On the Magnus effect of a rotating porous circular cylinder in uniform flow: A lattice Boltzmann study

In this paper, a multiple-relaxation-time-lattice Boltzmann method is used to simulate the steady fluid flow through and around a rotating porous circular cylinder in uniform flow. This study aims at investigating the effect of Darcy number ( 10 (-6) <= Da <= 10(-2)), velocity ratio (0 <= VR <= 2), and Reynolds number (Re = 20 and 40) on the Magnus lift as well as on the flow pattern and pressure coefficient inside and around the rotating porous cylinder. The results reveal that besides the enveloping and detached wakes reported in the literature for rotating solid cylinders, in this study, a new type of the wake called confined wake is observed within the rotating porous cylinders at high Darcy numbers and velocity ratios of less than one. It is seen that the Magnus lift increases almost linearly with the velocity ratio for Da <= 10(-3); however, through curve-fitting, the rate of increase is shown to decrease with Darcy number in a non-linear manner. For Darcy numbers higher than 10(-3), the Magnus lift varies non-linearly with both the velocity ratio and Darcy number in such a way that, interestingly, for R e = 40 and very high Darcy numbers of 7.5 x 10(-3) and 10(-2), the Magnus lift becomes negative showing a behavior called the inverse Magnus effect.