[deepbandivadekar]

Hello all,


Probably a very simple answer to this but can't seem to get my head around it.

What do these kind of boundary condition really mean:

boundaryField 
22  { 
23      inlet 
24      { 
25          type            fixedValue; 
26          value           uniform 1; 
27      } 
28   
29      outlet 
30      { 
31          type            waveTransmissive; 
32          field           p; 
33          psi             thermo:psi; 
34          gamma           1.4; 
35          fieldInf        1; 
36          lInf            3; 
37          value           uniform 1; 
38      } 
39

e.g. as we can see here in section 5.2.2 of: https://cfd.direct/openfoam/user-guide/v6-boundaries/


Is it a normalised value (pressure/temperature/...) ? If so exactly how?
I do not understand how Mach number is calculated as 3 at the inlet when the temperature is initialised as 1 for the forwardStep tutorial of both sonicFoam and rhoCentralFoam (the velocity is is 3 in both cases: that means sonic speed is taken as 1. How?).



Can someone please explain the background or please direct me to right resources? I tried to look up threads, couldn't find anything.

[deepbandivadekar]

I found my answer here: https://www.openfoam.com/documentati...p#x11-560003.2


What I had assumed was that the fluid is air thus the confusion. This short description cleared it well.