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tutorial sample ft08_navier_stokes_cylinder

+1 vote

This test case runs slower and slower as time goes. It take 1 second to finish the first 30% time-stepping but takes more than 5 seconds to run a single step in the last 20% of time stepping. I read the file and thought that the computational complexity shall not increase over time. Anyone have the similar observation? Thanks! - yc

asked May 23, 2017 by yzhou FEniCS Novice (150 points)

1 Answer

+2 votes

Yes, I see the same slowdown when running that script. It seems to be caused by the call to plot in line 139:

plot(u_, title='Velocity')

When I remove this line, the script runs with the same speed for all time steps.

answered May 24, 2017 by johannr FEniCS Expert (17,350 points)

This is it - thanks!

commented May 24, 2017 by yzhou FEniCS Novice (150 points)

I waited over 24 to have the simulation get to only 54%. Commented out the plot and it finished in just a couple minutes! Thanks!

commented Jun 10, 2017 by drhandwerk FEniCS Novice (140 points)

This seems to only be a problem with the Matplotlib backend, not the VTK backend.

commented Jun 12, 2017 by johannr FEniCS Expert (17,350 points)
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