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-   -   Error in CFX run (https://www.cfd-online.com/Forums/cfx/214943-error-cfx-run.html)

tyw7 February 18, 2019 14:30

Error in CFX run
 
2 Attachment(s)
I am trying to simulate a flying wing in CFX and I got this cryptic error:
ERROR #004100018

I have tried increasing the time step but it still bawks at me after round 2.

See attachment for log.

Edit: Fixed problem by editing mesh. Previous mesh had error messages.

Edit: Run 2 failed.

ghorrocks February 18, 2019 18:35

FAQ: https://www.cfd-online.com/Wiki/Ansy...do_about_it.3F

tyw7 February 18, 2019 18:37

I had a look at that but I am hitting a wall. No idea where the error is coming from.

I changed time step, smaller mesh, etc. I can't really move the outlet since I am hitting the solidworks limit.

ghorrocks February 18, 2019 18:42

Solidworks limit? What is that?

Please attach an image of what you are modelling. If you have progressed beyond the output files you have already attached then attach a current output file as well.

tyw7 February 18, 2019 18:46

https://transfernow.net/ddl/flyingwing1

Here's the model

How to upload the mesh?

https://forum.solidworks.com/thread/22416

ghorrocks February 18, 2019 19:06

I don't download from strange sites. Just post some images on the forum. Don't bother uploading the mesh, I won't look at that either. Just post images on the forum.

You have only said you are modelling a wing. How big is it? How fast? What fluid is it moving in? 2D or 3D? Any appendages? What results do you want to get (lift, drag, moments etc)? Why are you doing this analysis?

tyw7 February 18, 2019 19:19

2 Attachment(s)
Well the wing is 62.6 m long as it's a flying wing. Doing analysis as part of year 3 project

Moving at Mach 0.85.

ghorrocks February 18, 2019 22:50

You still have not explained much about what you are doing. I cannot give much of an opinion if you do not explain what you are doing.

However, I can see that your mesh is very coarse. It also does not have inflation/prism layers. While it is OK to do debugging on very coarse meshes it will give very inaccurate answers and occasionally strange error messages (such as what you are seeing).

Once you have the basic simulation working correctly you will need to do a mesh sensitivity study to determine the mesh resolution you require for accurate results. I can assure you it will be far finer than you currently have. You will also need to do a convergence criteria and boundary proximity sensitivity study as well.

tyw7 February 19, 2019 04:23

That's the problem. I cannot go finer or I'm hitting the 512k limit. Also, I have an inflation layer of 50 layers, first level thickness around 0.004 m

ghorrocks February 19, 2019 04:37

Do a careful sensitivity analysis to determine exactly what mesh, convergence and domain size you need. If your sensitivity analysis says you must go finer but you are at the limits of your license then your simulation is impossible. You should report that the simulation is not possible with available resources and spend your time doing something which is possible.

urosgrivc February 19, 2019 06:00

50 inflation layers sounds a lot, personally I think it is too much.
make sure to have a nice transition from inflation to tets with not too much difference in the thickness, and an aspect ratio of the first layer below 150, in this case, it works quite nicely. Try 20 layers, if this makes the transition good enough you will save some elements.

tyw7 February 19, 2019 06:18

I use first layer thickness. Is that not adequate? Or is there a better way?

urosgrivc February 19, 2019 06:23

Let us just say that there are infinite ways ;) some are good some are bad

And the correct thickness is actually dependant on a few factors
#Y+
#stage of flow developement
#aspect ratio
#turbulent models
#near wall region
#velocity near wall
#heat transfer (for those who use it)
#...


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