Large eddy simulations of confined turbulent wake flows

Abstract

The influence of confinement on turbulent obstacle-free wake is numerically investigated by means of large eddy simulations (LES). The numerical solver makes use of a multi-domain Fourier-Chebyshev spectral method and the LES capability is implemented through a spectral vanishing viscosity technique. The geometry is channel like and the transverse direction is homogeneous. A top hat like velocity profile is assumed at the inlet and no slip conditions are considered at the confining walls. Prescribing the velocity ratio, defined as the ratio of the velocity gap to the mean velocity, we study the influence of confinement on such flows at the Reynolds number Re = 5000. Several quantities are analyzed, as one-dimensional velocity spectra, third-order structure function, turbulent kinetic energy and its dissipation rate. It turns out that for obstacle-free wakes confinement increases the intensity of turbulence and its three-dimensional feature.