topic Re: XY plot showing zero values in CFD Forum

XY plot showing zero values

Anonymous — Thu, 10 Sep 2020 14:10:52 GMT

Hi,

I'm trying to plot velocity data across a square channel - I get a general trend of plug flow (using a shear thinning fluid), but there are some values reading zero velocity (see 0.07 - 0.08 cm on X-axis in screenshot). This is occurring even though the histogram of the plane shows good laminar velocity behaviour. Does anyone know why this is happening and of any solutions to it?

Thanks,

Cate

Re: XY plot showing zero values

frederic.gaillard.7 — Thu, 10 Sep 2020 14:46:16 GMT

Hello Cate,

Try to increase the number of point. 100 instead of 20.

Fred

Re: XY plot showing zero values

Anonymous — Thu, 10 Sep 2020 14:56:05 GMT

Hi Fred,

I'm still getting the same issue (see attached!). Although some data has come back...

Any other suggestions?

Cate

Re: XY plot showing zero values

frederic.gaillard.7 — Thu, 10 Sep 2020 15:05:32 GMT

And if you rotate your XY plot of 90deg ? do you have the same result ?

Re: XY plot showing zero values

Anonymous — Thu, 10 Sep 2020 15:12:22 GMT

Yes - I still have zero values in the velocity profile

Re: XY plot showing zero values

frederic.gaillard.7 — Thu, 10 Sep 2020 15:32:09 GMT

Hello Cate,

It's really strange because the velocity field picture doesn't add up with the XY plot.

Close, relauch the software and draw another XYplot.

Fred

Re: XY plot showing zero values

bob.schlosser — Thu, 10 Sep 2020 15:37:23 GMT

If you save the data out from cfd do the individual points have data? I'm curious if this is a bug in the graph or if it is not actually capturing data prior to graphing.

Re: XY plot showing zero values

CGBenner — Tue, 15 Sep 2020 15:24:38 GMT

@Anonymous Did the information provided answer your question? If so, would you please use Accept Solution so that others may find this in the future? Thank you very much!

Re: XY plot showing zero values

Anonymous — Wed, 16 Sep 2020 08:12:56 GMT

If I save the data as a .csv file, I still get zero values in the data! Closing the software and reopening doesn't solve the issue

Re: XY plot showing zero values

frederic.gaillard.7 — Wed, 16 Sep 2020 14:07:13 GMT

Hello @Anonymous ,

Can you share your cfz file ?

Thx

Fred

Re: XY plot showing zero values

Anonymous — Mon, 21 Sep 2020 13:39:29 GMT

I've attached a .csv file

Re: XY plot showing zero values

bob.schlosser — Mon, 21 Sep 2020 13:43:20 GMT

Unfortunately a csv file will not be of much help. It will only show that their are zero's in your data similar to what you have previously stated. Could you zip and attach a cfz share file from CFD? This will allow others to explore the simulation and see if we can help.

Re: XY plot showing zero values

Anonymous — Mon, 21 Sep 2020 13:51:55 GMT

Ah ok - here is a .cfz file

Re: XY plot showing zero values

bob.schlosser — Mon, 21 Sep 2020 14:53:21 GMT

Hello, I changed the boundary conditions to only have one surface with a flow rate. The other surface was changed to P=0.

I was then able to graph across the flow without missing any points. Putting a flow rate on the in and out effectively over constrains the system since FEA needs the freedom to have a very small rounding error to converge.

A side note, I would also increase your wall layers and use a finer mesh on your model.

Re: XY plot showing zero values

Anonymous — Tue, 22 Sep 2020 10:07:46 GMT

Great, that's helped me!

Thanks 🙂