Learning Forum

[Marcos Silvestre]

I'm trying to compare the analytical solution of a bingham fluid, laminar in steady state in 2 cases:

Case 1: External wall rotating 0.5 rad/s and internal wall stationary

Case 2: Internal wall rotating 0.5 rad/s and external wall stationary

For case 2 the results are very satisfatory, with a max deviation of 2,04%, Deviation % = (V analytc - V simulate)/V analytc *100

But using the same parameters for the Case 1 the deviation is around 60%, I've already tried to change the solve method or initial valus but doesnt changed a lot. I will post here the parameters I'm using.

Here are the parameters I'm using for now in both cases:

or

[Rob]

Please can you post an image showing the mesh? 

[Marcos Silvestre]

 

The max cells I can use is 900k because i’m using the student version, I did the mesh using Gambit.

 

[Rob]

The velocity field looks sensible, what shear (viscosity) are you predicting in Fluent?  If you look at a 2d model you can use significantly more mesh. 

I strongly advise switching to either Ansys Meshing (2d, found in Workbench) or Fluent Meshing (3d, use the standalone mode) rather than GAMBIT. Whilst I still like GAMBIT it's not been developed in over 15 years and it's not used in industry (much) any longer. 

[Marcos Silvestre]

The fluid would have the properties of water but with an initial shear stress, so it would be the valor of k=0,001003 (consistente index)

[Rob]

If you compare the viscosity fields how do they differ?