The pressed oil-extraction process is essentially a process of oil seepage through porous cake-shaped media. Permeability of seepage field changes along with the change of porous media caused by press pressure. The change of permeability affects fluid pressure and effective pressure of oil cake pores, which means that porosity is influenced. On the contrary, the change of porosity also has an impact on permeability. The interaction between the seepage and rheology fields is termed as fluid-solid coupling. If rheology of oil cakes is considered, the fluid-solid coupling seepage with the rheological properties is the essence of the pressed oil-extraction process. In the present study, we studied a permeability model based on the deformable and rheological properties of oilseed cakes and the effective stress. The seepage and rheology fields were analyzed by alternative application of the finite difference and finite element methods. The finite element calculation model of nonlinear rheology field was established by the time step-initial strain method. We used flax and cotton seeds as examples to perform numerical simulation and calculate the displacement and pore fluid pressure dissipation of flaxseed and cottonseed oil during the press process.
