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Old   September 21, 2020, 04:29
Post Questions and Resources for Transition modelling
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Hello everyone,

I am an undergraduate student and I'm planning on simulating a 2-D Kelvin-Helmholtz instability as a personal project.
My experience with CFD is using Fluent and writing simple Finite Difference codes on python. But I have a pretty good understanding of the mathematics of numerical methods.
Unfortunately I am unable find any suitable resources that would help me go about transition. Could someone direct me to resources for the same.

1) Should I go for a simulation on openfoam? or are there better open source softwares available for transition? (On openfoam Re-theta -gamma is the only transition model afaik)
2) Should I write my own code on python/Matlab?
3) What transition models should I use? I understand DNS and LES would give the best results but since DNS is computationally expensive. I was planning on going for LES. I have a i7 9th gen 6 core laptop with 16 gb of ram. Would that be good enough for a good 2-D LES ?
4) How would my results be validated ?

Moreover what I expect to be the learning outcomes are to be able to write/edit code for my usage, be able to solve in parallel and get a good understanding of the physics of the problem.
Suggestions to model different cases would be welcome. Since I'm new to it, I don't know much.

Thank you
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Old   October 3, 2020, 18:08
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Pedro Costa
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Hi,


You can actually do a DNS on your laptop if you have a numerical algorithm (and implementation) that is fast enough. In particular, for a 2D problem it should be no problem to run it on a laptop. As for which tool to use, I think it does not matter so much for a simple 2D mixing layer to study the KH instability.



One tool that allows you for instance to simulate a turbulent channel flow on your laptop with is the DNS code CaNS (https://github.com/p-costa/CaNS). You can also easily use it for a 2D KH instability, as long as you implement the initial condition yourself .

Disclaimer: I am the author of CaNS .



The nature of the KH instability is inviscid and your results can be directly validated against linear stability theory (perhaps you can get access to the book of Darzin).
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