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-   -   motorBike Tutorial: Cannot plot U and solution seems not to converge (http://www.cfd-online.com/Forums/openfoam-solving/110352-motorbike-tutorial-cannot-plot-u-solution-seems-not-converge.html)

Jaggy_Snake December 9, 2012 09:58

motorBike Tutorial: Cannot plot U and solution seems not to converge
 
Hi again,

I have ran the motorBike tutorial and can view pressure contours on the geometry surface (I have posted a screenshot below as I'm unsure how accurate the pressure data is), but when I try to plot the velocities, the entire surface is a big red 0m/s!

What is strange is that when I go into my U files of my 5 timestep directories I see quite plausible velocities - around 20 m/s in the x-direction and close to zero in other directions - yet this won't show on ParaView.

This is similar to the situations reported here and here (circa 2009) but the issue in those cases was because of a bug in OFv1.6. I'm running 2.1.1.

Also, I can't plot residuals and instead I get the following, suggesting the solution has not converged:
Code:

SIMPLE: no convergence criteria found. Calculations will run fo 500 steps.

Starting time loop

End

If it's not converging, wouldn't my velocities and pressures be noticeably erroneous.


Can anyone offer any advice?

Thanks, Fergus


http://i200.photobucket.com/albums/a...2-09213926.png

Doug68 December 10, 2012 02:01

The reason you can plot velocity on the surface is because the surface is not moving. The air next to the surface is the stuff that's moving, if you create a slice or some such through the model than you should be able to visualize U on that.

you will need to open the model twice in the same session if you wish to see the surface of the motorbike and slices, streamers or whatever else you create at the same time.

On the convergence issue. If you look in fvSolution I expect its not been set to stop the run when convergence criteria are met, but instead run for 500 iterations and then stop. If you run the foamlog function on your simpleFoam log file then it will extract the various residuals and put them each in there own file.

Jaggy_Snake December 11, 2012 07:27

Ah great. I should start thinking about things rather than panicking and coming straight here... :rolleyes:

Thanks Doug


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