AN ANALYSIS OF ROTATING SHEAR-FLOW USING LINEAR-THEORY AND DNS AND LES RESULTS

The development of turbulence is investigated in the presence of a mea n plane shear flow (rate S) rotating with angular velocity vector (rat e SZ) perpendicular to its plane. An important motivation was generali zing the work by Lee, Kim & Moin (1990) to rotating shear flow, in par ticular detailed comparisons of homogeneous rapid distort:ion theory ( RDT) results and the databases of homogeneous and channel flow direct numerical simulations (DNS). Linear analysis and related RDT are used starting fi om the linearized equations governing the fluctuating velo city field. The parameterization based on the value of the Bradshaw-Ri chardson number B = R(1 + R) (with R = -2 Omega/S) is checked against complete linear solutions. Owing to the pressure fluctuation, the dyna mics is not governed entirely by the parameter B, and the subsequent b reaking of symmetry (between the R and -1 - R cases) is investigated. New;analytical solutions for the 'two-dimensional energy components' E -ij((l)) = E-ij(k(l) = 0, t) (i.e. the limits at k(l) = 0 of the one-d imensional energy spectral are calculated by inviscid and viscous RDT, for various ratios Omega/S and both streamwise l = 1 and spanwise I = 3 directions. Structure effects (streak-like tendencies, dimensionali ty) in rotating shear flow are discussed through these quantities and more conventional second-order statistics. In order to compare in a qu antitative way RDT solutions for single-point statistics with availabl e large-eddy simulation (LES) data (Bardina, Ferziger & Reynolds 1983) , an 'effective viscosity' model (following Townsend) is used, yieldin g an impressive agreement.