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-   -   Is this the correct setup? Non-Newtonian fluent Problem (https://www.cfd-online.com/Forums/fluent/171175-correct-setup-non-newtonian-fluent-problem.html)

 DanielH May 4, 2016 01:57

Is this the correct setup? Non-Newtonian fluent Problem

Problem: You have a thickened (non-Newtonian) fluid passing through a water bottle top, where you know the initial pressure is vacuum (0kpa) and the a lab results gives you a flow rate of say 0.000779kg/s and the static pressure drop was seen as 10kPa with laminar flow. (assuming model and mesh is done and fluent set up is only needed)

Models: Only viscous (Laminar)
Material: fluid is almost like water, copy water poperties and change viscosity to non-Newtonian power law and add parameters

Cell Zone conditions: Change it to you non-Newtonian fluid
Boundary conditions:Set operation conditions to 0pa
Define inlet as Mass-flow-inlet at 0.000779kg/s
Define Outlet and Outflow
Define interior and walls
Solution methods: Use Simple
Solution controls: Change nothing
Solution Initialization: Hybrid with 10 steps, initialize
Run Calculation: run with 250 iterations and what for convergence

Wala take results???? Is this correct or have I missed something

 DanielH May 9, 2016 00:59

 DanielH May 18, 2016 01:05

Also like to add I am getting a shear rate of crazy amount from a range of 20-10,000 1/s

 bhargavbharathan May 31, 2016 11:07

Hi,

Your set up looks fine. I suggest going to monitors and setting the residuals to atleast 1e-5 for better precision.

As for the shear rate, where did you arrive at numbers as big as 20-10,000 1/s? I generally give small numbers of the order 0.01.

-BB

 DanielH June 16, 2016 20:16

I meant strain rate... Sorry somehow I was must have misread it... but for my Wall Shear stress it is around 0 (possible very very small) to 43pa.. Btw thank you for the reply, what I am trying to find is Strain and Shear rate range to determine if the simulation is viable though I am not sure if I am using the right methods to do so.. I am just using Contours and using the range they give me. :)