Comments

Total pressure and temperature in this case is calculated on the assumption that the expansion of the gas flow reaches 7.5 Mach velocity and static pressure and temperature will match your predetermined altitude. Typically in CFD codes this calculation is done automatically using the formula for adiabatic expansion of gas

e.g. in OpenHyperFLOW2D for your case

Mach=7.5 U=2737.31 m/sec T=216.7 K p=5529 Pa p*=2.78713e+07 Pa T*=2863.29 K

Well, first of all it is necessary to agree on the terms.
I do not know which solver you use. So let's start with their classification.

At first:

Solvers are dimensional and dimensionless. Most solvers dimensionless. In contrast OpenHyperFLOW2D - originally the dimensional solver as its core code was created for the engineering design. That is, all the differential equation in this case are written in dimensional form.

Secondly:

Solvers are use the concept of a gauge pressure (p_g) and using the absolute pressure directly. In case of gauge pressure concept, to obtain the absolute pressure we should add gauge pressure to the pressure, which operates solver.


OpenHyperFLOW2D initially uses the concept of absolute pressure directly

Next point, the physical aspect of your case.
When you say "Oulet pressure BC - 0 P" it means outflow in the vacuum ?

In my case outflow occurs in the atmosphere,
that is equal to the ambient pressure 1.0e5 Pa

If your solver uses the concept of a gauge pressure then your BC can mean both.

It depends on the value of gauge pressure:

p_g = 0 Pa -> vacuum outflow
p_g = 1.e 5 Pa -> atmosphere outflow


In the case of outflow in vacuum instability is normal. In this case, usually zero pressure replace a very small non-zero,
but not everyone solver can be considered this (OpenHyperFLOW2D can)

Now concerning the the initial and BC of the above case:

Since the problem of axially symmetric, simulated only half the nozzle.
Image obtained with a full nozzle in the postprocessor.

BC:
- X- axi - symmetry BC (radial velocity and gradients of all parameters is zero)
- left boundary in chamber - Dirichlet BC with total pressure 7.2e6 Pa and total temperature 3338.5 K.
concentration of combustion products - 100%, air - 0%
- left boundary in ambient area - Dirichlet BC with total pressure 1.0e5 Pa and total temperature 300 K.
concentration of combustion products - 0%, air - 100%
- top boundary - Dirichlet BC with total pressure 1.0e5 Pa and total temperature 300 K.
concentration of combustion products - 0%, air - 100%
- right boundary - Neumann BC with zero gradient in axial direction
- nozzle walls - "no-slip" BC

Initial conditions:

- chamber from left boundary to throat filled gas with total pressure 7.2e6 Pa and total temperature 3338.5 K.
concentration of combustion products - 100%, air - 0%
- another domain part is filled gas with total pressure 1.0e5 Pa and total temperature 300 K.
concentration of combustion products - 0%, air - 100%

The boundary between the domains simulates a frangible disc in throat of nozzle.

So as not to attract attention spambots I do not give here my e-mail, but you can easily find it in any files header of OpenHyperFLOW2D project

I do not quite understand your question. What do you mean by this case, "similar work"? The models, which are used in my code are briefly described in the wiki. Or you mean a picture with a Nozzle case that is show as an illustration?

This is due to the fact that the one cluster was used Infiniband DDR and has nodes on NUMA architecture and a smaller cache (Opteron 285) against the other cluster which used SDR on the SMP (Xeon) and large cache.

The addition for each node we has two data exchanges (except first and last node) on Infiniband and 3 exchanges of internal memory (SMP or NUMA).

PS: If I use one process per node (exchange only for InfiniBand) that scalability will be even better, it's a paradox but a fact