FSI & Particle Methods
Fluid–structure interaction, immersed boundaries and particle methods such as SPH for moving bodies in flow.
5 parts · 2026.04.29 – 2026.08.13
- 01
SPH Without Tears — Solving Fluids with Particles, from Kernel to Artificial Viscosity
With γ = 7, Tait turns a 1% density error into a large pressure swing, and a pressure gradient that is not symmetrized leaks pair momentum.
2026.04.29
- 02
A Heart Valve Without a Body-Fitted Mesh — Peskin's Immersed Boundary Method and the Discrete Delta
Peskin's four-point delta sums to one on the grid. The listing's 24 markers on a radius-8 cylinder sit more than two cells apart, so the wall stays gappy.
2026.05.15
- 03
When a Bullet Passes Straight Through a Wall — Continuous Collision Detection by Inclusion Bisection
An endpoint test says MISS when the crossing sits at t*=0.50000. Inclusion bisection brackets that root in 53 boxes at δ=1e-4 and does not skip the hit.
2026.06.08
- 04
A Wall the Grid Never Sees — IBM Delta Kernels and Multi-Direct Forcing
One forcing pass leaves 64% of free-stream slip on a cylinder. At Δs/h = 3 the gap slip hits 0.287, and at 0.25 the condition number reaches 1e11.
2026.08.03
- 05
The Weight Sits on Top and She Still Rights Herself — Metacentric Height and the Free Surface Effect
Capsizing is not decided by whether the centre of gravity sits above the buoyancy centre. The second moment of the waterplane, through GM, decides it.
2026.08.13