Kelvin-Helmholtz instability

Examples of flow modelling using Code_Saturne.
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Jean Deschodt

Kelvin-Helmholtz instability

Post by Jean Deschodt » Fri May 14, 2010 3:34 pm

A simplified Kelvin Helmholtz instability was simulated. Dry air filled up the upper half of the domain, and humid air the lower half. A 4% difference of density was assumed between the two gas. 2 m/s difference in velocity across the interface was fixed. The inlet velocity of the dry air was perturbed with a sinusoidal signal in order to generate the instability.
Attachments
cs_kelvinhelmholtz_example.gif

Jean Deschodt

Re: Kelvin-Helmholtz instabilities

Post by Jean Deschodt » Fri May 14, 2010 3:46 pm

Files to reproduce the case with Code_Saturne 2.0-rc1 :
Attachments
usiniv-f90.gz
(2.91 KiB) Downloaded 57 times
kelvin-med.gz
(1.18 MiB) Downloaded 60 times
instabilities-xml.gz
(1.88 KiB) Downloaded 68 times

David Monfort

Re: Kelvin-Helmholtz instability

Post by David Monfort » Sun May 16, 2010 5:44 pm

Hello Jean,
This is a really nice example here!
However, you might have better results with symmetries farther from the middle (haven't try though...). It seems you have some "blocking effect" due to the presence of the symmetries at bottom and top.
David

Jean Deschodt

Re: Kelvin-Helmholtz instability

Post by Jean Deschodt » Fri May 21, 2010 11:21 pm

I redo the computation with a wider inlet. Indeed, it changes the flow a little.  I redo also the set up without usini1.f90: everything was done by the GUI. I upload the new files below.
Attachments
kelvin-xml.gz
(1.93 KiB) Downloaded 69 times
kelvin-helmholtz-med.gz
(3.56 MiB) Downloaded 57 times
cs_kelvinhelmholtzlarge_example.png

Claus Andersen

Re: Kelvin-Helmholtz instability

Post by Claus Andersen » Sat Nov 20, 2010 1:26 pm

I thought the attached picture was relevant to this post went I came across it - I assume it's the described phenomena?
Regards,
Claus
Attachments
Kelvin-helmholtz.jpg

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