Non-Newtonian shear-thinning flows past a flat plate

Abstract

The present work attempts to characterize the flow of shear-thinning power-law fluids past a flat plate as the angle of attack is varied. The effects of Reynolds number, shear-thinning characteristics and angles of attack on drag and lift of the flat plate were investigated, both experimentally and numerically. Carbopol 940 solutions of various strengths were used to approximate purely viscous shear-thinning non-Newtonian fluids for the experiments. An important finding is that at small angles of attack when the wall shear forms the dominant contribution to the drag, the non-Newtonian shear-thinning property leads to drag reduction, whereas for large angles of attack, when pressure-induced form drag is dominant, shear-thinning results in drag augmentation. This is consistent with the trend shown in the present study that lift increases as shear-thinning increases. It is demonstrated that a simple linear model developed for Newtonian creeping flow can be used to estimate the effect of angle on drag given both the drag coefficients corresponding to normal and tangential flow to the plate.

Laminar forced convection heat transfer from a two-dimensional transverse plate in Bingham plastic fluids

“…However, for the normal configuration, the flow is unlikely to be steady as has been assumed in this study. Also, while his values of the critical Reynolds number in shear-thinning fluids are consistent with that of Wu and Thomson [26], the corresponding values in shear-thickening (n > 1) fluids are very high indeed, e.g., Re $ 10 6 for n = 2. In other words, the boundary layer flow approximation provides a very poor representation for shear-thickening fluids.…”

“…In contrast, despite the frequent occurrence of shear-thinning and yield stress fluids in scores of industrial settings, little numerical and experimental studies on the momentum and heat transfer characteristics for this configuration in such fluids have been reported in the literature. For instance, in an extensive study, Wu and Thompson [26] studied the effect of angle of incidence of power-law (n < 1) fluids on a two-dimensional plane surface. Their experimental results of drag coefficients for both tangential and transverse flow were consistent with their finite element method based predictions up to about Re $ 10.…”

Laminar flow and heat transfer in the boundary-layer of non-Newtonian fluids over a stretching flat sheet

“…A similarity solution to the boundary-layer flow of a power-law non-Newtonian fluid over a horizontal flat plate was obtained in [11]. Wu and Thompson [12] experimentally found that even if the Reynolds number is not large, the boundary-layer equations are still valid and accurate for the flow of shear-thinning fluids. Denier and Dabrowski [13] investigated the boundary-layer equations describing the steady uniform flow of a non-Newtonian fluid past a flat plate.…”

Effects of Heat Source/Sink and Chemical Reaction on MHD Maxwell Nanofluid Flow Over a Convectively Heated Exponentially Stretching Sheet Using Homotopy Analysis Method

“…Single constitutive equation exhibiting all the properties of non-Newtonian fluids is not available due to the diversity of these fluids in their constitutive behavior, simultaneous viscous and elastic properties. Thus, several models of non-Newtonian fluids have been proposed to fit well with the experimental observations [5]. The non-Newtonian fluids can be classified into the following three types, i.e., (i) differential type (ii) rate type and (iii) integral type.…”