One Integral Read as 0.1406 and 56.91 — Torsion Stress Function and Duct Laminar Flow
·9 min read
A square bar's torsion constant and a square duct's f·Re are one Poisson solution read twice. One linear-triangle FEM run gives both handbook numbers.
How Far Must Water Flow Before It Becomes a Parabola — Entrance Length and Hagen–Poiseuille
·5 min read
In laminar pipe flow a flat inlet needs about 0.05 Re diameters to become a parabola, and 64/Re is not valid until that station.