I'm currently doing two simulations. One of the Residual diverges in the beginning for around 100 iterations. Though it converges eventually till 0.001. Is it fine and acceptable? Another one diverges abit in the beginning and have zick zacks when the residual stays 0.001. I've checked the Cell Quality, whether I#m using the right Condition, checked the Wall Y+ and it's all fine. Are both the Simulations not acceptable? Are those Simulations, which Residuals have zick zacks of diverge few times but eventually converge acceptable?

Is it alright for the residual diverges few times before it converges to 0.01?

Ping,

For the fluctuation part, you should notice the level of deviation of you residual. There may be local fluctuations, but if the overall trend is decreasing then you can rely on it. These fluctuations give an indication of how stable your simulation has become. And these fluctuations come mostly due to some local-domain parameters' imbalancing. If your area of intereset is to focus on global values, then its better that you rely on these values.

Most practical method is to look into your result and check for unrealistic values of solving parameters in your calculation domain, if it is there.

Regards,