

Full Scale Simulation of SpaceX's Mars Rocket Engine [video] - iwwr
http://on-demand.gputechconf.com/gtc/2015/video/S5398.html

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backprojection
Does anyone know why they don't use more modern directional representation
systems, like curvelets, or shearlets?

My understanding is that they provide optimally sparse representation of this
type of data - data that's smooth except on these wavefront sets, and that
wavelets perform comparatively poorly.

[http://en.wikipedia.org/wiki/Shearlet](http://en.wikipedia.org/wiki/Shearlet)
[http://en.wikipedia.org/wiki/Curvelet](http://en.wikipedia.org/wiki/Curvelet)

~~~
nether
Maybe a huge amount of legacy code using wavelets that's been debugged and
experimentally validated. CFD code checking is laborious and errors often very
subtle, and so tends to be pretty conservative.

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RoboTeddy
here's the video file:
[http://s3-2u.digitallyspeaking.com/assets/nvidia/events/gtc1...](http://s3-2u.digitallyspeaking.com/assets/nvidia/events/gtc15/S5398_JUAD-
ve386a-1300.mp4)

(in case you want to watch at 2x speed in VLC or something)

~~~
mbostock
You can also watch it at 2x on YouTube:
[https://www.youtube.com/watch?v=vYA0f6R5KAI](https://www.youtube.com/watch?v=vYA0f6R5KAI)

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probdist
In case anyone's interest was piqued by the complicated reaction mechanisms
involved in even relatively simple combustion problems, you can automatically
generate these mechanisms using software called "Reaction Mechanism Generator"
[http://rmg.mit.edu/](http://rmg.mit.edu/) produced by a group in MIT's
department of Chemical Engineering.

You wouldn't want to have to determine parameters and pathways for a 53
species 300+ reaction mechanism except in a highly automated fashion.

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iwwr
I don't know why the title was changed. The talk is by Adam Lichtl and Stephen
Jones.

It features computer fluid dynamic (CFD) simulations of combustion in an
accessible manner, though naturally the details are quite complex under the
cover.

Keywords, for people wanting to dip their toes: discrete wavelet transform,
space partition schemes (BSP, quadrees, octrees), space-filling curves.

The point lookup technique was a little fuzzy and I'd like some more details
if possible.

~~~
dang
> I don't know why the title was changed.

The HN guidelines ask submitters not to change titles except when they are
misleading or linkbait. Accordingly, we often change an edited title back to
language used by the article itself—usually the original title, sometimes a
subtitle or other heading. One reason for this is that we can't judge the
accuracy of most edits.

HN titles also tend not to include the names of authors or speakers. We
learned years ago that the site works better when emphasis is on content, not
personalities.

(Submitted title was "SpaceX's GPU-Powered Combustion Simulation – Adam Lichtl
and Stephen Jones")

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ranman
I start at SpaceX on July 27th... I'm pretty stoked about that.

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e_modad
Congrats!

~~~
ranman
Thanks! Hopefully I'll have a nice post about what it's like to work there.

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manigandham
Over my head but still fascinating to watch (because I like space). Anyone
have good intros to this kind of simulation stuff?

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tanderson92
I am not sure there is a good "intro" for a lot of this per se since many of
these ideas tie to research topics in applied math. I will give a few books
that seem to touch on areas related:

* You first need a basic (or not so basic) numerical analysis course.

* For wavelets: Mallet's "A Wavelet Tour of Signal Processing"

* For spectral methods in general, a primer many people prefer is Trefethen's "Spectral Methods in MATLAB". It is introductory and you really should start here, but for its reliance on MATLAB and a matrix point of view it's not entirely practical.

* For GPU computing, a slightly advanced book is "The CUDA Handbook: A Comprehensive Guide to GPU Programming"

* For general-purpose parallel CPU computation: "Using MPI" by Gropp

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themgt
Just heard him say they based this on wavelet CFD work by Johnathan Regele
(basically GPU-optimizing: it)

[http://www.aere.iastate.edu/jregele/](http://www.aere.iastate.edu/jregele/)
[http://www.tandfonline.com/doi/abs/10.1080/10618560903117105](http://www.tandfonline.com/doi/abs/10.1080/10618560903117105)

[edit: see Acknowledgements at the end]

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verytrivial
I understood 99% of that. I have chosen the wrong career.

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wavesum
So where was the engine? All we saw was simulation of flow from a triangular
area that wasn't shaped anything like an engine nozzle.

So yeah... was expecting an engine. Saw a 2-dimensional triangle. Dissappoint.

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themgt
Would I be right in assuming there's no open source CFD apps capable of the
kind of demos he was doing? Any proprietary apps?

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chillingeffect
Openfoam and su2.

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dikaiosune
Transcript?

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spacefight
Laser Melting in space! Love it!

[https://www.additively.com/en/learn-about/laser-
melting](https://www.additively.com/en/learn-about/laser-melting)

