Effective interactions between inclusions in complex fluids driven out of equilibrium

The concept of fluctuation-induced effective interactions is extended to systems driven out of equilibrium. We compute the forces experienced by macroscopic objects immersed in a soft material driven by external shaking sources. We show that, in contrast with equilibrium Casimir forces induced by thermal fluctuations, their sign, range, and amplitude depend on specifics of the shaking and can thus be tuned. We also comment on the dispersion of these shaking-induced forces, and discuss their potential application to phase ordering in soft materials.