Forces and moments on a rigid rolling sphere in wall-bounded linear shear flows

Understanding drag and lift forces as well as moments exerted on a finite-sized particle in the wall vicinity is a problem of key interest in various engineering applications including aerosol transport, and lift-off of sand particles on sea/ocean shores.Simulations based on high-order parallel spectral element method (Nek5000) are being pursued to investigate the flow past a finite-sized particle. The particle is located in the vicinity of a solid wall and embedded in a linear shear flow. A range of particle location away from the wall has been considered, ranging from almost touching the wall to farther away. We consider a range of Reynolds (Re) numbers varying from $10$ to $200$, where Re is defined based particle diameter and local velocity at particle center. The lift and drag forces as well as the moments are calculated and show a substantial increase in the lift coefficient ($C_L$) as the particle moves closer to the wall and in the limit the particle sits on the wall. The contributions of the viscous and pressure terms to the lift coefficient, $C_L$, will be presented along with comparison to experimental measurements. We then consider the case of rolling particle on a wall for varying speeds to understand the lift and moments mechanisms generated. Results obtained from these simulations will be compared with experiments as well as low Re theory.