Experimental and numerical investigation of a disc-attached cylinder near a wall

Abstract

An experimental and numerical study is carried out to investigate the flow up- and downstream of a disc-attached cylinder near a wall with a Reynolds number of Re=U0d/ν=5.4⋅104 (U0 is the mean upstream flow velocity, d is the diameter of the cylinder, and ν is the kinematic viscosity). Laser Doppler Velocimetry measurements were conducted to obtain statistical flow parameters such as the mean velocity and turbulent kinetic energy. The experimental results show that the mean flow can be characterized as two-dimensional at a transverse distance of more than d away from the disc. Furthermore, it is shown that the effect of the disc and the cylinder fades away downstream. Analysis of a power spectrum of the vertical velocity fluctuations shows that vortex shedding is disturbed downstream of the disc. The numerical simulation is performed using a Reynolds-Averaged Navier–Stokes model. The turbulent kinetic energy and mean velocities are well-predicted by the numerical model. An increase in the peak amplitudes of the power spectra obtained from the vertical velocity fluctuations is found at a transverse distance of 3.75d from the centerline of the disc for both the experimental and numerical study, caused by vortices being transported by a transverse flow related to the disc.