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Backwards Flow in Impinging Jet Inlet

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Old   June 29, 2022, 15:08
Question Backwards Flow in Impinging Jet Inlet
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I am trying to resolve an issue in a slot jet model, where I am finding the flow is partially reversing and travelling up the nozzle instead of travelling entirely away from the inlet.

My case is 2D, symmetric and incompressible, with a heated wall. I tried turning off physics like compressibility and heat transfer, though none of these corrected the flow reversal. I also don't believe the issue is mesh-related because my mesh is sufficiently fine to resolve the boundary layer according to my esimates. Also, the outlet was moved away from the inlet in an attempt to reduce backflow.

The current boundary conditions I am using are a total pressure outlet and a mass flow rate inlet.

One thing I haven't tried yet is adding a fillet to the sharp corner at the inlet's end. I'm unsure if this will make a difference.

Has anyone encountered an issue like this previously? If so do, do you have any suggestions on how I may fix it? Thanks.
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Old   June 30, 2022, 10:54
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Vigneshwar Ravisankar
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Hi,

Can you details of the case setup, its tough to explain with limited information. Need to look into the 3D outputs and the case setup in detail before commenting on what's happening.
You can share it with our support:
support@convergecfd.com(US)
supportEU@convergecfd.com(EU)
support.in@convergecfd.com(IN)
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Old   July 13, 2022, 08:09
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Quote:
Originally Posted by rvigneshwar View Post
Hi,

Can you details of the case setup, its tough to explain with limited information. Need to look into the 3D outputs and the case setup in detail before commenting on what's happening.
You can share it with our support:
support@convergecfd.com(US)
supportEU@convergecfd.com(EU)
support.in@convergecfd.com(IN)
I did submit an email to support.

The case I am studying is an L shaped flow: inlet at the top and outlet at the bottom right, with symmetry across the midline.

I have since tried adding fixed embedding to the inlet, and I am still seeing non-physical results. The velocity magnitude field looks checkered with high and low magnitude cells near the start of the inlet. Perhaps it is not completely converged, but I still didn't see this kind of field in my set up cases - they showed a uniform and high velocity within the inlet.

I'm not sure what else to try at this point. Maybe I can try assigning a velocity profile to the inlet.
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Old   July 14, 2022, 10:09
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Vigneshwar Ravisankar
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Thanks, The support team will respond to you at earliest.
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