Description: Two contact enhancements associated with pore fluid diffusion are provided.

First, fluid permeability can be specified for contact interfaces. Previously, pore fluid pressure was always enforced to be equal on both sides of a contact interface, corresponding to no resistance to flow (or infinite permeability) across the interface. Now, a finite or zero value of this permeability can be specified instead.

Pore fluid flow across and into a contact interface now occurs only where contact surfaces are separated by less than a threshold distance. By default, flow only occurs where the surfaces are separated by less than a characteristic surface facet dimension. Previously this flow occurred regardless of the separation distance, although the pore flow models at a contact interface are intended for situations with nearby surfaces (more sophisticated pore fluid flow models are available if an interface is modeled with cohesive elements, as discussed in “Defining the constitutive response of fluid within the cohesive element gap,” Section 31.5.7 of the Abaqus Analysis User's Manual).

An additional enhancement is that contact can be modeled for coupled flow-heat transfer analyses. Previously, contact could be modeled for coupled pore pressure-displacement analyses, but not with the additional thermal coupling.