As of today, the next branch also includes the possibility to use some generalized Newtonian rheological models. Currently, the supported models are the Bingham, power-law and Herschel–Bulkey models. For Bingham and Herschel–Bulkley, the regularized versions (Papanastasiou, Alexandrou) are available as well. We also support the single-exponent DeKee & Turkotte model, optionally with a regularized yield strength (Zhu model). Adding other models where the apparent viscosity can be computed from the shear rate is rather straightforward.
Multi-fluid is supported, but it is not (currently) possible to have different rheological models for different fluids. However, since Herschel–Bulkley is a wide-encompassing rheology that can also be used to obtain Newtonian, Bingham and power-law behavior by setting the rheological parameters appropriately, the only combination that cannot be satisfied is when one fluid should be modelled by the DeKee & Turkotte model while the other would need to be modelled with Herschel–Bulkley. If the need arises, a rheological model that combines both the power-law and exponential behavior can be added to the list of supported models.