Hello While simulating two phase flow. I find that for some cases especially for high particle loading. The convergence criterion (residual source)has to be set at 0.1 other wise convergence was not taking place. (tried all other things - grid size, under relaxation etc..) Is it o.k. or justifiable (do i have life after this?) thankyou for the suggestions

Once in my calculation, I find it very difficult to converge to the 0.001 set by FLUENT. Later I emailed their person, they said in some case 0.01 is good enough. The idea is that you need to look at some key variables of your calculation. If it does not change too much when convergence criteria change, you can be at ease with the 0.01. But, as you say, it is hard for you to get 0.001 convergence, so this may not be too helpful. But, I think if your variable seems in a correct direction, and you can trust the result in a sense.

Probably you also need to pay attention to your

1. Discretization scheme,

2. Aspect ratio of grid (for FLUENT, >5 sometimes pose difficult to good calculation)

3. Physical model (say two phase flow model and other stuff)

and so on.

Hope to be helpful.