4 ms·

Simulating Fluid Dynamics with Cellular Automata (1986) [pdf]

79 points by eigenvalue 6y ago

atemerev 6y ago
And now, lattice Boltzmann methods are completely mainstream, and are used everywhere in a huge variety of contexts. I was coding a LB simulation of virus carrying aerosol particles with OpenLB just a few hours ago :)
- conformist 6y ago
  Exactly, Wolfram's work is kind of an early(ish) predecessor of LBMs. For a more general introduction into lattice-based methods (that also references Wolfram's paper) see also here: https://www.annualreviews.org/doi/abs/10.1146/annurev.fluid.30.1.329 https://www.annualreviews.org/doi/abs/10.1146/annurev.fluid.... (A full pdf can be found online, too.)
  - yesenadam 6y ago
    PDF https://www.academia.edu/download/5772703/annurev.fluid.30.1.329.pdf https://www.academia.edu/download/5772703/annurev.fluid.30.1...
- lldbg 6y ago
  Well known in academia, but what type of industrial applications is it used in? To my knowledge most mainstream software suites run plain old RANS finite volume schemes.
  - hvocode 6y ago
    I’ve seen people speak about applications of LBM-based models in medical contexts like modeling blood in arteries with complex geometries. You can see applications on the pages for OpenLB and Palabos, which I believe are some of the more mature implementations of Lattice Boltzmann. Unfortunately it’s a bit hard to find references to industrial users since in my experience most industrial users don’t advertise the methods that they are using. I usually would find out about them by meeting people from industry at conferences where these tools would be talked about like the SIAM conferences and HPC conferences like SuperComputing. At one of my old jobs where some folks were implementing parallel LBM tools one of our major industrial partners came from the petroleum industry, and they were interested in flow through complex geometries to model fluids + porous rocks.
  - derjames 6y ago
    PowerFlow from EXA/Dassault uses LB. It is widely used in the automotive industry mostly for aerodynamics simulations.
failrate 6y ago
If this is interesting, I recommend joining the Patreon for Loren Schmidt. They create really beautiful CA projects, including environments with humidity/precipitation.
- jawarner 6y ago
  Yes, and follow the latest work of Alexander Mordvintsev, e.g.: https://distill.pub/2020/growing-ca/ https://distill.pub/2020/growing-ca/
chronolitus 6y ago
I remember having to code a 2d Lattice Boltzmann fluid simulator in Matlab for a college course, how fun and interesting that was! https://github.com/danieldugas/Lattice-Boltzmann-Simulation/blob/master/LBProjectReport.pdf https://github.com/danieldugas/Lattice-Boltzmann-Simulation/...
Lerc 6y ago
I implemented a form of this in JavaScript. Worked reasonably well. http://blag.fingswotidun.com/2015/10/hex-cellular-automata.html http://blag.fingswotidun.com/2015/10/hex-cellular-automata.h...
- eigenvalue 6y ago
  This looks awesome. I want to see if I can boost the resolution easily.
- pengaru 6y ago
  Neat! Works well here, it'd prolly look much better w/bilinear interpolation sampling the cell states per-pixel.
rxm 6y ago
Amazing things can happen when cellular automata have symmetries. Conserve number and momentum and you're a few steps from the HPP gas [0]. Make the momentum flow a bit more isotropic, and you are on your way to the FHP gas [1]. The history I remember is that Hasslacher and Wolfram had overlapped at the IAS early 1980s. On the summer of 1985 Hasslacher visited Frisch in Nice. It was there that they guessed that the hexagonal lattice might brake the strange conservation laws of HPP. After that it was a few days until they had a set of rules for the lattice gas fluid in 2d. From France Hasslacher called Shimomura at Los Alamos and asked him if could implement them. In a few days Shimomura has a crowd staring at his screen watching a simulation of a fluid flow past an obstacle shedding vortices in real simulation time. We can do that today with our smartphones, but at the time it must have been a first. [0]: Hardy, Pomeau, & Pazzis (1973) JMP: 10.1063/1.1666248 [1]: Frisch, Hasslacher, & Pomeau (1986) PRL: 10.1103/PhysRevLett.56.1505
jolincost 6y ago
It would be cool if cellular automata could create the factor trees of natural numbers

