Turbulence Models

oliveira1820 · May 23, 2018, 02:49

Hello to you all again

In my system I have a water cooling system with 0,2 l/s where the water receives the heat from the solids around, which gets to "turbulent" velocities. (Reynolds number).

And a container with heated water which evaporates and gets really fast and hot.

I´m tryind to decide wich turbulence models should I use for each situatuion and I can´t get any conclusion. Do you have any hint which one fits better each situation in particular?

Best regards and thanks!!

urosgrivc · May 23, 2018, 04:15

personaly I would use SST model for the firs case, beacouse you have heat transfer so you need acurate near wall modeling and because it combines omega and epsilon models with 2 blending functions. You can also complicate and add additional 2 equations for (transitional turbulence) intermitency and rethetat, so the flow can be laminar and turbulent (laminar usualy in the proximity of the wals)

For the second case I am not sure as i dont have experience with evaporation in cfx

siw · May 23, 2018, 04:16

Shear Stress Transport (SST) with the default automatic wall treatment is a good place to start for RANS/URANS simulations. Only once you see the results can you judge if another model should be used instead or if you need to go with a RSM or scale-resolving method.

Gert-Jan · May 23, 2018, 04:25

SST is my working horse in these cases.
Make sure Y+ is around 1 where Prandtl is high (approx 7 at cooling side?).

oliveira1820 · May 24, 2018, 01:06

I will use SST and see if I got convergence problems and if it doesn´t corresponds to the experimetnal values I´l try another.

Thank you very much guys!!!! Good work to you all

May 23, 2018, 02:49	Turbulence Models	#1
oliveira1820 Senior Member Pedro Oliveira Join Date: Feb 2018 Location: Portugal Posts: 109 Rep Power: 8	Hello to you all again In my system I have a water cooling system with 0,2 l/s where the water receives the heat from the solids around, which gets to "turbulent" velocities. (Reynolds number). And a container with heated water which evaporates and gets really fast and hot. I´m tryind to decide wich turbulence models should I use for each situatuion and I can´t get any conclusion. Do you have any hint which one fits better each situation in particular? Best regards and thanks!!

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May 23, 2018, 04:15		#2
urosgrivc Senior Member urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 365 Rep Power: 11	personaly I would use SST model for the firs case, beacouse you have heat transfer so you need acurate near wall modeling and because it combines omega and epsilon models with 2 blending functions. You can also complicate and add additional 2 equations for (transitional turbulence) intermitency and rethetat, so the flow can be laminar and turbulent (laminar usualy in the proximity of the wals) For the second case I am not sure as i dont have experience with evaporation in cfx

May 23, 2018, 04:16		#3
siw Senior Member Stuart Join Date: Jul 2009 Location: Portsmouth, England Posts: 733 Rep Power: 25	Shear Stress Transport (SST) with the default automatic wall treatment is a good place to start for RANS/URANS simulations. Only once you see the results can you judge if another model should be used instead or if you need to go with a RSM or scale-resolving method.

May 23, 2018, 04:25		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	SST is my working horse in these cases. Make sure Y+ is around 1 where Prandtl is high (approx 7 at cooling side?).

May 24, 2018, 01:06		#5
oliveira1820 Senior Member Pedro Oliveira Join Date: Feb 2018 Location: Portugal Posts: 109 Rep Power: 8	I will use SST and see if I got convergence problems and if it doesn´t corresponds to the experimetnal values I´l try another. Thank you very much guys!!!! Good work to you all