How Far Must Water Flow Before It Becomes a Parabola — Entrance Length and Hagen–Poiseuille
·4 min read
The pipe entrance region, the Hagen–Poiseuille parabola, and the 64/Re friction factor
Measure the Drag, Get the Heat Transfer — The Reynolds Analogy
·5 min read
Why friction and heat obey the same equation, and St·Pr^(2/3)=Cf/2
Why a Rougher Ball Flies Farther — The Drag Crisis and Boundary-Layer Separation
·5 min read
The cliff-like drop in $C_D$ called the drag crisis, and the separation behind it
When the Stream Breaks — Reynolds' Critical Number and the Layered Turbulent Boundary
·7 min read
Where laminar flow falls apart, and how the turbulent boundary stacks itself in three sublayers