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).

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.