Drag and Lift Force Acting on a Rotational Spherical Particle in a Logarithmic Boundary Flow

The drag and lift forces acting on a rotational spherical particle in a logarithmic boundary flow are numerically studied. The effects of the drag velocity and rotational speed of the sphere on the drag force are examined for the particle Reynolds number from 50 to 300 and for the dimensionless rotational angular speed of 0≤Ω≤1.0. The influence of dimensionless roughness height z_ 0 of the wall is also evaluated for z_ 0 ≤10. The results show that the drag forces on a sphere both in a logarithmic flow and in a uniform unsheared flow increase with the increase of the drag velocity. For 50≤Re_ p ≤300, the drag coefficient C-_ D increases with decreased roughness height z_ 0 . The time-averaged drag coefficient is also significantly affected by rotational speed of the sphere and roughness height z_ 0 . The lift coefficient C-_ L increases with increased rotational speed and decreases with increased roughness height.