Bluff Body Mach 2 3D — SLIP penalty — 400³

Wake slice (yz, at i = 0.75·N)
Cross-section perpendicular to the flow, just downstream of the body. Colour = density (blue ⟶ white ⟶ red, ρ ∈ [0.5, 1.5]). Black dots: p5-style particle traces of the in-plane (v_y, v_z) flow with fading comet tails. Reveals the 3D wake vortex structure (recirculation, plume cores) that the xy slice can't show.

shape: Substeps/frame: 3 art visc ν (×h): 0.10 shock visc C (μ += C·h·|−∇·u|): 1.0 diff μ (Lap smoothing on ρ,e,m): 0.10 Mach M (= u_inflow / c): 2.0 seed every (frames): 50 trace speed (×): 1000 slice z (main view, 0–1): 0.50 t = 0.000

Initializing WebGPU…

Bluff-body flow at Mach 2 in 3D, compressible Navier–Stokes, WebGPU. Uniform inflow ρ = 1, e = 1, v_x = 1 from the left. A cubic body of side 0.25 N centred in the domain acts as a hard no-slip wall (frozen ρ, e; zero momentum). Fluid cells adjacent to the body see a zero-momentum / matching-ρ-e ghost.

Display: mid-z slice (xy plane through the centre of the box). Colour = density (blue low → white mid → red high), tuned to ρ ∈ [0.5, 1.5]. Body cells overlaid in yellow.

Equations: ∂ρ/∂t + ∇·(ρv) = 0; ∂(ρv)/∂t + ∇·(ρv⊗v) + ∇p = ∇·σ; ∂e/∂t + ∇·(e v) + p∇·v = 0; p = γe, γ = 0.2; ν = 0.3 h.

Grid: 400³ = 64 000 000 cells. State packed as 8 floats per cell (5 data: ρ, e, m_x, m_y, m_z; + 3 pad); ping-pong storage buffers of 1.91 GiB each. Requires maxStorageBufferBindingSize ≥ 2 GiB from the adapter — at the absolute ceiling of what Apple Silicon / desktop dGPUs expose. M4/M3 Pro/Max and recent NVIDIA/AMD desktop typically pass; everything else will refuse with a clean error. Total GPU memory footprint ≈ 4.3 GB (two state buffers + mask + extracts).