Non-newtonian fluid in Nanofluidx

Nicolas Borquez

Hi Altair Community

How can I incorporate yield stress for non-Newtonian fluids in Nanofluidx version 2022.2?

Regards

acupro

Yield stress as in complete solid to fluid transition is not supported, but going from very high viscosity fluid to low viscosity fluid is possible by choosing right model coefficients for the target "yield" stress point, though it may be somewhat costly in terms of timestep size. Modeling yield in this way is not specific to nFX.

 

For a shear-thinning Cross fluid, k would move the yield point while n modifies the rate of change across yield point. reordering the equation like below, assuming yield at average viscosity and knowing the target yield point, should help with choosing k and n.

See the attachments for some examples.

Figure_1.png

Figure_2.png

Figure_3.png