How to redefine the washburn equation

[Xknightfyy]

Dear Professor Jeff,

First, with your help, I made some achievements, but now my model still faces some problems that need to be modified. Among them, the capillary pressure threshold of my invasion process needs to be corrected using the following formula, which looks more like The combination of invasion percolation and drainage, I don’t know how to redefine the washburn equation. I tried using phase[pore.pressure].max-phase[pore.pressure].min to define it, but the positive and negative signs in the formula I need to know the order of invasion, how should I define it? I apologize if I have disturbed you and I look forward to hearing from you.

Best wishes