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In this work, the flow of power-law fluids past a solid sphere with and without radial mass flux has been investigated numerically using a finite difference method based SMAC-implicit algorithm implemented on a spherical staggered grid arrangement. It is clearly shown that the flow and drag phenomena are strongly affected by the pertinent dimensionless parameters like Reynolds number (<I>Re</I>), power-law index (<I>n</I>) and the radial mass flux (<I>φ</I>). The effect of suction (<I>φ</I> < 0) on the flow profile is seen to be strong at high Reynolds numbers in the case of shear-thinning fluids (<I>n</I> < 1), whereas the reverse is seen in Newtonian and shear-thickening fluids (<I>n</I> ≥ 1). On the other hand, irrespective of the value of power-law index, the effect of injection (<I>φ</I> > 0) on the flow profile is significant at all Reynolds numbers. Regardless of the value of the power-law index, the pressure drag coefficient decreases as the value of <I>φ</I> decreases. On the other hand, the friction and total drag coefficients decrease as the value of <I>φ</I> decreases for Newtonian and shear-thinning fluids, whereas an opposite trend is seen in shear-thickening fluids. However, the total drag coefficient is reduced for suction (<I>φ</I> < 0) and augmented for injection (<I>φ</I> > 0) compared to that in the absence of radial mass flux. This is so for all values of power-law index. The present numerical results have been correlated empirically, thereby enabling the prediction of the drag coefficient (hence terminal velocity) in a new application.
- JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 42(8), 545-554, 2009-12-01
The Society of Chemical Engineers, Japan