Experimental and Numerical Study for the Cross-flow around Four Cylinders in an In-line Square Configuration

The cross-flow around four cylinders in an in-line square configuration with the spacing ratio (L/ D) 1.5,2.5,3.5 and 5.0 have been investigated experimentally using Laser Doppler Anemometer (LDA) and Digital Particle Image Velocimetry (DPIV). The experiments were carried out in a closed-loop wind tunnel with Reynolds number 1.128x104 to 1.982x 104 . Mean velocity distributions are obtained by LDA. The full field instantaneous and averaged velocity and vorticity components are measured by DPIY. The present experimental study indicated that several distinct flow patterns exist. Distinct vortex shedding of the upstream cylinders was suppressed for L/ D < 3.5 at Re= 1.128x104 . The flow patterns are affected by the spacing ratio and Re. In order to capture the details of the 3-D vortices structures and obtain all the instantaneous physical information, 3-D numerical simulations of the cross-flow around the four cylinders in an in-line square configuration with the spacing ratio 1.5 and 3.5, and Re=1.50x 104 are carried out using large eddy simulation (LES). The numerical results are in good agreement with the experimental results. These results provided full field instantaneous information of the flow structures, velocity field and vorticity field of cross-flow around the four cylinders in an in-line square configuration