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andreasp October 22, 2012 04:47

Dear CFD community,

we are using a stabilized first order Finite Element code for simulation of incompressible flows. At its core, the code utilizes a (usually non-preconditioned) GMRES method for solving linear systems.

In general, it is quite difficult to find an "ideal" setup of the GMRES algorithm for a given problem, i.e. especially to find a suitable size of the maximum Krylov space dimension (inner iterations). I wonder if there are any estimates for determining such parameters beforehand, in order to circumvent some of the trial and error procedure (which is really cumbersome and painful for large problems). Maybe someone can point me to literature where such an issue might be discussed....?

Thanks for any help!

cdegroot October 23, 2012 15:43

Nice post. I've looked into this in the past, but also found no suitable answer. I'd be interested to know what others have to say. I actually found for the linear systems I was using GMRES wasn't a great choice and found better convergence using a TFQMR solver. I'm sure that is not a general result though, just a property of the linear systems I was constructing.

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