VSPAERO - Periodic wake, Done creating vortex sheet data...

[Koaib Kaleem]

Hi,

already messaged but its not approved yet, but since i have some updates so posting this as well so anyone reviewing this question may look into it as well.

The problem is when i m running full aircraft analysis, a message "Done creating vortex sheet data..." comes and no results are generated. 

Can some kindly tell me what could be the reason behind this, in short whadt does this error generally means?

To debug this problem, I decide to gradually add components to figure out which component is actually problematic. (No changes in default vals, no mesh adjustement, just checekd if the ran analysis looks ok)

Thin set: wing, ht, vt, strakes

Thick set: cockpit, fuselage, nozzle

(model attached- the actual model will be sacled by 19)

 I started with wing, then added fuselage, then cockpit, then nozzle and then strake. till this point everything seemed reasonable. (SS attached-Screenshot 2026-07-25 213939.png (60k)

but when i added HT things started going wrong. The distribution seemed unsymmetrical. (unfortunateley i dont have the ss) but then when i reopend the vspaero it seemed coorect (ss attached-  Screenshot 2026-07-25 214939.png (159k))

(what could have caused this???)

Next i attached VT and then error came of periodic wake ... came and results mager shows no result (SS attached-  Screenshot 2026-07-25 215316.png (184k))

I treid running VT individually it is ok (ss attached- Screenshot 2026-07-25 215715.png (124k)

I tried running VT as thick as well, then it gives this error,

"There are:          6 Vortex Sheets
Creating vortex sheet data...
There are: 10 kutta nodes for sheet: 1
There are: 10 kutta nodes for sheet: 2
There are: 12 kutta nodes for sheet: 3
There are: 12 kutta nodes for sheet: 4
Warning ... zero kutta nodes for sheet: 5
There are: 5 kutta nodes for sheet: 6
Marking kutta node 1 on sheet 1 as concave
Marking kutta node 1 on sheet 1 as on thin/thick or thin/thin intersection
CoreWidth_: 0.010049
There are:         10 kutta nodes for vortex sheet:          1
Marking kutta node 1 on sheet 2 as concave
Marking kutta node 1 on sheet 2 as on thin/thick or thin/thin intersection
CoreWidth_: 0.010049
There are:         10 kutta nodes for vortex sheet:          2
Marking kutta node 11 on sheet 3 as on thin/thick or thin/thin intersection
CoreWidth_: 0.004558
There are:         12 kutta nodes for vortex sheet:          3
Marking kutta node 12 on sheet 4 as on thin/thick or thin/thin intersection
CoreWidth_: 0.004558
There are:         12 kutta nodes for vortex sheet:          4
CoreWidth_: 0.011689
There are:          5 kutta nodes for vortex sheet:          5
Done"

Fine grid tri 2 is: 180 with surface ID: 4

When i run ht and vt only the sam eeroor of periodic wake... comes with no result generated.

Can someone kindly help me figure this out

Thankyou

[Rob McDonald]

I don't know what exactly is causing the problem, but it is caused by the intersection of the VT and HT.

If you move the VT slightly inboard until it no longer intersects with the HT, then it runs OK.

You will still want to work with your tessellation resolution -- it is coarse in places.  But, once you get a first solution, you can start playing with it.

Rob

[Koaib Kaleem]

Also one more thing i wanted to ask, i was thinking of fist adjusting tess and see when the results become constant. and then set the wake iterations so the log convg is about -4 to -5.

is this a reasonable approach?

[Koaib Kaleem]

Right thanks, i just moved the ht a little bit and it worked, 

Yes i ll be working on my mesh now. but one thing i would like to ask first is my cl alpha is not straight line also the load dist plot seems unsymmetrical, is it because of the mesh resolution or maybe some other reason?

regards

On Sunday, July 26, 2026 at 9:30:16 AM UTC+5 Rob McDonald wrote:

[Koaib Kaleem]

Right thanks, i just moved the ht a little bit and it worked, 

Yes i ll be working on my mesh now. but one thing i would like to ask first is my cl alpha is not straight line also the load dist plot seems unsymmetrical, is it because of the mesh resolution or maybe some other reason?

regards

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