[A CFD free user]

Hi friend,
Obtaining a value of e-2 or even e-4 for residuals doesn't necessarily mean that your simulation is converged. However, a value of e-3 is acceptable for continuity, for other equations, it depends on your problem. For instance, in my recently work, a value of residual about e-8 is not enough to get convergence for a user_defined scalar! So, my suggestion is first, keep doing iteration until you don't observe any big change or oscillation in residuals. Secondly, in some cases, you need to monitor some effective parameters in your model beside the usual residuals monitoring. For example, depending on your work, you can monitor some surface or volume characteristics of flow. Only one more thing, in some cases you may not receive a very low residuals but the values will not change any more longer. In that case, your simulation is converged too. So, don't worry and be patient when you grip into a CFD problem.
Hope it helps.