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-   -   Energy Source Help! (http://www.cfd-online.com/Forums/fluent/38357-energy-source-help.html)

 Andrew Clark October 24, 2005 14:17

Energy Source Help!

I just want to clarify that I am using the Energy Source function correctly (the option under Fluids)

I am attempting to take a tube with air flowing through it and inject a fuel into the flow at a certain mass, momentum and temperature. Note that I am using an inviscid coupled solver, so I cannot fix the temperature which I would have liked to have done

I have figured out how to set the mass and momentum correctly as they are clearly stated in the user guide, however I am having problems setting the energy source correctly.

It is my understanding that for inviscid flow:

E = h + p/rho

So for example if my temperature is 750K, the Cp is 1000, standard state temperature is 298.15K and the standard state enthalpy is 0, I can find h from:

h = 1000*(750-298.5) + 0

Where would I get the pressure and density from? Are these the reference values, or the conditions of the source? The reason I question this, when I change the reference values, this has an effect on the final temperature of the source (that being once a cooler air has flowed over it)?

Also is there anyway to verify I set the conditions correctly in Fluent, because when the air flows through the tube (at 200K), it also flow over the source therefore changing the temperature so I have no way of checking to make sure my source is in fact at 750K.

Thank you

Andrew

 Sherry October 24, 2005 14:39

Momentum Equation for Porous Media

I tried to write down the governing equations for multi-phase flow in a porous medium. Does anybody know whether the velocity used in equation (7.19-30) of users guide is the physical velocity. If so, I think there are some problems for this equation compared to other models we usually use. Can I use the UDF to define the whole momentum equation by myself?

Thanks a lot. I hope I can find someone who also use fluent to simulate the porous media and can give me some advices about it.

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