Ejection and reactingFoam

Waggy · March 18, 2018, 06:01

Hello, foamers.

I want to calculate ejection of helium's jet in surrounding air. I need to be able to change densities of gases in surrounding air and solver must get fields of densities of components.

What solver should I use? I tried reactingFoam without chemical reactions, but there were problems with heat transfer and it was difficult to handle them. Maybe, there is a more appropriate solver for that task?

piu58 · March 18, 2018, 09:39

If the jet is well below the Mach number you may try interFoam.

tomf · March 20, 2018, 05:13

Hi,

interFoam will not work, since it is a multiphase solver, while multispecies is needed in this case. Also interFoam expects a sharp interface, while that is not the case with helium in air.

I think the rhoReactingFoam solver may be an option? I do agree that the Mach number is important and may cause convergence issues, especially if there are shocks and other transsonic effects.

Regards,
Tom

Waggy · March 20, 2018, 08:20

Thanks everyone!

Waggy · March 20, 2018, 08:23

Tomf, what is the rhoReactingFoam? What the difference between it and reactingFoam?

I just tried rhoReactingFoam but it gives the same problem as the reactingFoam. It says that temperature is out of range. I found that it depends on Courant number, but I didn't find any valid solution for that.

I think reactingFoam is trying to solve heat transfer, because it was created for simulation of combustion processes, but I don't want it to do that. So, I think there must be appropriate solver for multi component mixture. ANSYS can do that very easy! Why OpenFOAM has so many problems with that?

tomf · March 21, 2018, 03:22

Hi,

The difference is in the way the thermodynamics is set-up. For rhoReactingFoam it is based on the density field. Look at the user guide for more information.

Heat transfer will be happening if fluids with different enthalpy mix. Your problem may be from schemes, mesh quality, boundary conditions. We do not know what leads to your error if you do not give information about the exact set-up.

Regards,
Tom

Waggy · March 24, 2018, 03:41

Thank you for help!
I solved my problem in another way (with using multyphaseInterFoam).
I'm gonna present my result in another thread

March 18, 2018, 06:01	Ejection and reactingFoam	#1
Waggy New Member Sergey Join Date: Feb 2018 Posts: 8 Rep Power: 8	Hello, foamers. I want to calculate ejection of helium's jet in surrounding air. I need to be able to change densities of gases in surrounding air and solver must get fields of densities of components. What solver should I use? I tried reactingFoam without chemical reactions, but there were problems with heat transfer and it was difficult to handle them. Maybe, there is a more appropriate solver for that task?

March 18, 2018, 09:39		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	If the jet is well below the Mach number you may try interFoam. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

March 20, 2018, 05:13		#3
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 638 Rep Power: 32	Hi, interFoam will not work, since it is a multiphase solver, while multispecies is needed in this case. Also interFoam expects a sharp interface, while that is not the case with helium in air. I think the rhoReactingFoam solver may be an option? I do agree that the Mach number is important and may cause convergence issues, especially if there are shocks and other transsonic effects. Regards, Tom piu58 likes this.

March 20, 2018, 08:20		#4
Waggy New Member Sergey Join Date: Feb 2018 Posts: 8 Rep Power: 8	Thanks everyone!

March 20, 2018, 08:23		#5
Waggy New Member Sergey Join Date: Feb 2018 Posts: 8 Rep Power: 8	Tomf, what is the rhoReactingFoam? What the difference between it and reactingFoam? I just tried rhoReactingFoam but it gives the same problem as the reactingFoam. It says that temperature is out of range. I found that it depends on Courant number, but I didn't find any valid solution for that. I think reactingFoam is trying to solve heat transfer, because it was created for simulation of combustion processes, but I don't want it to do that. So, I think there must be appropriate solver for multi component mixture. ANSYS can do that very easy! Why OpenFOAM has so many problems with that?

March 21, 2018, 03:22		#6
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 638 Rep Power: 32	Hi, The difference is in the way the thermodynamics is set-up. For rhoReactingFoam it is based on the density field. Look at the user guide for more information. Heat transfer will be happening if fluids with different enthalpy mix. Your problem may be from schemes, mesh quality, boundary conditions. We do not know what leads to your error if you do not give information about the exact set-up. Regards, Tom

March 24, 2018, 03:41		#7
Waggy New Member Sergey Join Date: Feb 2018 Posts: 8 Rep Power: 8	Thank you for help! I solved my problem in another way (with using multyphaseInterFoam). I'm gonna present my result in another thread