Problem with modelling of the jet flow

digger · January 23, 2021, 18:20

Hi,

I am using RANS with k-e realizable model in simulation of the jet flow. I am facing the problem of too much diffusivity. The downstream profiles (lines) are far from reality (dots). Any advices what can be done to improve accuracy of the results?

For me the momentum transport in radial directions is too high at downstream locations. May it be caused by a poor accuracy if the inlet velocity profile? Also, I define Ti and turbulence length scale at the inlet. I found that the results are extremely sensitive to the change of the turbulence length scale but mostly close to the inlet.

Of course, I am not asking anyone for solving the problem for me but I would be thankful for any advices because I got stuck.

Thanks in advance

https://i.postimg.cc/Gts6T2vb/1.png
https://i.postimg.cc/hhW6LB0T/2.png
https://i.postimg.cc/qRF97nhm/3.png

FMDenaro · January 23, 2021, 20:22

Are you comparing your solutions to some experimental result?

January 23, 2021, 18:20	Problem with modelling of the jet flow	#1
digger New Member Join Date: Jan 2021 Posts: 18 Rep Power: 5	Hi, I am using RANS with k-e realizable model in simulation of the jet flow. I am facing the problem of too much diffusivity. The downstream profiles (lines) are far from reality (dots). Any advices what can be done to improve accuracy of the results? For me the momentum transport in radial directions is too high at downstream locations. May it be caused by a poor accuracy if the inlet velocity profile? Also, I define Ti and turbulence length scale at the inlet. I found that the results are extremely sensitive to the change of the turbulence length scale but mostly close to the inlet. Of course, I am not asking anyone for solving the problem for me but I would be thankful for any advices because I got stuck. Thanks in advance https://i.postimg.cc/Gts6T2vb/1.png https://i.postimg.cc/hhW6LB0T/2.png https://i.postimg.cc/qRF97nhm/3.png

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January 23, 2021, 20:22		#2
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,768 Rep Power: 71	Are you comparing your solutions to some experimental result?