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-   -   Which macro yields the absolute pressure value? (https://www.cfd-online.com/Forums/fluent-udf/151558-macro-yields-absolute-pressure-value.html)

shivakumar April 13, 2015 05:43

Which macro yields the absolute pressure value?
 
Hi,
From the solution data it is possible to obtain absolute pressure value at each node or cell center. In FLUENT manual I couldn't find the macro for absolute pressure.
Which macro yields the absolute pressure value.?

Thanks in advance

CeesH April 13, 2015 05:59

Isn't C_P(c,t) the absolute pressure?

If it is the relative, add the operating pressure to it and you're good to go right?

shivakumar April 13, 2015 06:07

Thanks for the reply.

I guess it is a static pressure value but I'm not sure..

But in the solution data, there are absolute, total, static pressure, etc values are available so only confused to access absolute pressure.
:confused:

CeesH April 13, 2015 06:46

Maybe you want to check out the FLUENT user manual, section 7.14.

All pressures that you specify and all pressures computed or reported by ANSYS Fluent are gauge pressures.

So I'd guess the pressure reported by the macro is indeed a gauge pressure.

Then:
P_abs = P_operating + P_gauge. So, to get the absolute pressure, simply add the macro to the operating pressure.

To differentiate a bit more clear:

Static pressure: The static gauge pressure
Dynamic pressure: Velocity pressure (0.5*density*velocity)
absolute pressure: total static pressure; the gauge + operating pressure
total pressure: dynamic + static gauge pressure

Does this answer your question?

shivakumar April 13, 2015 11:23

U have solved my doubt. I got it. Thank you very much ..:):):):)


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