Interfacial dynamics simulation between soil and earthworm surface

A simulation model of the interfacial dynamics between soil and earthworm surface was developed by PFC2Dsoftware.The contact interface,the contact force field,the contact particle number and contact sliding resistance of smooth surface and corrugated surface was analyzed and compared.The results show that,when the resultant force of the friction and the particle backward thrust on the corrugated surface is less than the friction on the smooth surface,the corrugated surface can reduce the resistance.If the particle backward thrust on the corrugated surface is too large,the corrugated surface increases the resistance.When moving forward,the corrugated surface disturbs the soil more than the smooth surface.As the vertical load increases,the sliding resistances of both smooth and corrugated surfaces increase,but the drag-reduction effect of the corrugated surface declines.The sliding resistance increases with the forward speed,but the increase trend of the corrugated surface is smaller than that of the smooth surface,and the drag-reducing effect of the corrugated surface is more obvious at high-speed.The results also show that the drag-reducing capability of the earthworm skin is related to the interfacial contact characteristics and externalconditions.This study provides the reference for revealing the drag-reduction mechanism of non-smooth surface.