Asking the usage of First Law of Thermodynamics in CFD..
 

Dear all,
I have read "Computational Fluid Dynamics" written by T.J. Chung. On the book page 35, i read that for Incompressible flow, navier stoke equation is derived from First Law of Thermodynamics (FLT). But, for compressible flow (discontinue flow) the navier stoke derived from Conservative form Navier Stoke (CNS) and Control Volume Surface (CVS).
Can you explain that?? Because I'm still confused of usage of FLT. I think FLT will be used on heat transfer case only.
Thank you
Teguh