ABSTRAKT

Numerical experiments by Large-Eddy Simulation (LES) are performed on the turbulent flow and mixing of a passive scalar past a square cylinder. A Reynolds number of 21 400 is selected, matching available flow measurements from laser-doppler velocimetry (LDV), and the scalar released from a point source downstream of the cylinder. A comparative study of numerical results against LDV data is presented in order to validate the present LES methodology, where subgrid turbulent stresses are estimated via the WALE similarity mixed model coupled with newly developed constrained filtering operators of arbitrary order and scalar fluxes approximated via the Reynolds analogy. Time-averaged and phase-averaged statistics for the scalar field, including scalar variance and scalar flux components, are computed to examine further the role of coherent fluctuations associated with large-scale structures on the mixing process and to establish a database for turbulence models development and validation.