THE EFFECT OF SHEAR THINNING BEHAVIOUR ON TURBULENT PIPE FLOW

Direct numerical simulation of the weakly turbulent flow of non-Newtonian fluids is undertaken for two different generalised Newtonian rheology models using a spectral element--Fourier method. Results for a power law (shearthinning) rheology agree well with experimentally determined logarithmic layer correlations and with other previously published experimental work. As the flow index becomes smaller for the same Reynolds number, the flow deviates further from the Newtonian profile and the results suggest that transition is delayed. Predicted friction factors fall above those in the literature, but below the Newtonian values indicating that shear thinning behaviour alone can result in drag reduction. Results for a Herschel-Bulkley model (yield stress + shear-thinning) are compared to corresponding experimental measurements and found to be in good agreement. Use of this DNS technique shows great promise in understanding transition and turbulence in non-Newtonian fluids. NOMENCLATURE

[1]  Renzo Piva,et al.  DNS of wall turbulence: dilute polymers and self-sustaining mechanisms , 2002 .

[2]  L. Pullum,et al.  Weakly Turbulent Pipe Flow of a Power Law Fluid , 2022 .

[3]  den Jmj Jaap Toonder,et al.  Reynolds number effects in a turbulent pipe flow for low to moderate Re , 1997 .

[4]  A. B. Metzner,et al.  Turbulent flow of non‐newtonian systems , 1959 .

[5]  P. Moin,et al.  Large-eddy simulation of turbulent confined coannular jets , 1996, Journal of Fluid Mechanics.

[6]  Murray Rudman,et al.  Non-Newtonian Turbulent and Transitional Pipe Flow , 2002 .

[7]  R. G. Deissler.  ANALYTICAL INVESTIGATION OF TURBULENT FLOW IN SMOOTH TUBES WITH HEAT TRANSFER WITH VARIABLE FLUID PROPERTIES FOR PRANDTL NUMBER OF 1 , 1950 .

[8]  M. Escudier,et al.  Pipe flow of a thixotropic liquid , 1996 .

[9]  M. Escudier,et al.  Drag reduction in the turbulent pipe flow of polymers , 1999 .

[10]  Fernando T. Pinho,et al.  Flow of non-newtonian fluids in a pipe , 1990 .

[11]  Antony N. Beris,et al.  Pseudospectral simulation of turbulent viscoelastic channel flow , 1999 .

[12]  S. Schmidt,et al.  Spectral Element Based Simulation of Turbulent Pipe Flow , .

[13]  M. Malin,et al.  Turbulent pipe flow of power-law fluids , 1997 .

[14]  G. Karniadakis.  Spectral element—Fourier methods for incompressible turbulent flows , 1990 .

[15]  Murray Rudman,et al.  LARGE EDDY SIMULATION OF TURBULENT PIPE FLOW , 1999 .

[16]  Robert A. Handler,et al.  Direct numerical simulation of the turbulent channel flow of a polymer solution , 1997 .