[Athos_e]

Hello everyone,

I've been trying to simulate a shock tube detonation using SU2 NEMO and MUTATION++. I will outline the procedure first:

My shock tube is composed of two zones, the left one that is a short zone with high pressure and temperature in order to initialise the detonation, and the right zone that has gas in ambient conditions. Following another thread I was advised not to use multizone simulation as this is not very efficient. So what I did was to create two different meshes and 2 different cfg files for the two sections I described above. Having ran each sim for 2 iterations (since I use 2nd order dual time stepping, two iterations are required to have a restart solution) I obtained two restart files that I later on combined into one using a script. This restart file basically includes the points of the whole domain, both the left and right section. I validated that this procedure works as I ran the same case with Euler as a solver and I obtained similar results to mutizone approach and Euler. Therefore I can confirm this apprach works.

However the problem arises when I use nemo_navier_stokes as solver. In particular when I wan to include chemical kinetics and so set FROZEN_MIXTURE to NO in the cfg file. I noticed that by using nemo_navier_stokes with mutayion++ but setting FROZEN_MIXTURE to YES i.e no chemical kinetics, the expansion of the gas is as it should. Since my shock tube has 3 walls and an outlet, the high pressure packed on the left side of the tube will naturaly epand towards the outlet, which is what happens when ignoring the chemical reactions.

However, as soon as I include chemical reactions with frozen_mixture= NO, the simulation gives wrong results. Instead of having a wave moving towards the right, all the parameters (pressure, temperature, mass fractions etc) change along the whole domain at the same time gradually. Please see the attached pictures to give you a better undertstanding.

Has anyone experienced anything similar, and does anyone know why this might be the case? Is this mutationpp related or?

Thanks in advance and best regards,
Athos