Post
by Christian Bludau » Wed Sep 07, 2011 7:31 pm -1100
Hello Joseph,
first I have to say, yes, Wufi 2D needs its time. But if you use a not to huge construction and an appropriate grid, it can speed up things. Unfortunately thats not the only influence to the speed. Also the composite of the construction, the initial conditions... have an influence. But to your questions:
1)2) It is possible to use bigger time steps. For that go to the "Enhanced"menu in Computational Parameters. Here you can change the time step. 2 hous would be 7200s. But keep in mind that this will have an effect on the accuracy of the results, mainly the relative humidity.
3) No, there is no influence of the orientation of the boundary conditions. It more could be the boundary condition itself. For example if you have a high number of days with precipitation, it slows down the calculation, because you need more iteration steps (rain iteration) for every time step.
4) I do that really seldom, only in case of special question.
5) Yes. Try to brake down your construction to a as simple and as small as possible model. Cut the constructions at symmetric axes. Do not simulate a 10meter roof section, only because it is 10meters long. Cut in the middle of the mineral wool on one side and in the middle of the rafter on the other side for example.
Further the grid is important. Do not make it too fine, it will take much time but also do not generate it too small, the results will be not good. A steady-going grid will show better convergence behavior, than a size-jumping-grid. The expansion factor should not be higher than two respectively lower than 0.5.
There is also a influence of the used materials in the construction. If there is a heavy bend in the moisture storage, convergence may be much harder than with a steady-increasing function (maybe generate it).
But for short: The best way for a faster simulation is to keep the construction as simple as possible and the grid as small as acceptable. I would not screw around with the time. Better set up your construction during day and let it calculate during night.
If you use an notebook, keep in mind that some settings may slow down the processor during you are not working (only calculating) with it to save energy.
Hope that helps,
Christian
