Direct Numerical Simulations of Turbulent Channel Flows with Moving Wall

Abstract

Direct numerical simulations of turbulent channel flows with moving spanwise wall is performed in this paper. The aim of this work is to show what influences can be caused in turbulent channel flow by spanwise moving wall, that introduces a new characteristic velocity. Figure 1 shows the flow geometry and the coordinate system. The DNS was performed using the standard spectral method. Three cases with the spanwise wall velocity W=0, U m and 2U m are simulated at constant flow rate, here U m is the mean stream velocity. The necessary parameters for DNS are as follows: Re m = Umδ/v =2 800 (Re τ0 = uτ0δ/v≈180), the computational domain is 4πδ, 2δ and 2πδ for the streamwise (x), normal (y) and spanwise (z) directions, respectively, and the grid resolution is 128x129x128. The results show that spanwise moving wall induce the skin friction increasing. The second-order turbulence statistics such as root-mean-square velocity fluctuations, Reynolds shear stress and root-mean-square vorticity fluctuations are substantial increase with spanwise velocity increasing. It is also observed that the root-mean-square velocity fluctuations become more even across the channel with spanwise velocity increasing. Open image in new window Figure 1 Flow geometry and coordinate system Open image in new window Figure 2 Mean streamwise velocity profiles