# Is a Realistic Honey Simulation Possible? 🍯

## Метаданные

- **Канал:** Two Minute Papers
- **YouTube:** https://www.youtube.com/watch?v=7SM816P5G9s
- **Дата:** 15.10.2019
- **Длительность:** 4:35
- **Просмотры:** 2,258,653
- **Источник:** https://ekstraktznaniy.ru/video/14237

## Описание

❤️ Check out Weights & Biases here and sign up for a free demo: https://www.wandb.com/papers

📝 The paper "A Geometrically Consistent Viscous Fluid Solver with Two-Way Fluid-Solid Coupling" is available here:
http://gamma.cs.unc.edu/ViscTwoway/

The Weights & Biases posts on the Witness (and code!) are available here:
https://www.wandb.com/articles/i-trained-a-robot-to-play-the-witness
https://github.com/wandb/witness

My earlier video on The Witness game:
https://www.youtube.com/watch?v=Ee9vF5eChhU

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## Транскрипт

### Physics simulations are amazing []

If we study the laws of fluid motion from physics, and write a computer program that contains these laws, we can create wondrous fluid simulations like the ones you see here. The amount of detail we can simulate with these programs is increasing every year, not only due to the fact that hardware improves over time, but also, the pace of progress in computer graphics research is truly remarkable. So, it s there nothing else to do? Are we done with fluid simulation research? Oh, no.

### More challenges [0:30]

No, no. For instance, fluid-solid interaction still remains a challenging phenomenon to simulate. This means that the sand is allowed to have an effect on the fluid, but at the same time, as the fluid sloshes around, it also moves the sand particles within. This is what we refer to as two-way coupling. Note that this previous work that you see here was built on the Material Point Method

### The new paper [0:54]

a hybrid simulation technique that uses both particles and grids, whereas this new paper introduces proper fluid-solid coupling to the simpler, grid-based simulators. Not only that, but this new work also shows us that there are different kinds of two-way coupling. If we look at this footage with the honey and the dipper, it looks great, however, this

### Honey simulation [1:15]

still doesn’t seem right to me. We are doing science here, so fortunately, we don’t need to guess what seems or doesn’t seem right. This is my favorite part, because this is when we let reality be our judge and compare to what exactly happens in the real world. So let’s do that! Whoa! There is quite a bit of a difference, because in reality, the honey is able to support the dipper. One-way coupling, of course, cannot simulate this kind of back and forth interaction, and neither can weak two-way coupling pull this off. And now, let’s see, YES! There we go, the new strong two-way coupling method finally gets this right. And not only that, but what I really love about this is that it also gets small nuances

### Even small nuances are correct [2:11]

right. I will try to speed up the footage a little, so you can see that the honey doesn’t only support the dipper, but the dipper still has some subtle movements both in reality and

### Adaptivity is hard [2:22]

in the simulation. A+. Love it. So, what is the problem? Why is this so difficult to simulate? One of the key problems here is being able to have a simulation that has a fine resolution in the areas where a fluid and a solid intersect each other. If we create a super detailed simulation, it will take from hours to days to compute, but on the other hand, if we have a too coarse one, it will compute the required deformations in so few of these grid points that we’ll get a really inaccurate simulation, and not only that, but we will even miss some of the interactions completely. This paper proposes a neat new volume estimation technique that focuses these computations

### A new method for it [3:06]

to where the action happens, and only there, which means that we can get these really incredible results, even if we only run a relatively coarse simulation. I could watch these gooey, viscous simulations all day long. If you have a closer look at the paper in the description, you will find some hard data that shows that this technique executes quicker than other methods that are able to provide comparable results. Thanks for watching and for your generous support, and I'll see you next time!