I am currently doing research in a CFD project which is a unsteady study. Although all the residuals of k-w turbulence model are converging, the continuity one is converged to 1e-002 level while others are converged to 1e-005 level. The solution is exceeding 10000 iterations.
The convergence criteria are the same as that for steady-state simulations. A right way to stop the simulations would also be to see whether the respective 'fields'' have achieved steady-state by plotting their variation with respect to time. After that, you need to refer to time-averaged fields for understanding the physics.
Convergence using Residual Values. The residual is one of the most fundamental measures of an iterative solution's convergence, as it directly quantifies the error in the solution of the system of equations. In a CFD analysis, the residual measures the local imbalance of a conserved variable in each control volume.The most relevant factor is the time step in transient case and under relaxation factor.However, the predicted results should be compared with another numerical data and experimental results.
Dear Shamudra Dey
Following link may be helpful for you.
https://www.engineering.com/DesignSoftware/DesignSoftwareArticles/ArticleID/9296/3-Criteria-for-Assessing-CFD-Convergence.aspx
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