Good morning, I was wondering if you could help me solve a problem with a poroelastic model with COMSOL Multiphysics. It is a very simple model preliminary to my real study to understand the role of Poisson's ratio on the simulation, keeping all other parameters constant. The model is a two-dimensional poroelastic model constituted by a circle with a circular cavity inside subjected to a radial pressure . Being the model poroelastic, I expect that the internal pressure generates a movement of fluid and in particular I expect the material area not increase but actually with coefficients poisson low there is an increase in surface. I can not understand the physical sense of this increase in surface area. What generates the increase in surface area?