Tube Flow
A computational fluid dynamics lab that runs in your browser. Put a sphere, a wing section or your own shape in a tube of real fluid, and watch the flow develop in 3D while drag, lift and the wake are measured live, with results checked against exact solutions and the published literature.
What it does
- Sets up a real experimentAir, water, olive oil or glycerol mixtures, in a tube of real size, past a sphere, ellipsoid, cylinder, disc, cube, bar, NACA wing section or an imported STL shape, with steady or pulsing inflow.
- Solves the flow in 3DA lattice-Boltzmann solver on the graphics card (WebGPU), with the processor as fallback, fine enough to resolve vortex shedding behind the body.
- Measures what engineers needDrag and lift coefficients, Strouhal number, wake length, pressure drop and the surface pressure along a wing, as they happen.
- Makes the flow visibleDye, vortex surfaces, streamlines and movable cross-sections, with video recording.
- Supports studiesReynolds-number sweeps plotted against published curves, saved runs side by side, five guided labs, and export to CSV, JSON and VTK for ParaView.
How it is built
The solver uses a validated scheme: two-relaxation-time collision, curved-wall boundaries and inlets and outlets that conserve mass. A public validation report sets it against exact solutions, published results and conservation laws, with grid-convergence studies, and every case can be re-run in your browser. The graphics-card and processor solvers are tested to give the same answers.
Author
Tube Flow was designed and built by Daniel Alberto Sepulveda Estay, PhD, founder of Estay Dynamics. He works on simulation, system dynamics and optimisation for engineering and supply chain decisions. He holds a PhD from the Technical University of Denmark and an MSc from the Massachusetts Institute of Technology, and is a council member of the System Dynamics Society.
To cite: Sepulveda Estay, D. A. (2026). Tube Flow: a validated lattice-Boltzmann flow lab (version 6.2.2) [Software]. https://kathuman.github.io/claude-projects/tube-flow-sim/