Experimental investigation of the large-scale velocity statistics in homogeneous turbulent shear flow

Abstract

Motivated by the numerical results of Isaza and Collins [“On the asymptotic behaviour of large-scale turbulence in homogeneous shear flow,” J. Fluid Mech. (in press)], the sensitivity of the self-similar behavior of the large-scale velocity statistics in an homogeneous turbulent shear flow to the initial value of the shear parameter and Reynolds number is investigated in a wind tunnel. Using an active grid, the initial value of Reynolds number based on the Taylor microscale is varied over the range 100≤Rλ≤250. The shear is generated using screens of different solidities followed by a series of straightening channels [S. Garg and Z. Warhaft, Phys. Fluids 10, 662 (1998)], allowing us to vary the initial value of the shear parameter over the modest range 6≤S0*≤12. We find that the longtime behavior of the shear parameter depends on its initial value over the nondimensional time interval 5≤St≤25, but is less sensitive to the initial value of the Reynolds number. The ratio of the turbulent kinetic energy produ...