 16.