Turbulence Model in axisymmetric nozzle simulation

cric92 · May 21, 2013, 03:03

Hi

I am simulating an axisymmetric nozzle. I have an issue with which turbulence model to use. Currently I am using standard K-epsilon and i am not getting any shock wave inside the nozzle. When I switch to SST K omega i get shock wave in the flow.

I would like to ask which is the recommended turbulence model for these type of flow

oj.bulmer · May 21, 2013, 06:27

By intuition, std k-eps model is diffusive and hence may smear out the sharp gradients responsible for shocks. Have you tried realizable model? It is deemed to be good in modelling jets.

OJ

cric92 · May 22, 2013, 12:50

Yes, Just tried realizable.. it also shows a shock wave

NozzleNoobie · September 4, 2017, 13:11

Hi, could i ask you what do you mean by diffusive?

Arjun_kalkur · September 4, 2017, 17:57

K-epsilon does not behave well in large pressure gradient, one like shocks, I'd suggest to stick with SST. By diffusive he means the behavior of the solver, like for eg:- Picks the information from the succeeding nodes and moves forward

NozzleNoobie · September 5, 2017, 00:35

I see that the SST k-omega model is more suitable for compressible flow into a nozzle for its good behaviour in adverse pressure gradients (shock) and separating flow. Thank you for your help!

May 21, 2013, 03:03	Turbulence Model in axisymmetric nozzle simulation	#1
cric92 New Member Join Date: Dec 2012 Posts: 11 Rep Power: 14	Hi I am simulating an axisymmetric nozzle. I have an issue with which turbulence model to use. Currently I am using standard K-epsilon and i am not getting any shock wave inside the nozzle. When I switch to SST K omega i get shock wave in the flow. I would like to ask which is the recommended turbulence model for these type of flow

September 4, 2017, 17:57		#5
Arjun_kalkur New Member Arjun Kalkur Join Date: Sep 2017 Posts: 12 Rep Power: 9	K-epsilon does not behave well in large pressure gradient, one like shocks, I'd suggest to stick with SST. By diffusive he means the behavior of the solver, like for eg:- Picks the information from the succeeding nodes and moves forward NozzleNoobie and TommyM like this.

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May 21, 2013, 06:27		#2
oj.bulmer Senior Member OJ Join Date: Apr 2012 Location: United Kindom Posts: 473 Rep Power: 20	By intuition, std k-eps model is diffusive and hence may smear out the sharp gradients responsible for shocks. Have you tried realizable model? It is deemed to be good in modelling jets. OJ

May 22, 2013, 12:50		#3
cric92 New Member Join Date: Dec 2012 Posts: 11 Rep Power: 14	Yes, Just tried realizable.. it also shows a shock wave

September 4, 2017, 13:11		#4
NozzleNoobie New Member Jeff Yam Join Date: Sep 2017 Posts: 11 Rep Power: 9	Hi, could i ask you what do you mean by diffusive?

September 5, 2017, 00:35		#6
NozzleNoobie New Member Jeff Yam Join Date: Sep 2017 Posts: 11 Rep Power: 9	I see that the SST k-omega model is more suitable for compressible flow into a nozzle for its good behaviour in adverse pressure gradients (shock) and separating flow. Thank you for your help!