LARGE-EDDY SIMULATION OF TEMPORALLY DEVELOPING JUNCTURE FLOWS

Large eddy simulation (LES) results are reported for temporally develo ping solid-solid and solid-rigid-lid juncture flows. A MacCormack-type scheme that is second-order in time, and fourth-order in space for th e convective terms and second-order in space for the viscous terms, is used. The simulations are obtained for a low subsonic Mach number. Th e subgrid-scale stresses (SGS) are modeled using the dynamic modeling procedure. The turbulent flow field generated on a flat-plate boundary layer is used to initialize the juncture flow simulations. The result s of the flat-plate boundary layer simulations are validated with expe rimental and direct numerical simulations (DNS) data. In juncture flow simulations, the presence of an adjacent solid-wall/rigid-lid boundar y altered the mean and the turbulent field, setting up gradients in th e anisotropy of normal Reynolds stresses resulting in the formation of turbulence-induced secondary vortices. The relative size of these sec ondary vortices and the distribution of mean and turbulent quantities are in qualitative agreement with the experimental observations for th e solid-solid juncture. The overall distribution of the mean and turbu lence quantities showed close resemblance between the solid-solid and the solid-rigid-lid junctures; except for the absence of a second vort ical region near the rigid-lid boundary. In agreement with the experim ental observations, it was found that the normalized anisotropy term e xhibited similarity when plotted against the distance from the boundar y, regardless of the type of boundary, i.e. solid-wall or rigid-lid. T he turbulent kinetic energy increased near the rigid-lid boundary. Whi le the surface normal velocity fluctuations decreased to zero at the r igid-lid boundary, the other two velocity components showed an increas e in their energy, which is also consistent with the experimental obse rvations. (C) 1998 John Wiley & Sons, Ltd.