Numerical simulation of flow around finite-length wavy cylinders

Abstract:

To study the drag reduction and vibration suppression effect of finite-length wavy cylinder which has a fixed end and a free end, the finite-length wavy cylinder was calculated. First, large eddy simulation numerical model was adopted to calculate finite-length straight cylinder and 12 finite-length wavy cylinders with different combinations of wavelength and amplitude at Re=3 900. Then, after post-processing the results, the lift and drag coefficients of the finite-length wavy cylinders with different combinations were compared, and corresponding drag reduction and vibration suppression effect was analyzed. Finally, flow field analysis was carried out on the combination forms with better drag reduction and vibration suppression effect, and the mechanism of drag reduction and vibration suppression of finite-length wavy cylinder was studied. Results show that for the 12 kinds of wavy cylinders, most of the wavy cylinder forms could reduce the root mean square value of the lift coefficient, which could suppress the vibration, and the best combination form reduced the mean drag coefficient by 5.36%. The flow characteristics around finite-length straight cylinder were similar with those around finite-length wavy cylinder. While due to the existence of saddle and nodal surfaces of wavy cylinder, the fluid interacted in the direction of the cylinder, weakening the development of the vortex behind the cylinder, which reduced the drag reduction and vibration suppression effect. The research results can summarize the drag reduction and vibration suppression effect of finite-length wavy cylinders, which is helpful to investigate the drag reduction and vibration suppression mechanism of finite-length wavy cylinders.