Kelvin-Helmholtz instability

Examples of flow modelling using Code_Saturne.
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Jean Deschodt

Kelvin-Helmholtz instability

Post by Jean Deschodt »

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 »

Files to reproduce the case with Code_Saturne 2.0-rc1 :
Attachments
usiniv-f90.gz
(2.91 KiB) Downloaded 151 times
kelvin-med.gz
(1.18 MiB) Downloaded 157 times
instabilities-xml.gz
(1.88 KiB) Downloaded 162 times
David Monfort

Re: Kelvin-Helmholtz instability

Post by David Monfort »

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 »

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 161 times
kelvin-helmholtz-med.gz
(3.56 MiB) Downloaded 158 times
cs_kelvinhelmholtzlarge_example.png
Claus Andersen

Re: Kelvin-Helmholtz instability

Post by Claus Andersen »

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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