Thermal processing of viscous non-Newtonian fluids in annular ducts: effects of power-law rheology, duct eccentricity, and thermal boundary conditions

Forced convection heat transfer in fully developed laminar flows of power-law fluids in eccentric annular ducts is computationally analyzed. With an insulated outer surface, the heating or cooling on the inner surface is modeled by two fundamental boundary conditions – uniform axial heat flux (H1) and constant wall temperature (T) – commonly encountered in thermal processing applications. Numerical solutions for the velocity and temperature distributions, isothermal frictions factors, and Nusselt numbers for annular ducts of varying aspect ratios (0.2⩽r∗⩽0.8) and inner core eccentricity (0⩽ε∗⩽0.6) are presented for both shear-thinning (0.2⩽n<1) and shear-thickening (1