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How can i get a smoother velocity profile plot?

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Old   July 15, 2018, 18:28
Default How can i get a smoother velocity profile plot?
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Hello,

i have the following problem, that i cant get a smooth and good looking velocity plot. In the plot are many sharp edge (see max. velocity).
I created a line through my geometrie and tried to get the values with "slice" and "1000 samples" but there was not difference. It seems the programm is using the cell values and interpolates it linear to the next cell value, so the plot ist put together out of many small straight lines. But i want it to be interpolated smoother.

Also if i export the csv file with the 1000 values along the line to matlab and try to plot it there, it looks the same. I hope you understand my problem and can help me to fix it

1.jpg
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Old   July 15, 2018, 20:16
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Glenn Horrocks
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You need to run the simulation again with a finer mesh. In fact, if your results have sharp edges like that it shows that you do not have a fine enough mesh anyway, so your results are likely to have a large error.
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Old   July 15, 2018, 21:04
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Quote:
Originally Posted by ghorrocks View Post
You need to run the simulation again with a finer mesh. In fact, if your results have sharp edges like that it shows that you do not have a fine enough mesh anyway, so your results are likely to have a large error.
I thought the same. But i am looking for a way to get better interpolated values without changing the meshsize.
I cant reduce the cell sizes that much, because then there will occur stability issues.
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Old   July 15, 2018, 21:36
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You will have to write a higher order interpolation routine yourself. There is nothing built into CFX to do this for you.

Instability is no excuse to stay with coarse meshes. I repeat - with a result that blocky it is highly likely your results are under-resolved and therefore grossly inaccurate. You will need to refine the mesh and handle the instability somehow (better mesh quality, smaller time steps, better initial condition, double precision numerics, transient simulation are all approaches to consider)
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Old   July 17, 2018, 16:22
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Even with a much finer mesh, the plot is still edged. At least i found out how to smooth my plots with matlab
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