# Rheology Cases

Generalized-Newtonian (non-Newtonian) rheology validation. Many process fluids -
shear-thinning broths and polymer solutions, yield-stress pastes and slurries - have
a viscosity that depends on the local deformation rate rather than being constant.
Nassu models this class through the generalized-Newtonian framework
(`models.rheology`): the apparent viscosity $\eta(\dot\gamma)$ is evaluated from the
local strain-rate magnitude $|S|$ and folded into the relaxation frequency, reusing
the same machinery the Smagorinsky LES model already uses (see the
[rheology theory chapter](../../docs/source/theory/rheology/index.md)).

These cases validate that framework against the exact fully-developed channel
profiles: the shear-thinning power-law flow, and the yield-stress
Bingham / Herschel-Bulkley flows with their unyielded central plug. Each is exercised
in 2D and 3D, across a 2:1 refinement interface, and (for the power-law) composed with
the LES model, plus a bit-for-bit neutral-limit regression against the constant-viscosity
solver.

```{toctree}
---
maxdepth: 1
---
01_power_law_channel/README.md
02_yield_stress_channel/README.md
```