Conjugate Heat Transfer Turbulence Model

buckngnr11 · October 28, 2020, 09:35

I'm fairly new to conjugate heat transfer modeling. I'm modeling an impinging jet on a flat plate. I set the mass flow rate and temperature in the pipe from some experimentally measured data. I am seeing though that the plate (metal) temperature changes SIGNIFICANTLY depending on the RANS model I choose. I understand their being differences between different models and generally I'd use k-omega SST for this type of flow, but when I switch between K omega SST and k-epsilon with enhanced wall treatment, the backside temperatures of the plate change by about 20%. It makes no sense to me whatsoever that it would be that dramatic. My y plus values are well below one throughout the domain. Is this par for the course when it comes to heat transfer with turbulence? Anyone have any suggestions for the "best" model for an impinging jet flow for heat transfer?

Thanks!

buckngnr11 · October 28, 2020, 09:37

By the way my Reynolds number is somewhere in the 3000-4000 range so that adds some complication as it's smack dab in the transitional regime. Not sure if this really makes a difference

sapujapu · October 29, 2020, 05:04

Yes, turbulence models have a huge effect on heat transfer, especially when you compare k-omega-SST and k-epsilon. From what I remember from the literature, k-epsilon is not recommended for simulations like this. Have a look at this paper:

Heat Transfer Enhancement by Turbulent Impinging Jet with Jet's Velocity
Field Excitations Using OpenFOAM, ICFD 2017 : 19th International Conference
on Fluid Dynamics Sydney, Australia

There, they compared turbulence models for an impinging jets. I'm sure there are additional papers about the topic out there.

October 28, 2020, 09:35	Conjugate Heat Transfer Turbulence Model	#1
buckngnr11 Member j Join Date: Apr 2020 Posts: 34 Rep Power: 0	I'm fairly new to conjugate heat transfer modeling. I'm modeling an impinging jet on a flat plate. I set the mass flow rate and temperature in the pipe from some experimentally measured data. I am seeing though that the plate (metal) temperature changes SIGNIFICANTLY depending on the RANS model I choose. I understand their being differences between different models and generally I'd use k-omega SST for this type of flow, but when I switch between K omega SST and k-epsilon with enhanced wall treatment, the backside temperatures of the plate change by about 20%. It makes no sense to me whatsoever that it would be that dramatic. My y plus values are well below one throughout the domain. Is this par for the course when it comes to heat transfer with turbulence? Anyone have any suggestions for the "best" model for an impinging jet flow for heat transfer? Thanks!

October 28, 2020, 09:37	Reynolds	#2
buckngnr11 Member j Join Date: Apr 2020 Posts: 34 Rep Power: 0	By the way my Reynolds number is somewhere in the 3000-4000 range so that adds some complication as it's smack dab in the transitional regime. Not sure if this really makes a difference

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October 29, 2020, 05:04		#3
sapujapu New Member Join Date: Feb 2020 Posts: 10 Rep Power: 6	Yes, turbulence models have a huge effect on heat transfer, especially when you compare k-omega-SST and k-epsilon. From what I remember from the literature, k-epsilon is not recommended for simulations like this. Have a look at this paper: Heat Transfer Enhancement by Turbulent Impinging Jet with Jet's Velocity Field Excitations Using OpenFOAM, ICFD 2017 : 19th International Conference on Fluid Dynamics Sydney, Australia There, they compared turbulence models for an impinging jets. I'm sure there are additional papers about the topic out there.