LES of heat transfer in pipe flow of power-law fluidsReport as inadecuate

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1 MSME - Laboratoire de Modélisation et Simulation Multi Echelle 2 Dipartimento di Ingegneria Meccanica e Aerospaziale, Università La Sapienza, 00184 Rome, Italy

Abstract : 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.

Keywords : LES non-newtonian power-law fluids turbulent pipe flow heat transfer

Author: Paulin Gnambode - Meryem Ould-Rouiss - Xavier Nicolas - Paolo Orlandi -

Source: https://hal.archives-ouvertes.fr/


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