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#1 |
New Member
Join Date: Nov 2016
Posts: 10
Rep Power: 9 ![]() |
Hi,
I have what may be a very mundane question. I'm trying to solve a system of equations to very tight tolerance. For my numerical experiments, I've been using the laplacianFoam solver and running to steady-state. I am using a linear domain (one row of cells) with BC x = 0 , T = 1 x = 10, T = 0 I then run the solver with fvSolution dictionaries: solvers { T { solver PCG; preconditioner DIC; tolerance 1e-20; relTol 0; } } I want to see my initial residual fall below 1e-20, but this appears not to be possible. No matter how many cells I use or what tolerance I specify, the smallest absolute residual I see is ~1e-16. The final residual will go as low as I specify in tolerance, but always I see the initial residual jump back up to about 1e-16. My question is this: Why can't I solve to a tighter tolerance? How do I accomplish this? Thanks! |
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Tags |
accuracy, residuals, tolerance |
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