[Stejohn]

Greetings!
I´m trying to simulate laminar flow of Bingham fluid in Fluent 12.1 by using Herschel - Bulkley model. I´ve got constants which are needed to define Bingham fluids parameters...binghams apparent viscosity and value of yield shear stress from experiment.

But there is problem with "critical shear rate" column...I have no idea what should i type into this. Is there anyone whou could advice me?

Thanks for every proposal!

[Stejohn]

No proposals from local experts?

[brucecumt]

Originally Posted by Stejohn

Greetings!
I´m trying to simulate laminar flow of Bingham fluid in Fluent 12.1 by using Herschel - Bulkley model. I´ve got constants which are needed to define Bingham fluids parameters...binghams apparent viscosity and value of yield shear stress from experiment.

But there is problem with "critical shear rate" column...I have no idea what should i type into this. Is there anyone whou could advice me?

Thanks for every proposal!

I get stuck on this problem as well. Does anyone have any idea about this problem. How to determine the "critical shear rate" in Bingham or Herschel-Bulkley model in ANSYSFLUENT? Anyhelp will be appreciated!

[Stejohn]

Originally Posted by brucecumt

I get stuck on this problem as well. Does anyone have any idea about this problem. How to determine the "critical shear rate" in Bingham or Herschel-Bulkley model in ANSYSFLUENT? Anyhelp will be appreciated!

I´ve figured it out. Bingham fluid behaves like "solid" mass in area under critical shear rate. You should insert number near to zero to this column. I usualy insert 0,01 or 0,001 and it works pretty well.

[brucecumt]

Originally Posted by Stejohn

I´ve figured it out. Bingham fluid behaves like "solid" mass in area under critical shear rate. You should insert number near to zero to this column. I usualy insert 0,01 or 0,001 and it works pretty well.

Thank you mate. I found if the critical shear rate you input is too small, some numerical instability will occur, especially when the flow speed is very low. Anyway, I think this parameter is almost impossible to get from the lab test. The only way is to try different number and see if the simulation results have a good agreement with pratice. Keep changing it until it yields reasonable result.