Dear Fellow Scholars, this is Two Minute Papers with Dr. Károly Zsolnai-Fehér.
Today we are going to put a fluid simulation in another fluid simulation and with that,
create beautiful videos like this one.
But how? And more importantly, why? Well, let’s take two fluid simulation techniques,
one will be the fluid implicit particle, FLIP, and the other will be the boundary element
method. BEM. But, why do we need two or perhaps even more methods, why not just one?
Well, first, if we wish to simulate turbulence and high-frequency splashes near moving objects,
FLIP is the answer. It is great at exactly that. However, it is not great at simulating
big volumes of water.
No matter, because there are other methods to handle that, for instance, the boundary
element method that we just mentioned, BEM in short. It is great in these cases because
the BEM variant that’s been used in this paper simulates only the surface of the liquid,
and for a large ocean, the surface is much, much smaller than the volume.
Let’s have a look at an example. Here is the pure FLIP simulation. This should be great
for small splashes. Yes, that is indeed true, but, look, the waves then disappear quickly.
Let’s look at what BEM does with this scene…yes, the details are lacking, but the waves are
lovely. Now we have a good feel of the limitations of these techniques - small splashes, FLIP,
oceans, BEM, got it. But, here is the problem… what if we have a scene where we have both?
Which one should we use?
This new technique says, well, use both! What is this insanity? Now, hold on to your papers,
and look! This is the result of fusing the two simulation techniques together. Now, if
you look carefully, yes, you guessed it right. Within the box, there is a FLIP simulation,
and outside of the boxes, there is a BEM simulation. And the two are fused together in a way that
the new method really takes the best of both worlds. Just look at all that detail. What
a beautiful simulation. My goodness.
Now, this is not nearly as easy as slapping together two simulation domains. Look, there
is plenty of work to be done in the transition zone.
And also, how accurate is this? Here is the reference simulation for the water droplet
scene from earlier. This simulation would take forever for a big scene and is here for
us to know how it should look. And, let’s see how close the new method is to it. Whoa.
Now we’re talking!
Now, worry not about the seams, they are there for us to see the internal workings of the
algorithm, the final composition will look like this.
However, not even this technique is perfect, as a potential limitation, look! Here is the
new method, compared to the reference footage. The waves in the wake of the ship are simulated
really well, and so are the waves further away at the same time. That’s amazing! However,
what we don’t get is, look, crisp details in the BEM regions. Those are gone. However,
just compare the results to this technique from a few years ago and to get a feel of
how far we have come just a couple papers down the line. The pace of progress in computer
graphics research is through the roof. Loving it. What a time to be alive!
And, let’s see, yes, the first author is Libo Huang. Again. If you are a seasoned Fellow
Scholar, you may remember our video on his first paper on ferrofluids. And, this is his
third one. This man writes nothing but masterpieces. As a result, this paper has been accepted
to the SIGGRAPH ASIA conference, and being a first author there is perhaps the computer
graphics equivalent of winning the olympic gold medal. It is also beautifully written,
so make sure to check it out in the video description. Huge congratulations on this
amazing work. I cannot believe that we are still progressing so quickly year after year.
Thanks for watching and for your generous support, and I'll see you next time!