Fluctuating force-coupling method for interacting colloids

Brownian motion plays an important role in the dynamics of colloidal suspensions. It affects rheological properties, influences the self-assembly of structures, and regulates particle transport. While including Brownian motion in simulations is necessary to reproduce and study these effects, it is computationally intensive due to the configuration dependent statistics of the particles’ random motion. We will present recent work that speeds up this calculation for the force-coupling method (FCM), a regularized multipole approach to simulating suspensions at large-scale. We show that by forcing the surrounding fluid with a configurationindependent, white-noise stress, fluctuating FCM yields the correct particle random motion, even when higherorder terms, such as the stresslets, are included in the multipole expansion. We present results from several simulations demonstrating the effectiveness of this approach for modern problems in colloidal science and discuss open questions such as the extension of fluctuating FCM to dense suspensions.