Learning Forum

[Simão Martins]

Hello, I'm trying to set up a simple 2D axisymmetric simulation using the compressible CESE Chemistry (inviscid). I defined an H2-O2 reaction mechanism with 8 reactions and gave the thermodynamic input file.

Background:
The simulation domain is a rectangle with solid walls and an ignition zone with high pressure and temperature. When I use a 2D planar simulation (igeom=2), a shock wave develops and propagates in the H2-O2 mixture. The temperature, pressure and speed of the shock wave closely match the theoretical CJ values for hydrogen detonation, so I assume the simulation is correct (see the image below). 

Problem: 
However, when I switch to the 2D Axissymetric simulation the simulation doesn't converge and weird/non-physical values show up in the results. Instead of a uniform propagation of the shock wave, I get random spots with non-sense values (even away from the ignition point), as shown below. The only difference to the 2D planar simulation is that I define the *CESE_BOUNDARY_AXISYMMETRIC in the y-axis and change the *CESE_CONTROL_SOLVER card to perform a 2D axisymetric simulation (igeom=101). 

The error message is:
 *** Error 150209 (CHEM+209)
     Chemistry EOS nonlinear temperature solver failed to converge.
     Error code = 50 Last iterate temperature = -0.21165E+04

I tried to simplify the problem by reducing the reaction mechanism and removing the ignition but the problem persists. Additionally, I reduced the mesh size and the time step and still doesn't converge. However, if I run the CESE axisymmetric simulation without the chemistry cards the results are okay.

Has anyone faced similar problems or has any idea on how to approach these issues?? 
I need to set up the axisymmetric case since my next step is to run a simulation of a cylinder with bigger dimensions. 

[Ushnish Basu]

We have fixed several bugs recently regarding the chemically-reacting flow solver, especially as affecting the 2D-axisymmetric case.

Please try out a recent Dev version or an updated R15 version. You will have to contact your Ansys account representative to get access to these version.