# Generalized Newtonian rheology merged in next

**URL:** <https://gpusph.discourse.group/t/generalized-newtonian-rheology-merged-in-next/21>\
**Category:** Development\
**Created:** [March 14, 2019, 7:25pm UTC](https://gpusph.discourse.group/t/generalized-newtonian-rheology-merged-in-next/21 "2019-03-14T19:25:01Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![giuseppe.bilotta](https://yyz2.discourse-cdn.com/free1/user_avatar/gpusph.discourse.group/giuseppe.bilotta/32/72_2.png) [@giuseppe.bilotta](https://gpusph.discourse.group/u/giuseppe.bilotta)\
**Post date:** [March 14, 2019, 7:25pm UTC](https://gpusph.discourse.group/t/generalized-newtonian-rheology-merged-in-next/21/1 "2019-03-14T19:25:01Z")

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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.