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2D higly underexpanded jet

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Old   April 17, 2019, 11:46
Smile 2D higly underexpanded jet
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Gianmario Ledda
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Hi, I work for my master thesis and I must study an higly underexpanded jet due to an accidental release of methane from a pressurized pipe.
I try to work with a 2D geometry but I have different results from 3D to 2D geometry and I don't understand why.
In 3d I have a result in according with the theory, meanwhile in 2D I'm not able to reach it.
I use Fluent 18.2
I use a convergent nozzle, with a pressure inlet
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Old   April 17, 2019, 12:11
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What are we looking for?


The nozzle contours are different.


Even if the contours are the same, you are doing a 2D slot versus (we can't see it but presumably) a 3D axissymmetric nozzle.


Maybe an apples to apples comparison rather than an apples to elephant comparison would be more helpful?
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Old   April 17, 2019, 12:31
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Tank you for the answer LuckyTran. I already fix the contours of the nozzle and now are the same, but my problem is the same. I have my 3D problem, but because I have a radial simmetry I decide to study the problem in 2D, and according with the theory the result must be the same that I have reached in 3D. So the theory says that I can study my problem in 2D and the velocity field must be similar to 3D image. But I'm not able to do this.
Do you think that I must study also my 2D problem like axissymetric?
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Old   April 17, 2019, 12:57
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LuckyTran, I understand and solve my problem, thank you so much.
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Old   April 28, 2019, 06:18
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akash gupta
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Hello

I am working on CD Nozzle (2D Model) simulation in ANSYS Fluent- (real time project). The Inlet conditions are: Pressure =0.6mpa and Temperature = 588.6 k. Expected outlet Temperature is around 350 k.
As I am trying to simulate in Fluent, after few iterations, I am getting a reverse flow on pressure inlet and pressure outlet and there is also a reduce in time step due to excess temperature change.
How can I resolve these kind of errors that will help me to in the simulation.
can you help me
plz
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