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-   -   Enthalpy calculation (https://www.cfd-online.com/Forums/su2/229998-enthalpy-calculation.html)

WilliamH September 3, 2020 05:14

Enthalpy calculation
 
Hi everyone,
I have successfully found a solution for my Mach 5 scramjet inlet and displayed the results in ParaView. I have values for temperature, density and pressure. I would like to calculate the enthalpy.
Is there an easy way to do so in ParaView using the calculator?
If not, can SU2 calculate the enthalpy?
Thanks!

aero_amit September 3, 2020 09:46

You can use calculator in ParaView to do so.
Make use of pressure, density. Get velocity components by dividing momentum with density and use the enthalpy formula..

WilliamH September 4, 2020 04:39

Thanks for the help! Would you mind detailing the steps? What formula for entropy are you using?

aero_amit September 6, 2020 08:08

Hi William,

Your first post mentioned Enthalpy so I am assuming that as a variable to be computed.

In ParView, press Calculator and compute a variable with any name you like (let us say Vel_vec) and in formula - Momentum/Density

Again highlight this Calculator1 and compute Total specific enthalpy (Hs or whatever name you like) with (let's say 2D case) formula -
Pressure*3.5/Density+0.5*(Vel_vec_X*Vel_vec_X+Vel_vec_Y*Vel_vec _Y)
(here 3.5 is for gamma/(gamma-1)).

Best
Amit

WilliamH March 31, 2021 05:31

Hi, sorry for only replying now.
Your method worked well but could you explain how you derived this formula? I've been trying to find similar formula on the Internet but I cannot seem to find it.
I also tried to check the units but they didnt seem to add up. Should the total specific enthalpy be in J/kg?
Thanks
William

aero_amit April 1, 2021 07:04

Hi WilliamH, You can find it in most of the text books (Gas Dynamics, CFD).

Basically H=h+V^2/2

here - h= CpT = g*RT/(g-1) = 3.5*P/Rho for g=1.4 & V^2=u^2+v^2+w^2 in 3D.

Yes it is total specific enthalpy and unit is J/kg or m^2 sec^-2.

Here my primary intention was to convey the procedure of calculating a variable of interest in ParaView from available dataset.

Best
Amit


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