How to increase accuarcy when node limit is reached

General discussions about how to formulate a script for FlexPDE.

How to increase accuarcy when node limit is reached

Postby Myopic on Tue Jun 05, 2018 11:44 am

Hi I am running a thermal simulation and I keep hitting the 2million node limit but I desire more accuracy because my contours plots still look very jagged and not smooth as I need.
The simulation geometry is very simple and is essentially a box and within the box there is a cylindrical region where heat generation occurs.
I have already scaled the z direction so this isn't an issue. The program also runs very quickly(10 minutes) so I dont see why I cant increase the number of nodes and let it run longer because some other simulations I've seen can take 2 hours, get better accuracy, have fewer nodes, and have more complicated geometries. So idk what the problem is or what I can do to rectify it.
I am running flexpde5 and have attached my file.

Thanks!
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GaO_1.pde
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Re: How to increase accuarcy when node limit is reached

Postby moderator on Wed Jun 06, 2018 1:31 pm

Two million is already an insanely large number of nodes. The mesh size limit is not the problem.
Something else in your problem definition is unstable.
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Re: How to increase accuarcy when node limit is reached

Postby moderator on Thu Jun 07, 2018 2:37 pm

Explain to me which plots remain jagged.
They look reasonable to me, except the top surface plot, which has a total range of only one percent of the overall temperature variation.

You would be better off manually increasing the mesh density in the cylinder, rather than letting the mesh refiner do it. (The mesh refiner wants to resolve the steep gradient at the edge of the cylinder, not the low-lying values on the top surface.)
You can put a Mesh_Spacing=100 control in the full cylinder or just in the heated layer, whichever suits your needs better.
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