I've posted a few threads about this topic. For now, I can model methane combustion with surface mechanism only successfully. I am trying to include both gas phase and surface mechanism. I followed exactly the same setting in literature except I did not include radiation since divergence problem. The residuals show that the case is converging as shown below:
The temperature of the out wall is set as constant 773 K. In order to ignite the mixture, I tried two methods. One is by setting a high enough temperature to the catalytic wall firstly and calculate for hundreds of iterations. Then reset the thermal boundary condition to coupled. The other method is to patch a high temperature to the whole computation domain. My problem is no matter what I do, maximum temperature in the domain keeps decreasing until to the out wall temperature 773 K. Namely, all reactions do not happen. I put the temperature contour as below. The maximum temperature should be 1800 K according to literature.
another aspect that confuses me is the contour of methane model fraction. I set the mole fraction of methane of inlet to 0.105. However, the contour shows that the mole fraction of methane near inlet is 0.0864 which is smaller than the value 0.105. This does not make any sense.
Can anybody help me to check my model?