Calculating Stokes number of flow

amin.z · March 25, 2015, 14:32

Hi friends

Is there any way to calculating Stokes number for a 2 phase flow in a duct?
Does fluent calculates this number? Can we use fluent results for it?

Saidul · June 4, 2015, 02:26

Did you get anything regarding stokes number? I am also using FLUENT and if possible, I want to do something related stokes number.

Thanks anyway.
saeed

CeesH · June 4, 2015, 05:21

Hi,

Are you using DPM multiphase or Eulerian multiphase?

As far as I know FLUENT does not calculate the stokes number directly (but if you have a certain drag law it does calculate many of the parameters in there to determine drag).

It's easy to determine via UDF though.

If you have DPM, I'd use DPM-scalar-update to calculate the stokes number and write it to a DPM scalar, such that you can extract the number for every particle at any snapshot of time.

If you are using Eulerian multiphase with a single bubble/particle size, you can use define_execute_at_end to calculate it for each grid cell, and store in the UDM. Of course there is a problem if you use a population balance; then you need to base it on the mean diameter or so, but of course there will be a distribution in stokes number there.

amin.z · June 5, 2015, 04:20

I think fluent cannot report Stokes number directly,
but as Cess said, there are several advance ways to computing Stokes number,
and the simplest way is using simplified equation of Stokes number:

Stokes= [(dispersed phase density )*(career phase velocity)*(particle diameter)^2]/ [18*(dynamic viscosity of career phase)*(characteristic length)]

it's a simple way and has a some errors but it's good for start!

March 25, 2015, 14:32	Calculating Stokes number of flow	#1
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 15	Hi friends Is there any way to calculating Stokes number for a 2 phase flow in a duct? Does fluent calculates this number? Can we use fluent results for it?

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June 4, 2015, 02:26		#2
Saidul Member S. Morichika Join Date: Aug 2014 Posts: 62 Rep Power: 12	Did you get anything regarding stokes number? I am also using FLUENT and if possible, I want to do something related stokes number. Thanks anyway. saeed

June 4, 2015, 05:21		#3
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	Hi, Are you using DPM multiphase or Eulerian multiphase? As far as I know FLUENT does not calculate the stokes number directly (but if you have a certain drag law it does calculate many of the parameters in there to determine drag). It's easy to determine via UDF though. If you have DPM, I'd use DPM-scalar-update to calculate the stokes number and write it to a DPM scalar, such that you can extract the number for every particle at any snapshot of time. If you are using Eulerian multiphase with a single bubble/particle size, you can use define_execute_at_end to calculate it for each grid cell, and store in the UDM. Of course there is a problem if you use a population balance; then you need to base it on the mean diameter or so, but of course there will be a distribution in stokes number there.

June 5, 2015, 04:20		#4
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 15	I think fluent cannot report Stokes number directly, but as Cess said, there are several advance ways to computing Stokes number, and the simplest way is using simplified equation of Stokes number: Stokes= [(dispersed phase density )(career phase velocity)(particle diameter)^2]/ [18(dynamic viscosity of career phase)(characteristic length)] it's a simple way and has a some errors but it's good for start!