I need to preform 100s of linear thermal simulations on a single mesh where all I do between different steps is change the boundary temperatures. I was wondering if there is a way to use one of the direct solvers to factor the matrix once and then use the factored matrix for all of the simulations, instead of refactored the matrix for every simulation.
The CalculiX functionality closest to what you want to achieve is restart capability. It allows you to run the first step of the analysis once and then run more steps with different settings without having to recalculate that first step. So you could even solve an empty step (e.g. with initial temperature only) and then follow it with multiple versions of the second step. All of them would continue from the first one, with conductivity matrix already calculated.
I see, thanks for the info. I did not see a change when moving the RESTART after HEAT TRANSFER.
I’ll mess around with it more today with different structures. It’s also possible I could do something like Disla suggested with large time steps to converge to steady-state quickly (I’ve never done transient in Calculix though so I’m not sure).
Thank you both for the advice! I’ll reply back here if I make more progress.
According to the manual section 7.104 “restart, read” should be the very first non-comment line in the data set.
I have never tested it on a thermal calculation but static linear/nonlinear it works this way.