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-   -   momentum & x-vel convergence, and reverse flow problem (http://www.cfd-online.com/Forums/fluent/116319-momentum-x-vel-convergence-reverse-flow-problem.html)

cinwendy April 17, 2013 02:19

momentum & x-vel convergence, and reverse flow problem
 
Hi,

I have been using FLUENT for a while, trying out my own calculations and looking at past posts here. I still have some questions:

1, I have know that even if continuity residue does not really converge (say, to 1e-6), I can use mass flow rate to check that mass is conserved by getting a small number (say 0.5% of inlet mass flow). What about x-velocity residue convergence problem?

2, Some of my calculations has "reverse flow in <how many> faces in pressure outlet" during the iterations. They are intermittent, I can get 50+ iterations with reverse flow then 100 normal lines, then reverse flow appear again. My calculation is steady atate, which I want to use it as the initial condition for transient state. Is this normal? Or I should do something?

3, If I am running a transient simulation. as long as the residue are falling down, or falling until a pleateau, but doesn't reach 1e-6, is that ok?

My questions may be too "beginner" to you all. I really hope to get some expert advice. Thanks a lot!


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