Oceananigans is used for climate modelling and they use a different set of equations for this purpose (hydrostatic Boussinesq equations instead of Navier-Stokes equations). On the other hand, the numerical method both use is the same, finite volume, and the way we have CPU and GPU execution is using KernelAbstractions.jl in both cases too.

You are right. Ideally we would like to keep everything in GPU memory of course. But we have not been able to render CuArrays with Makie yet, and I'm not sure if that is actually implemented, as you suggest. If so, it would be great to see an example of this :)

As long as you can define a signed distance function, and the function governing the motion of the propeller, WaterLily can simulate it!

What turbulence models do you have implemented? It's been ~ a decade since I played with CFD, wondering if DNS is computationally tractable these days.

There is no explicit LES model, aka implicit LES. All the additional dissipation required when running coarse meshes relies on the numerical dissipation of the implemented schemes.

DNS is not used much (at all?) for real world problems, but LES has become much more common.

I don’t think that’s true. What about cavitation?

Cavitation has nothing special other than multi-phase flow. And implementing a VOF method is definitely in our roadmap. You can currently simulate it without cavitation to get a feeling of the unsteady flow solution, or wait for us to implement VOF.

Cavitation is precisely what I would like to test...

Also, will 'waterlilly' work with a viscosity to Air?

Meaning - toroidal props are a newer entering thing in drones... and I'd like to find out if the above applies equally to fluid/air?

Then you should is a different solver that fills your needs. WaterLily is an incompressible flow solver that works in non-dimensional units (assuming constant unit density). So you can change the viscosity of the fluid by modifying the Reynolds number (with set a set characteristic velocity and length scale).