Questions about "Dispersed Fluid Model"

safikhani_hamed · October 21, 2013, 03:03

Dear Friends,
I want to model a two phase flow in CFX, in fact my problem can be performed by dispersed fluid model in CFX but I have three questions about this model :
1-Is this model Eulerian or Lagrangian? (I think it is Eulerian but I am not sure)

2- Is there any limitation about volume fraction of 2nd phase during the use of this model ? in my problem the volume fraction of 2nd phase is 1%.

3- Can we using this model for compressible fluids ?

With Best Regards

ghorrocks · October 21, 2013, 05:22

1. Eularian. If you are using a continuum approach it is Eularian. If you are modelling discrete particles it is lagrangian.
2. It depends on exactly the Eularian model you are using. Different models have different volume fraction limitations.
3. Again, depends on the Eularian model. But I think most (if not all) of them are OK with compressible flow.

safikhani_hamed · October 21, 2013, 07:58

Thank you ghorrocks but in fact I do not know what do you mean by this sentence "It depends on exactly the Eularian model you are using" ?
I want to model a fluid-fluid flow using dispersed fluid model by CFX ? (one fluid continuous fluid with 99% volume fraction and the other dispersed fluid with 1% volume fraction).

Best Regards

ghorrocks · October 21, 2013, 08:13

There are lots of different ways of modelling multi-phase models in a Eularian context - like homogenous/inhomogeneous, MUSIG, algebraic slip, free surface. They all are very different.

safikhani_hamed · October 21, 2013, 08:23

Dear ghorrocks
Yes you are right, how can I find the limitation for each model ?

Best

ghorrocks · October 21, 2013, 08:24

The CFX documentation is a good place to start.

safikhani_hamed · October 21, 2013, 08:32

sorry for consuming your time but I searched in CFD documentation and I did not find any thing about volume fraction limitations .

BEST

safikhani_hamed · October 21, 2013, 08:35

sorry for consuming your time but I searched in CFX documentation and I did not find any thing about volume fraction limitations .

BEST

safikhani_hamed · October 21, 2013, 09:18

Quote:

Originally Posted by ghorrocks

The CFX documentation is a good place to start.

Dear ghorrocks
In fact again I searched CFX documentations but I did not find anything about volume fraction limitations. Would you please help me ?

BEST

ghorrocks · October 21, 2013, 17:28

I am not going to re-write the documentation on the forum, I have better things to do with my time.

Look in the theory manual of the CFX documentation, and get some of the references it cites.

safikhani_hamed · October 23, 2013, 12:19

Quote:

Originally Posted by ghorrocks

I am not going to re-write the documentation on the forum, I have better things to do with my time.

Look in the theory manual of the CFX documentation, and get some of the references it cites.

Dear ghorrocks
I have really wondered from your type of talking, that was so discourtesy, please know that you do not perform a very important work and you only answer the questions of some new software users from morning till night

.

BEST

October 21, 2013, 03:03	Questions about "Dispersed Fluid Model"	#1
safikhani_hamed Member Hamed Join Date: Oct 2009 Posts: 64 Rep Power: 16	Dear Friends, I want to model a two phase flow in CFX, in fact my problem can be performed by dispersed fluid model in CFX but I have three questions about this model : 1-Is this model Eulerian or Lagrangian? (I think it is Eulerian but I am not sure) 2- Is there any limitation about volume fraction of 2nd phase during the use of this model ? in my problem the volume fraction of 2nd phase is 1%. 3- Can we using this model for compressible fluids ? With Best Regards

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October 21, 2013, 05:22		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	1. Eularian. If you are using a continuum approach it is Eularian. If you are modelling discrete particles it is lagrangian. 2. It depends on exactly the Eularian model you are using. Different models have different volume fraction limitations. 3. Again, depends on the Eularian model. But I think most (if not all) of them are OK with compressible flow.

October 21, 2013, 07:58		#3
safikhani_hamed Member Hamed Join Date: Oct 2009 Posts: 64 Rep Power: 16	Thank you ghorrocks but in fact I do not know what do you mean by this sentence "It depends on exactly the Eularian model you are using" ? I want to model a fluid-fluid flow using dispersed fluid model by CFX ? (one fluid continuous fluid with 99% volume fraction and the other dispersed fluid with 1% volume fraction). Best Regards

October 21, 2013, 08:13		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	There are lots of different ways of modelling multi-phase models in a Eularian context - like homogenous/inhomogeneous, MUSIG, algebraic slip, free surface. They all are very different.

October 21, 2013, 08:23		#5
safikhani_hamed Member Hamed Join Date: Oct 2009 Posts: 64 Rep Power: 16	Dear ghorrocks Yes you are right, how can I find the limitation for each model ? Best

October 21, 2013, 08:24		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The CFX documentation is a good place to start.

October 21, 2013, 08:32		#7
safikhani_hamed Member Hamed Join Date: Oct 2009 Posts: 64 Rep Power: 16	sorry for consuming your time but I searched in CFD documentation and I did not find any thing about volume fraction limitations . BEST

October 21, 2013, 08:35		#8
safikhani_hamed Member Hamed Join Date: Oct 2009 Posts: 64 Rep Power: 16	sorry for consuming your time but I searched in CFX documentation and I did not find any thing about volume fraction limitations . BEST

October 21, 2013, 17:28		#10
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I am not going to re-write the documentation on the forum, I have better things to do with my time. Look in the theory manual of the CFX documentation, and get some of the references it cites.