Discussion Forum

Dear all,

I am running a coupled HM model for porous media. In this model, the water retention curve is given Van Genuchten model, which is a highly nonlinear function, shown as:. In this equation, Se is the effective degree of saturation, alpha is related to the gas entry value, Hc is the capillary height, N,M are the parameters determined from experiment. I coupled, alpha, with the volumetric strain of the porous media. However, I found the convergence issues always occur when the volumetric strain experience a fast change. As this coupling is very important to the whole model, I cannot neglect it.I think this issue should be caused by highly nonlinear property of the Van Genuchten. But I still cannot find a good way to solve it. Does anyone have experiences to treat such a convergence issue? Thank you so much for your help.

Yu