# Kelvin Helmholtz instability

**URL:** <https://community.freefem.org/t/kelvin-helmholtz-instability/2305>\
**Category:** General Discussion\
**Created:** [March 2, 2023, 5:49pm UTC](https://community.freefem.org/t/kelvin-helmholtz-instability/2305 "2023-03-02T17:49:45Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![tle](https://avatars.discourse-cdn.com/v4/letter/t/898d66/32.png) [@tle](https://community.freefem.org/u/tle)\
**Post date:** [March 2, 2023, 5:49pm UTC](https://community.freefem.org/t/kelvin-helmholtz-instability/2305/1 "2023-03-02T17:49:45Z")

</div>

Hi, everyone. I want to ask if any one has tried to simulate the Kelvin Helmholtz instability? I dont know how to deal with the interface between two fluids.

---

<div class="post-metadata">

**Author:** ![marchywka](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@marchywka](https://community.freefem.org/u/marchywka)\
**Post date:** [March 2, 2023, 8:35pm UTC](https://community.freefem.org/t/kelvin-helmholtz-instability/2305/2 "2023-03-02T20:35:56Z")

</div>

For something like this, have you tried a literature search? I’m just answering because  
I’m curious about a lot of things like this. There seem to be many techniques for dealing  
with deformable interfaces. I guess there is always the issue between microscopic and macrosopic  
approach but presumably you are interested in the macroscopic and start with  
the usual suspects- F-ma at the interface, momentum conservation, divergence theorem etc.  
Writing an expression for the interface location may give you some ideas what is important  
presumably local curvature stuff like that. I guess if you found a few papers that seem  
to come close you could bring them here and see if anyone knows how they work  
with FF.