[Romanticjune]

My model is a porous zone with the size of 3cm*1.5cm*1cm, where combustion(CO/H2/CH4) takes place. The combustible gases are generated from the "source term"in porous zone. Oxygen is injected by the channel which is through the porous zone and the raw gases are pumped out.

The interface between the 'porous zone' and 'channel' is set to 'interior'.
In the beginning, a 'heat source' in fixed to 1500℃ to heat the porous zone. When the O2 out from the channel run down, the heat source is off and the energy from the combustion to sustain the reactions in the porous zone which is producing combustible gases(source terms).
Problem just occurs after the heat source is turned off, the species/output temperatures/output massflowrate changed regularly up and down.After some check, I found it was caused by the reactions of 2CO+O2=2CO2. When I close the mechanism of the reaction, the plot goes well.



Is there any methods of alleviating this"vibration"? Thank you very much!