Numerical modelling of electro-osmotically driven flow within the microthin liquid layer near an earthworm surface - a biomimetic approach

Abstract

The electro-osmotic flow near an earthworm body surface is a basic electrokinetic phenomenon that takes place when the earthworm moves in moist soil. The flow within a microthin liquid layer near earthworm's body surface is induced by the electric double layer (EDL) interaction. Such a microscale electro-osmotic flow plays a role of lubrication between the earthworm's body surface and the surrounding medium of moist soil and reduces surface adhesion. In the current paper, the electro-osmotic flow near earthworm surface is numerically simulated to further understand the mechanism of antisoil adhesion. A lattice Poisson method is first employed to solve electric potential and charge distributions in the EDL along an earthworm surface; the external electric field is then obtained by solving the Laplace equation. The motion of electro-osmotic flow controlled by Navier-Stokes equations is simulated by the lattice Boltzmann method. Typically, the simulation of electro-osmotic flow shows that moving vortices, which likely contribute to antisoil adhesion, can be formed near the earthworm body surface by the non-uniform and variational electrical force.