Method of reflections for Stokes flow

The method of reflections successively scatters the disturbance from each rigid body off every other body to enforce their boundary conditions. For well-separated particles, each reflection is smaller by a power of particle size over separation.

A torque-driven sphere advects and rotates a distant force-free sphere through its rotlet. The incident rate of strain makes the second sphere emit a stresslet; the vorticity of that reflected field supplies the first correction to the original sphere's angular velocity.