
Is it possible to simulate the filling process (or any such one, involving contact) for a thixotropic fluid, i.e. for which the viscosity depends on a species obeying a transport equation? Actually, yes. A typical simple modelling case could involve a viscosity that depends on the residence time distribution or on the strain accumulation. In both cases, a species has to be defined, which obeys a transport equation with an appropriate source term. The typical equation for the residence time distribution is DT/dt = 1, while the typical equation for the strain accumulation would be DG/Dt = gdot. Beyond that, the viscosity can depend on T or G... Care shuold be taken for velocity boundary layers. However, the situation can be less sensitive when simulating transient flows.

