Hi, can anyone please tell me the main role or function of the under relaxation factors.Is there any connection between the under relaxation factors and the convergence criteria which is set in the monitor residuals dialog box? i am tryng to model the melt pool geometry in FLUENT but it is constantly giving divergence. regards, Fareed

Under relaxation factors is to avoid the numerical diffusion, speed up the convergence, and to control and to avoid the divergence of residuals. Under relaxation factor is basically a residual controlling machine. Check your time step value also if you are running a transient simulation. Also, check the type of discretization scheme you are using because that could be a factor as well.