[wididid]

Hello,

In simulating a supersonic bow shock on an air jet thrusting into the flow with rhoCentralFoam, I have produced some results that I do not believe are correct. The bow shock caused by the air jet is significantly further from the body than it should be. Because of this, I suspect that my boundary conditions are incorrect, specifically the supersonic freestream boundary conditions.

My intention is to have the freestream boundary condition be at the following conditions: Temperature or 173.4 K, velocity of Mach 2, and a total pressure of 13789 Pa. My current setup uses the fixedValue boundary with a pressure of 1762, which is my calculated static pressure. Switching to using the totalPressure boundary condition resulted in my simulation crashing very early on. My current setups for P, T, and U are below.

P:

...
dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 1762.3;

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 1762.3;
    }
...

T:

...
dimensions      [0 0 0 1 0 0 0];

internalField   uniform 173.4;

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 173.4;
    }
...

U:

...
dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (488 0 0);

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform (488 0 0);
    }
...

Could someone suggest to me why the totalPressure boundary condition did not work or help me write correct boundary conditions for this case?

Thank you

[wididid]

I suppose I should make my question more clear since it is a little vague. I am using RhoCentralFoam to simulate a rocket engine thrusting opposite of Mach 2 flow. I have this working but am creating a bow shock 40% greater than expected. However, I am using a fixed value boundary condition set to a calculated static pressure 1762Pa. I have set the static pressure higher (by 10X) and the bow shock gets much smaller, as expected. As such, I believe pressure to be the immediate issue.

I would like to use Total Pressure (since that is the known value given to me). However, if I use the Total Pressure boundary condition set to 13790Pa (the known value of total pressure for the freestream) and run the simulation with all other factors unchanged the simulation crashes due to a negative initial temperature within the first few time steps. I've isolated the problem to be occurring on the inlet patch for the freestream where paraView is showing a very sharp change in flow parameters between the total pressure boundary condition and the initial internalField pressure of 1792Pa. To me it seems that the internalField is not set to the correct pressure for the given total pressure even though I calculated it to be 1792Pa.

Questions:

1) Has anyone encountered a similar problem when specifying Total Pressure? If so, what was the cause and remedy?
2) When applying a fixedValue boundary condition, is it specifying static, dynamic, or total pressure?
3) Are there reasons that rhoCentralFoam would be failing to correctly predict where a bow shock in this situation would form?
4) Is there a more accurate solver for this situation than rhoCentralFoam?

I have attached an image of my case.

Thank you