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Old   February 12, 2003, 18:12
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Robi
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Hello,

I have written a code for compressible (varable density, ideal gas for example) flow in a pipe using SIMPLE. When the condition is isothermal I observe no problem. When I include the energy equation in the model (inlet temperature is fixed and I set the pipe wall temperature equal to Ta<T_inlet) all my problems start. The steady state solution is correct while in the transient part I observe negative pressure, back flow. Is is because of initial condition? I am sure the energy code is correct. The major problem is for the transient part. Can anyone help me with this? Is there any free code for such a simple problem?

Many many thanks for your help.
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Old   February 13, 2003, 01:27
Default Re: Simple question
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Reader
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Where is your simple question?
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Old   February 13, 2003, 01:51
Default Re: Simple question
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Robi
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Sorry it seems part of the message was somehow omitted.

So here is the question one more time:

I have written a code for compressible (variable density, ideal gas for example) flow in a pipe using SIMPLE. When the condition is isothermal I observe no problem. When I include the energy equation in the model (inlet temperature is fixed and I set the pipe wall temperature equal to Ta< T_inlet) in the transient result I observe negative pressure (with respect to outlet pressure) and some back flow. my question: Do you think the back flow and negative pressure is due to my incorrect (incompatible) boundary condition? Is there any free code similar to this problem so I can verify or compare the results? Many many thanks for your help.
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