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zv08 March 11, 2013 08:01

Question about behaviour of the continuity converge accelerator observed
 
Hi,

I need help understanding why the following is happening.

I have a simulation of an aerofoil with a piccolo tube (for leading edge heating) in a free flow. I need to compare the results with and without the continuity convergence accelerator activated for coupled implicit solver.

The simulation runs fine without and gives expected results. Then, when I turn the CCA on the solution diverges, no matter what under-relaxation parameters I put in or if I ramp it for the CCA.
However if I initiate the problem and run it for 1 iteration without CCA then turn on CCA it solves. (If I initialise without then run with without having first run for even just 1 iteration it gives me a floating point error also).

I wondered if anyone could explain why this might be.

Thank you.


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