Abstract
We investigated the spatial structures of wall turbulence predicted with an extended subgrid scale (SGS) model for large eddy simulations (LES) of non-Newtonian viscos fluid such as the power-law model fluid to validate reliability of the prediction in the instantaneous flow field by comparing the results of a direct numerical simulation (DNS). The extended SGS model was proposed according to the modulation of the spatial scale of coherent structures in turbulent flow of non-Newtonian viscous fluid. In the simulation of non-Newtonian viscous fluid with the traditional SGS model, quasi-streamwise vortices could not be observed in the flow field and the spanwise spacing of velocity streaks increased obviously. To the contrary in the simulation with the extended SGS model, the characteristics of the instantaneous turbulence structures corresponded with those of DNS. Consequently, it was proved that the extended SGS model could be used to predict not only the mean velocity profile but also instantaneous structures of wall turbulence.
