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simulation with ideal gas material properties

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Old   February 28, 2006, 08:03
Default simulation with ideal gas material properties
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Ana
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Hi, i am simulating the airflow over a diffusor in the compressor of a turbocharger with fluent 3d.

I select the option density =ideal gas in material properties, and i dont know how to initialize the problem.

I have the following boundary conditions:inlet massflow, and the outlet pressure.

I already tried to initialize with both, massflow and pressure outlet, with pressureoutlet and introducing my own values. I always get this error:

divergence detected in AMG solver

If i use the constant density model i dont find any problem.

if anyone can help me, i would thank you

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Old   February 28, 2006, 08:04
Default Re: simulation with ideal gas material properties
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Ana
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the error was divergence of temperature. Sorry
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Old   February 28, 2006, 08:17
Default Re: simulation with ideal gas material properties
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kafka
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Usually when dealing with ideal gas, I initially disable the energy equation in Solve/Controls/Solution. Once the problem tends to converge, I enable the energy again. This procedure is also recommended in the Fluent manual and it works most of the time.
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Old   March 1, 2006, 17:27
Default Re: simulation with ideal gas material properties
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Chris Bailey
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I have had a similar problem and substituted my own polynomials for the gas properties, which eliminated the divergence error. Also, for some reason I don't understand (and have a request in to tech support for), Fluent's model for air seems to give half the conductivity and 1/3 the specific heat that it should.
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