Need advice on softwares working for dilute gas flow

Mason · July 1, 2010, 17:54

Hello everyone,

I'm currently working on a project that involves dilute/rarefied gas flow in a pipe. The inlet pressure is about 1-10 Pa, and the Kundsen number of the flow is around 0.1-0.2, as my estimation. Clearly, the flow is in the slip flow regime or transitional flow regime. To my knowledge, CFD using N-S equations might still work in this regime, with some tweaks. My question is, what is the best commercial CFD software out there that will work for my project? I've tried Comsol Multiphysics, using both incompressible N-S mode/weakly compressible N-S with no-slip/slip boundary conditions, but the modeling results do not match the experiements. I wonder if there is any other CFD software that will work better for dilute gas flow. Or, do I have to use DSMC? The problem with DSMC is that the scale of my model is pretty big, and a 3-D DSMC modeling might be too big to handle. Thank you for your suggestion/advice.

Andre van der Walt · July 16, 2010, 05:55

Hi Mason, how big is the regime that you would like to model?

Mason · July 18, 2010, 22:08

Hi Andre,

Thanks for replying. The object I'm trying to model is about 40 inches long, and 3 inches in diameter. It's pretty big. Do you know any software that deals with dilute gas in such a big domain? Also, is there any DSMC software that is parallelized and can run on a cluster machine or a multi-processor machine?

Quote:

Originally Posted by Andre van der Walt

Hi Mason, how big is the regime that you would like to model?

Andre van der Walt · July 19, 2010, 10:40

Hi Mason

I think DSMC is probably the best method to go. Can the simulation be set up as an axi-symmetric problem? If so you can use the DS2V code of Bird fairly easy, without worrying about not knowing too much about dsmc. I have checked and you should be able to get results for flow in a pipe of the size you gave within a day or two. OpenFoam has a DSMC module that can be used for parallel processing and 3D problems.

Hope it helps!

artemiss1984 · July 22, 2010, 16:55

Dear friends.

I am looking for openfoam 1.7 tutorial or user guide for dsmc simulation.I checked the openfoam site and any other related sites, but unfortunately I could not download it (because of our blocked Ip).Can you help me to obtain this? thanks

July 1, 2010, 17:54	Need advice on softwares working for dilute gas flow	#1
Mason New Member Join Date: Jul 2010 Posts: 2 Rep Power: 0	Hello everyone, I'm currently working on a project that involves dilute/rarefied gas flow in a pipe. The inlet pressure is about 1-10 Pa, and the Kundsen number of the flow is around 0.1-0.2, as my estimation. Clearly, the flow is in the slip flow regime or transitional flow regime. To my knowledge, CFD using N-S equations might still work in this regime, with some tweaks. My question is, what is the best commercial CFD software out there that will work for my project? I've tried Comsol Multiphysics, using both incompressible N-S mode/weakly compressible N-S with no-slip/slip boundary conditions, but the modeling results do not match the experiements. I wonder if there is any other CFD software that will work better for dilute gas flow. Or, do I have to use DSMC? The problem with DSMC is that the scale of my model is pretty big, and a 3-D DSMC modeling might be too big to handle. Thank you for your suggestion/advice.

July 19, 2010, 10:40	Suggestion	#4
Andre van der Walt New Member Andre van der Walt Join Date: Jun 2010 Posts: 5 Rep Power: 16	Hi Mason I think DSMC is probably the best method to go. Can the simulation be set up as an axi-symmetric problem? If so you can use the DS2V code of Bird fairly easy, without worrying about not knowing too much about dsmc. I have checked and you should be able to get results for flow in a pipe of the size you gave within a day or two. OpenFoam has a DSMC module that can be used for parallel processing and 3D problems. Hope it helps!

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July 16, 2010, 05:55		#2
Andre van der Walt New Member Andre van der Walt Join Date: Jun 2010 Posts: 5 Rep Power: 16	Hi Mason, how big is the regime that you would like to model?

July 22, 2010, 16:55		#5
artemiss1984 Member Join Date: Apr 2009 Posts: 38 Rep Power: 17	Dear friends. I am looking for openfoam 1.7 tutorial or user guide for dsmc simulation.I checked the openfoam site and any other related sites, but unfortunately I could not download it (because of our blocked Ip).Can you help me to obtain this? thanks