SSIIM2: constant continuity residual
 

Hi!
I have more or less the same problem as student2008 in the thread

http://www.cfd-online.com/Forums/flu...ous-media.html

and can't solve it: I am simulating a straight river over a chute with SSIIM2. While all residuals become very small after some time, the continuity residual first oscillates and than stabilizes at a constant value (namely 52.2).
The sum of all the water inflow and outflow in the geometry is very low.

first I tried to lower the relaxation factors, however, this did not help anything.

in student 2008's thread people are talking about local scaling, so I scaled the residual taking the largest absolute value in the first five iterations as denominator (following the instructions described on

http://jullio.pe.kr/fluent6.1/help/h...def-resid-eq3a

)- however, the maximum value in the first five iterations is not very high and my scaled residual reaches a value of 0.5 which is not very good neither....
furthermore: why taking the largest number in the first five iterations? is this just some random presumption??

as my understanding of cfd does not reach very far, I would be pleased if you could tell me a possible reason why my residual stabilizes (???)

attached I send you a graph of my residuals

thank you so much!
Mummputz