Soft-lubrication interactions between a rigid sphere and an elastic wall
Résumé
The motion of an object within a viscous fluid and in the vicinity of a soft surface induces a hydrodynamic stress field that deforms the latter, thus modifying the boundary conditions of the flow. This results in elastohydrodynamic (EHD) interactions experienced by the particle. Here, we derive a soft-lubrication model, in order to compute all the forces and torque applied on a rigid sphere that is free to translate and rotate near an elastic wall. We focus on the limit of small deformations of the surface with respect to the fluid-gap thickness, and perform a perturbation analysis at leading order in dimensionless compliance. The response is computed in the limiting cases of thick and thin elastic materials. The normal force is also obtained analytically using the Lorentz reciprocal theorem and agrees with the numerical results.