79 points by eigenvalue 6y ago

And now, lattice Boltzmann methods are completely mainstream, and are used everywhere in a huge variety of contexts. I was coding a LB simulation of virus carrying aerosol particles with OpenLB just a few hours ago :)

conformist 6y ago
Exactly, Wolfram's work is kind of an early(ish) predecessor of LBMs. For a more general introduction into lattice-based methods (that also references Wolfram's paper) see also here: https://www.annualreviews.org/doi/abs/10.1146/annurev.fluid.30.1.329 https://www.annualreviews.org/doi/abs/10.1146/annurev.fluid.... (A full pdf can be found online, too.)
- yesenadam 6y ago
  PDF https://www.academia.edu/download/5772703/annurev.fluid.30.1.329.pdf https://www.academia.edu/download/5772703/annurev.fluid.30.1...
lldbg 6y ago
Well known in academia, but what type of industrial applications is it used in? To my knowledge most mainstream software suites run plain old RANS finite volume schemes.
- hvocode 6y ago
  I’ve seen people speak about applications of LBM-based models in medical contexts like modeling blood in arteries with complex geometries. You can see applications on the pages for OpenLB and Palabos, which I believe are some of the more mature implementations of Lattice Boltzmann. Unfortunately it’s a bit hard to find references to industrial users since in my experience most industrial users don’t advertise the methods that they are using. I usually would find out about them by meeting people from industry at conferences where these tools would be talked about like the SIAM conferences and HPC conferences like SuperComputing. At one of my old jobs where some folks were implementing parallel LBM tools one of our major industrial partners came from the petroleum industry, and they were interested in flow through complex geometries to model fluids + porous rocks.
- derjames 6y ago
  PowerFlow from EXA/Dassault uses LB. It is widely used in the automotive industry mostly for aerodynamics simulations.

failrate 6y ago

If this is interesting, I recommend joining the Patreon for Loren Schmidt. They create really beautiful CA projects, including environments with humidity/precipitation.

jawarner 6y ago
Yes, and follow the latest work of Alexander Mordvintsev, e.g.: https://distill.pub/2020/growing-ca/ https://distill.pub/2020/growing-ca/

chronolitus 6y ago

I remember having to code a 2d Lattice Boltzmann fluid simulator in Matlab for a college course, how fun and interesting that was! https://github.com/danieldugas/Lattice-Boltzmann-Simulation/blob/master/LBProjectReport.pdf https://github.com/danieldugas/Lattice-Boltzmann-Simulation/...

Lerc 6y ago

I implemented a form of this in JavaScript. Worked reasonably well. http://blag.fingswotidun.com/2015/10/hex-cellular-automata.html http://blag.fingswotidun.com/2015/10/hex-cellular-automata.h...

eigenvalue 6y ago
This looks awesome. I want to see if I can boost the resolution easily.
pengaru 6y ago
Neat! Works well here, it'd prolly look much better w/bilinear interpolation sampling the cell states per-pixel.

rxm 6y ago

Amazing things can happen when cellular automata have symmetries. Conserve number and momentum and you're a few steps from the HPP gas [0]. Make the momentum flow a bit more isotropic, and you are on your way to the FHP gas [1]. The history I remember is that Hasslacher and Wolfram had overlapped at the IAS early 1980s. On the summer of 1985 Hasslacher visited Frisch in Nice. It was there that they guessed that the hexagonal lattice might brake the strange conservation laws of HPP. After that it was a few days until they had a set of rules for the lattice gas fluid in 2d. From France Hasslacher called Shimomura at Los Alamos and asked him if could implement them. In a few days Shimomura has a crowd staring at his screen watching a simulation of a fluid flow past an obstacle shedding vortices in real simulation time. We can do that today with our smartphones, but at the time it must have been a first. [0]: Hardy, Pomeau, & Pazzis (1973) JMP: 10.1063/1.1666248 [1]: Frisch, Hasslacher, & Pomeau (1986) PRL: 10.1103/PhysRevLett.56.1505

jolincost 6y ago

It would be cool if cellular automata could create the factor trees of natural numbers