# [LES]how to learn large eddy simulation from scratch alone?

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 October 29, 2013, 09:41 [LES]how to learn large eddy simulation from scratch alone? #1 Member   garry Join Date: Oct 2013 Posts: 36 Rep Power: 4 dear all： i am a first year graduate. my teacher let me learn les now, but there is nobody had learned about it in our research group. i have learned cfd and les about two months, but the progress is little. now i am reading the book "Large Eddy Simulation for Incompressible Flow", and i realize that from scratch to les code is a long way. i want to know how can i learn les fast and what i should do now???

October 29, 2013, 10:11
#2
Senior Member

Filippo Maria Denaro
Join Date: Jul 2010
Posts: 1,856
Rep Power: 25
Quote:
 Originally Posted by yzeyue dear all： i am a first year graduate. my teacher let me learn les now, but there is nobody had learned about it in our research group. i have learned cfd and les about two months, but the progress is little. now i am reading the book "Large Eddy Simulation for Incompressible Flow", and i realize that from scratch to les code is a long way. i want to know how can i learn les fast and what i should do now???

The learning processs of LES is not simple, in no way can be fast, it requires time and effort.
You must start having good basis of CFD, mathematics, fluid dynamics.
Attending some courses is mandatory, also because you can have contacts with people and compare yourself.
Generally, my opinion is that preparing a person in the LES field is a PhD contest.

 October 29, 2013, 10:11 #3 Senior Member     Paolo Lampitella Join Date: Mar 2009 Location: Italy Posts: 537 Blog Entries: 14 Rep Power: 17 My opinion is that there is no fast in learning LES. It is a field where numerics meets physical modeling leading to infinity^2 possibilities. Also, there is a lot of personal flavour and much less detailed explanations. The basis, of course, is very simple: you have to resolve any dynamically significant scale. You can start by reading Sagaut, Lesieur, Garnier, Pope... but then you have to go back and start again, and again while getting practical experience. Still, the basis is as simple as adding a grid based mixing length model to a non diffusive 2nd order finite difference code for 3D unsteady Navier-stokes equations.

 October 29, 2013, 22:26 #4 Member   garry Join Date: Oct 2013 Posts: 36 Rep Power: 4 FMDenaro and sbaffini thank you. in my opinion, after a general understanding, learn les from a simple code may be better for the understanding of the process. is it right?

October 30, 2013, 04:29
#5
Senior Member

Filippo Maria Denaro
Join Date: Jul 2010
Posts: 1,856
Rep Power: 25
Quote:
 Originally Posted by yzeyue FMDenaro and sbaffini thank you. in my opinion, after a general understanding, learn les from a simple code may be better for the understanding of the process. is it right?

No ... studyng an LES code you learn only how one formulution is implemented, which is, actually, only a step in a learning process of LES.
As Paolo said, when you try to implement a simple LES code, it is common you need to come back to some theoretical questions and so on ...

To tell the true, if you want to become just a code user, then just learn how using Fluent by the handbook. Learning LES is a totally different issue.
Good luck

 October 30, 2013, 06:07 #7 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 1,856 Rep Power: 25 ... Great! Today wheater is good to go on the beach sbaffini likes this.

 October 30, 2013, 06:49 #8 Senior Member     Paolo Lampitella Join Date: Mar 2009 Location: Italy Posts: 537 Blog Entries: 14 Rep Power: 17 You can think of LES as assembling IKEA stuff. On the paper, it is very clear and you don't see any problem coming. Then you end up putting much more effort than planned, wasting most of your time, your hands broken. Every box is full of warnings, but you think they are for childs and you don't care. No single piece fits the others as expected. Even in the end, when the thing is built and it actually works, you have probably done something wrong, but it works, so who cares? plucas likes this.

 October 30, 2013, 09:18 #9 Member   garry Join Date: Oct 2013 Posts: 36 Rep Power: 4 haha, funny man. But, it sounds really helpful. Thanks. There is an old saying in China--haste makes waste.

 Tags beginner, cfd, learner, les

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