Lid-driven cavity flow-induced dynamics of a neutrally buoyant solid: Effect of Reynolds number, flexibility, and size

The present work is on Fluid flexible-Solid Interaction (FfSI), involving a recirculating flow-induced motion of a neutrally buoyant and deformable circular solid. For a Newtonian fluid flow and neo-Hookean flexible-solid deformation, a single FfSI solver-based on fully Eulerian and monolithic approaches-is used. The effect of Reynolds Number Re (20-500), volume fraction phi (1%-12%) of the solid, and its non-dimensional shear modulus G* (0.02 - 1) on transient/periodic flow-induced solid-motion and the associated FfSI analysis is presented. The solid undergoes a transient spiraling motion before attaining a periodic orbit-based limit cycle. The flow also attains the periodic state after the initial transients. Time-averaged flow velocity-magnitude & lang;v*& rang; surrounding the limit cycle increases with increasing Re, increasing G*, and decreasing phi. Equivalent radius r(eq)* of the limit cycle and time-averaged velocity-magnitude & lang;v(c)*& rang; of the centroid of the solid increase with increasing Re and decrease with decreasing G* (or increasing flexibility) and increasing volume fraction phi (or size) of the solid. Also, frequency f* of the limit cycle decreases with increasing Re and remains almost constant with G* and phi. With increasing phi, the limit cycle undergoes a transition from the single loop to double loop beyond a critical volume fraction phi(c) = 2%. A critical Reynolds number Re-c, below which the periodic limit cycle collapses to a point, decreases with decreasing phi. Our findings will help in the prediction and control of the motion of the solid in a bounded fluid flow involving solids of varying flexibility, which is relevant to a wide range of industrial and biological applications.

Automated summary

This study investigates the motion induced by a recirculating flow in a neutrally buoyant and deformable circular solid. Results show that the solid undergoes transient spiraling motion before reaching a periodic orbit-based limit cycle. The flow also transitions into a periodic state after initial transients. The time-averaged flow velocity and centroid velocity of the solid increase with increasing Reynolds Number, non-dimensional shear modulus, and decreasing solid volume fraction. The equivalent radius of the limit cycle and its frequency increase with Reynolds Number and decrease with decreasing shear modulus or increasing solid volume fraction. The transition from a single loop to a double loop limit cycle occurs when the solid volume fraction exceeds a critical value. These findings are important for predicting and controlling the motion of solids in fluid flows, which has applications in various industries and biology.