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Old   May 27, 2016, 16:25
Default Cut off Streamlines
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I am trying to make a simple simulation of the GE90 engine. I have two flow paths, the bypass and core flow shown in the picture. I can't seem to figure out why the lines are being cut off when looking at the results in the post-processing pictures.

The way I have set it up, I have mass flow leaving the enclosure and entering the bypass and core channels. I have double checked that the numbers add up and make sense.

As you can see in the pictures, some streamlines do make it through, but not all of them, so what could be the cause of this?
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Old   May 28, 2016, 06:07
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Have you tried the "Cross Periodics" option?

Also have a look at the streamline termination controls. Something there might be causing it.
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Old   May 28, 2016, 08:22
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Yes I have "Cross Periodics" enabled for all streamlines. Where might I find the streamline termination controls (still learning )?

I literally just restarted Ansys and opened up the project and now the Bypass stream looks good where as the core streamlines are still cut off. This is so bizarre haha. Also, would you happen to know what those grey lines are that are going diagonally backwards?
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Old   May 28, 2016, 08:36
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Interestingly enough, I can plot the streamlines of the core after it exits the engine, just not inside the engine which is pretty weird
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Old   May 29, 2016, 07:44
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Try playing with different seed points. Try using the whole domain as a seed point.

Also try forwards, backwards and both for integration.
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Old   May 29, 2016, 09:32
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haha yup already tried that
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Old   May 29, 2016, 19:44
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When streamlines go through tight passages, sometimes they hit the walls due to inaccurate integration. Also look at the integration accuracy parameters.
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Old   May 30, 2016, 17:18
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I redid it all with a finer mesh, that fixed this problem haha. Thanks for the help!
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Old   May 30, 2016, 21:14
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The problem was likely to be integration accuracy then. On a coarse mesh the streamlines hit the wall and are terminated. Streamlines are mapped more accurately on finer meshes and so stay inside the fluid domain.
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Old   May 30, 2016, 21:16
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Right, that makes sense! I will be sure to remember!
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