{"id":292363,"date":"2023-07-10T17:43:06","date_gmt":"2023-07-10T17:43:06","guid":{"rendered":"\/forum\/forums\/topic\/residuals-oscilalting-using-the-species-transport-model\/"},"modified":"2023-07-10T17:43:06","modified_gmt":"2023-07-10T17:43:06","slug":"residuals-oscilalting-using-the-species-transport-model","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/residuals-oscilalting-using-the-species-transport-model\/","title":{"rendered":"Residuals oscilalting using the species transport model"},"content":{"rendered":"

Hello,<\/p>\n

I am running a Fluent simuation on a rectangular channel with 1 inlet 1 outlet<\/p>\n

<\/p>\n

I am using the species transport model, I have a mixture of methane + air, I left all the default values for the reaction (1 step reaction)<\/p>\n

<\/p>\n

I have the following for my inlet setup<\/p>\n

<\/p>\n

 <\/p>\n

<\/p>\n

And for the wall around it, I left the default values for the momentum and species tabs<\/p>\n

<\/p>\n

After 500 iterations, my residuals look like this<\/p>\n

<\/p>\n

Do the oscillating residuals necessarily mean that my solution is not converged or can it be an indication that my simulation is by nature not steady state? If the latter is the reason, what would be an appropriate way to evaluate convergence?<\/p>\n

My second question has to do with patching. Initially when I tried to run this, I was not getting any reaction (when looking at a contour of the species for instance, I was not observing much of a change).<\/p>\n

Looking online, I saw that people were suggesting patching a high temperature (2500K) at the initialization step. After that I observed signs of a reaction<\/p>\n

<\/p>\n

So is patching just attaching a temperature in the cells initially to start the reaction, or is this temperature sustained throughout the iterations as well? Is it possible that the patching step I added has something to do with my oscillating residuals?<\/p>\n

Thanks<\/p>\n","protected":false},"template":"","class_list":["post-292363","topic","type-topic","status-closed","hentry","topic-tag-fluent","topic-tag-species-transport"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t