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Old   May 28, 2013, 04:33
Post Steady State Jet Impingement
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Smaras
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Hello,

I have problem in the start. I am doing this simulation of supersonic jet impingement of air (incompressible ideal) on a flat plate. My settings for simulation are as follows:

operating pressure: 101325 pas

Pressure based+ Steady

1. Model:
Energy+ Kw SST

2. Boundary Condition:
Inlet: velocity input (727.07 m/s)
Outlet: Pressure Outlet 0 gauge pressure

3. Solution Method:
Scheme: Simple
Pressure: Presto
URF: Pressure 0.3 Density/BF 0.5 Momentum 0.5 Tke/SDR 0.8 TV/Energy 1


Now i cannot go further then 20 iterations and its give an error of floating point error.

temperature limited to 1.000000e+00 in 492 cells on zone 12 in domain 1
temperature limited to 5.000000e+03 in 10643 cells on zone 12 in domain 1

turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 21 cells
13 6.8784e+03 9.8749e-01 6.2555e-01 3.9413e+07 1.8524e+01 4.4528e-02 3.2878e+06 5:49:40 99987
temperature limited to 1.000000e+00 in 2273 cells on zone 12 in domain 1
temperature limited to 5.000000e+03 in 16155 cells on zone 12 in domain 1

turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 342 cells
14 4.8991e+07 8.0444e-01 1.9110e-01 1.1793e+10 3.9392e+00 9.6625e-01 2.0071e+06 4:39:44 99986

Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature temperature limited to 1.000000e+00 in 6325 cells on zone 12 in domain 1

Primitive Error at Node 0: floating point exception

Primitive Error at Node 1: floating point exception

Primitive Error at Node 2: floating point exception

Primitive Error at Node 3: floating point exception

Primitive Error at Node 4: floating point exception


Please if anybody knows about this. Would be thankful for the help.

Last edited by Smaras; May 28, 2013 at 04:44. Reason: forgot some details
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Old   May 29, 2013, 09:40
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Jim Knopf
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Hi,

try to deactivate the second order gradients for the temperature.

(rpsetvar 'temperature/secondary-gradient? #f)
(rpsetvar 'temperature/shell-secondary-gradient? #f)


Greetz
Jim
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Old   May 30, 2013, 02:05
Default Error resolved
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Parampreet Singh
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All you need to do is to adjust the under relaxation factors for various field. Its in the solve menu...

Hope it helps

regards,
prince
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Old   May 31, 2013, 04:13
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Quote:
Originally Posted by JimKnopf View Post
Hi,

try to deactivate the second order gradients for the temperature.

(rpsetvar 'temperature/secondary-gradient? #f)
(rpsetvar 'temperature/shell-secondary-gradient? #f)


Greetz
Jim
Thanks Jim for replying but by that time i was away and yesterday was holiday in my country.

I have question regarding this isnt used for tetra mesh. Since I am using hexa meshing.

Regards,
Smaras

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Old   May 31, 2013, 04:14
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Quote:
Originally Posted by Prince Jassal View Post
All you need to do is to adjust the under relaxation factors for various field. Its in the solve menu...

Hope it helps

regards,
prince
Thanks Prince,

Did tried that and now comparing my results with compressible flow....with same configuration.

Regards,
Smaras
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Old   June 1, 2013, 04:01
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Jim Knopf
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Hi Smaras,

am I right that you are trying to simulate a supersonic jet with incompressible air? I'm wondering if supersonic flows can be simulated that way, can they?
Did you try to run compressible simulations?

Anyhow impinging jets are a bit nasty. In my cases of subsonic flows we experienced that the RNG and the Realizable k-epsilon model gave a better stability. So you might try a different turbulence model.

Greetz
Jim
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Old   June 4, 2013, 04:58
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Smaras
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Quote:
Originally Posted by JimKnopf View Post
Hi Smaras,

am I right that you are trying to simulate a supersonic jet with incompressible air? I'm wondering if supersonic flows can be simulated that way, can they?
Did you try to run compressible simulations?

Anyhow impinging jets are a bit nasty. In my cases of subsonic flows we experienced that the RNG and the Realizable k-epsilon model gave a better stability. So you might try a different turbulence model.

Greetz
Jim
Hello Jim,

yes you are right, i am working on simulating jet with in-compressible air. And till now i am getting good results. As i am counter checking with previous research of Annie Nordquist and Morshed Alam et all research papers for compressible flows.
And no for me KE or even realizable isn't working, and again my supervisors arentz fond of KE
Now want to find the BC for the same flow rate and pressure profile at the interface. I have some how get some of my result pretty close as my mistake was when i was doing in SST it automatically checked viscous heating which in my case wasn't applicable.

But still i am open for suggestions.

Best Regards
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