Question to Residuals
 

Hey Guys,
I just finished my first real simulation with an amount of 6541099 cells and 500 iterations. To judge how good my simulation is, I wanted to have a look at the residual plot. And after seeing this my question is, why is there so much ups and downs. My lowest residual was 0.006, which is quiet high i belive.

https://gyazo.com/79ea9332f4ae41a43f3278413a003512


So i switched the normalization option from "Auto" to "Off", as told in another thread. Now I have much better residuals, as shown here:

https://gyazo.com/944f64e450d9efb5ba88713a187dd4fe

So my question is, what exactly does this normalization option do? And is my simulation "good"? :D


Thanks in advance :)

Look at the graphs again and squint a bit ;)
They are exactly the same, just with an offset to each line. So none of them is better than the other. The CCM+ manual explains quite well how residuals are normalized. IIRC they use the maximum value over the first 5 iterations for normalization.

If you want to judge how good your simulation result is in terms of iteration error, at the very least you should be monitoring the quantities you are interested in. Looking exclusively at residuals will mislead you.
There should be a lengthy thread about this topic buried somewhere in the forum: https://www.cfd-online.com/Forums/fl...nvergence.html