DSMC Fields Meaning

eemdee · April 5, 2017, 16:05

Hi Foamers,

I'm running the dsmcFoam tutorial 'wedge15Ma5' to better understand the dsmcFoam solver. I'm trying to understand some of the output. I've read the following file which helps inform my view of the different fields

https://github.com/OpenFOAM/OpenFOAM...thods/dsmcFoam

(1) What is the difference between dsmcRhoN and rhoN? How can I set the conditions on one without it affecting the other? My understanding is that dsmcRhoN is only used for calculating the result of particles hitting the boundary, is this true? Wouldn't the simulation only give a physical answer if they agree?

(2) I've also read in other (albeit older) threads that you can only specify a single number density for all patch faces when using dsmcFoam. Is this still true in openfoam4's dsmcFoam? It certainly doesn't seem to be the case when I play around with this tutorial but I also still don't understand the difference between dsmcRhoN and rhoN so I could be misinterpreting.

(3) The boundary conditions for these densities don't seem to affect the simulation that much. Is there a reason for this?

An answer to any or all of these questions would be greatly appreciated. Even links to older threads that could help set me in the right direction. I couldn't find anything in the forums that touch on this topic but it seems very unclear. Sorry if this is answered elsewhere and/or obvious.

vighnesh.j · September 30, 2017, 01:17

Hi Eric Emdee,

I am solving the gas flows in micro channels and so i am using the dsmcFoam solver.
From my observations and the solvings, the dsmcRhoN means the number of dsmc particles that are inserted,and the RhoN indicates the number of gas particles inserted.

The difference between the dsmc particles and gas particles is that ,the former can have any number of the latter.That is the first assumption that is taken for using the solver and the problem is solved.

Hope this helped you !!!!

April 5, 2017, 16:05	DSMC Fields Meaning	#1
eemdee New Member Eric Emdee Join Date: Mar 2017 Posts: 6 Rep Power: 9	Hi Foamers, I'm running the dsmcFoam tutorial 'wedge15Ma5' to better understand the dsmcFoam solver. I'm trying to understand some of the output. I've read the following file which helps inform my view of the different fields https://github.com/OpenFOAM/OpenFOAM...thods/dsmcFoam (1) What is the difference between dsmcRhoN and rhoN? How can I set the conditions on one without it affecting the other? My understanding is that dsmcRhoN is only used for calculating the result of particles hitting the boundary, is this true? Wouldn't the simulation only give a physical answer if they agree? (2) I've also read in other (albeit older) threads that you can only specify a single number density for all patch faces when using dsmcFoam. Is this still true in openfoam4's dsmcFoam? It certainly doesn't seem to be the case when I play around with this tutorial but I also still don't understand the difference between dsmcRhoN and rhoN so I could be misinterpreting. (3) The boundary conditions for these densities don't seem to affect the simulation that much. Is there a reason for this? An answer to any or all of these questions would be greatly appreciated. Even links to older threads that could help set me in the right direction. I couldn't find anything in the forums that touch on this topic but it seems very unclear. Sorry if this is answered elsewhere and/or obvious. vighnesh.j likes this.

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September 30, 2017, 01:17		#2
vighnesh.j New Member Jujjavarapu Vighnesh Join Date: Apr 2017 Posts: 9 Rep Power: 9	Hi Eric Emdee, I am solving the gas flows in micro channels and so i am using the dsmcFoam solver. From my observations and the solvings, the dsmcRhoN means the number of dsmc particles that are inserted,and the RhoN indicates the number of gas particles inserted. The difference between the dsmc particles and gas particles is that ,the former can have any number of the latter.That is the first assumption that is taken for using the solver and the problem is solved. Hope this helped you !!!!