WebGPU · Large-Eddy Simulation
3D CFD Lab
A three-dimensional D3Q19 Lattice Boltzmann solver with a Smagorinsky LES closure on your GPU via WebGPU compute shaders. The domain is a wide viewing plane with a thin periodic spanwise slab — the minimum depth that still permits vortex stretching, the mechanism of real turbulence. It looks like a 2D simulation; it is not. Slide the span position to see the flow differ from plane to plane once the wake goes three-dimensional.
A spanwise cylinder in a thin periodic slab — beyond Re ≈ 190 the vortex street develops genuine 3D mode-A/B instabilities along the span.
About this simulation
D3Q19 BGK collision with a Smagorinsky subgrid model — in 3D this is a genuine (if coarse) large-eddy simulation. The spanwise direction is periodic (≈1.2 diameters deep), walls use half-way bounce-back, the inlet ramps up softly, and sponge zones absorb acoustics at both ends. What you see is a single z-plane, bilinearly interpolated; below Re ≈ 190 every plane looks identical (the flow stays 2D), and beyond it the planes visibly decorrelate — that difference is the onset of three-dimensionality. Still qualitative: resolution far below DNS, staircase walls, finite Mach number.