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July 25, 2013, 05:24 |
SSIIM2: constant continuity residual
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New Member
Miss Mummputz
Join Date: Sep 2012
Posts: 7
Rep Power: 14 |
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 |
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