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Old   March 18, 2010, 06:25
Default User Defined Density
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Hi everybody!

my problem is the compressibility of my fuel cause of the high pressure (up to 1600bar) so i need to implement a density which depends on the pressure.
How can I do this? I've a multiphase mixture with Dodecane Liquid/Vapour.
i have this formula for the density: density(25°C)=829 + 0.0123*pressure(inlet) + 0.000123*pressure²(inlet)
Can anybody help me? Maybe a field function? But i never wrote something like that...

Thanks for any help!
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Old   March 18, 2010, 13:46
Vinicius Girardi
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First of all you have to choose User Defined Density on the equation of state. After that, in the density propeties, select field function.
If you will use the inlet pressure as reference in you formula, you have to create a report of the inlet pressure. You can rename it to "Inlet Pressure". (note, this name will be important)
Now you can create a field function, on the node field functions in the tools node. In the new field function properties, adjust the dimensions to mass/volume and in the definition you can paste this:

829 + 0.0123*$InletPressureReport + 0.000123*pow($InletPressureReport,2)

Now choose your field function in the density node.

Let me know if you have more questions.

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