Non-isothermal laminar channel flow

This article deals with the non-isothermal, laminar flow of a power-law fluid between parallel plates with a constant plate temperature. The fluids are assumed to be incompressible and to have constant physical properties except for the consistency-index, which latter quantity is assumed to vary exponentially with temperature. Calculations are performed on the “non-isoviscous” hydrodynamics and heat transfer rate. The results are presented as logarithmic mean Nusselt-numbers and dimensionless velocity distributions and pressure drops as a function of the dimensionless axial length in the channel and as a function of a quantity Q which measures the deviation of “isoviscous” fluid behaviour.The heat transfer rate appears to be a unique function of the velocity gradient at the wall, independent of the fluid rheology.All results have been summarized in a few practical approximations and are verified experimentally with pressure drop and heat transfer measurements of laminar, newtonian channel flow. It turns out that the results may be applied to flow between rectangular ducts up to aspect ratios H/B = 0·25.