LES of heat transfer in pipe flow of power-law fluids

Heat transfer of turbulent forced convection of power-law fluids, flowing in a heated horizontal pipe at isoflux conditions, is numerically analyzed by Large Eddy Simulations (LES), with the extended Smagorinsky model, for various power law indices (0.75≤n≤1.2) at different Reynolds and Prandtl numbers (4000≤Re s ≤12000 and 1≤Pr s ≤100) for a non-thermally-dependent fluid, at Pearson number Pn=0. A thermally-dependent fluid is also considered for the case n=0.75, at Re s =4000 and Pr s =1, for different Pearson numbers (0.5≤Pn≤5). To validate the present computations, the LES predictions are compared to the results reported in the open literature for the Nusselt number correlations at Pn=0. The LES predictions also allow a better understanding of the physical mechanisms involved in non-newtonian thermally-dependent fluid flows: with increasing Pn, the relative viscosity is enhanced towards the pipe center while the friction factor and the Nusselt number are significantly reduced.