effect of under relaxation factor on the fuel flow
 

Hello everyone, I am working on the mixing of the gasious fuels in the pre mixer using Ansys fluent. When I use the species transport method, there's no problem with the residual, but when I use the non-premixed cobustion method under same conditions, the residual start making oscillation. Therefore, I changed the under relaxation factors, so, the solution is converged, but the solution contour showed the changes in the fluid flow. So, kindly is there any one can help me to solve this problem? Thanks.