Entrance pressure losses for power-law fluid at small Reynolds number

Abstract

Finite-element results are presented for the extra pressure loss for a power-law fluid due to an abrupt contraction of ratio 2, 4, 8 and ∞ for both the axisymmetric and planar cases. Contrary to earlier results in the literature, it is found that the variational result of Duda and Vrentas forms a very good upper bound for the axisymmetric case, even for small values of the power-law index. This variational method has now been extended to the planar case, where it is again found to form a very good upper bound.