PixelPhysics

Interactive physics based simulation of condensed phase.

https://bartbruininks.github.io/PixelPhysics/

(click the link or the image to launch the simulator directly from this repo)

Fig 1. Adhesion of a droplet to a surface

By locking the red field and making sure the blue field is in the liquid domain, we can create a droplet adhesion experiment. The shown wetting uses $CI_{ab} = 0.04$.

How to use

• Select a field by clicking on it
• Draw in the empty window by clicking and or dragging with left mouse button
• Remove pixels in the active field by starting on a filled pixel
• Start simple and draw a single pixel and step through the simulation using the individual step buttons
• Make a screenshot of a cool system and its settings and share it with us and your friends
• Sharing settings should be a breeze as you can simply share the url, the field positions are not saved in the url

Underlying algorithm

1. Each field ($F_i$) is a boolean grid with $N_i$ non-empty values
2. Each field is blurred using a gaussian kernal with a cutoff in $K$ successive iterations
3. The self interactions scale the blurred gaussian values
4. The cross interactions ($CI$) are calculated per pixel as $Fa_i += (0.5 - Fb_i) * CI_{ab} * 2$ if $0.1 < Fb_j < 1.0$ (interface like interaction)
5. For each pixel in each field a random Gumble value is added where the sample is based on the temperature.
6. Each field ($F_i$) is discretized by quickselect partitioning the field and picking the $N_i$ highest values (O(N) on average)

Thus far observed phenomena

It would be cool if we can create a set of examples which shows the following phenomena. Thus far I have shown these in presentations, but it would be really nice if we have a collection of them all with screenshots and their settings in our wiki. However, the exact settings might change as the code is still being developed. Nevertheless, having listed (with images/videos) all the cool things we can demonstrate would no doubt be useful.

• Amorphic solids
• Crystaline solids (squares and diamonds)
• Oswald ripening
• Liquids (with increased ruffling of their boundary with increasing temperature)
• Liquid-Gas / Solid-Gas phase coexistence (Thanks to Agur Sevink who pointed out my temperature was not correct!)
• (Non-)perfect gasses
• Droplets of defined size
• Treadmilling
• Vesicle formation
• MOFs (sponges)
• Adhesion/cohesion
• pH
• Cellular motion

How to contribute

• Create a discussion or issue on this repo and let us know what you have in mind
• Send a pull request
• The current code is a proper mess at it was a first attempt to program in collaboration with LLMs. Cleaning up the code should be the first priority!