A note on the screening of hydrodynamic interactions, in electrophoresis, and in porous media

Abstract:

We consider two situations where hydrodynamic interactions are said to be “screened”: hydrodynamics in a gel or in a porous medium, and electrophoresis in an electrolyte. We focus on the corresponding Green functions, and show that the flow fields are similar in the two cases. Contrarily to statements often made, the fluid velocity decays algebraically with distance (), i.e. not exponentially. We point out that the pressure fields are different in the two cases.