2013 Volume 8 Issue 1 Pages 54-64
We performed direct numerical simulations (DNSs) of turbulent channel flow for surfactant solutions with the purpose in developing a modified large eddy simulation (LES) method based on the knowledge obtained from such DNSs that include drag reduction effects. Our results indicate that, by a variable viscosity-dependent normalization of the spatial scale, the profiles and the peak positions of the turbulence statistics approximate those of a Newtonian fluid. The implication is that by such normalizations we can investigate universal characteristics of the turbulent structures. Further, we performed LESs of turbulent channel flow and confirmed the viability of the proposed method. We obtained velocity profiles and the wall friction coefficient that correlate well with DNS results. Consequently, we are now able to predict the wall turbulence modulation for surfactant solutions with the LES method by estimating the spatial scale of the turbulent flow filtered with a viscosity-dependent correction function.
