Sending the smoke down 1 m cost 7 Pa of draft — Franklin's stove and the buoyancy budget
The chimney top never moves, yet one descending leg breaks the draft. We write out the buoyancy ledger, then find the fire temperature at which smoke spills into the room.
Viscosity Is Not What Kills a Vortex — Newton's 1/r and the Lamb–Oseen Core
A free vortex carries huge shear stress and still refuses to decay. The core and the wall hold the clock.
Four Shocks Beat One — The Oblique Shock Train in a Supersonic Inlet
Why several weak oblique shocks cost far less stagnation pressure than one strong shock
How Far Must Water Flow Before It Becomes a Parabola — Entrance Length and Hagen–Poiseuille
The pipe entrance region, the Hagen–Poiseuille parabola, and the 64/Re friction factor
A Single Ripple Outruns Its Own Group — Wave Dispersion and Group Velocity
Why every wavelength travels at its own speed, and phase and group part ways
Why a Spinning Ball Curves — the Magnus Effect and Circulation
How a single spin bends a ball's path, explained through circulation
Waves Hanging in the Sky — The Kelvin-Helmholtz Instability
Why two streams at different speeds roll up into vortices
Chaos That Begins at the Bottom of a Pot — Rayleigh–Bénard Convection and the Lorenz Equations
The moment buoyancy beats viscosity, and how convection rolls become chaos
The Shock Wave in Your Kitchen Sink — Froude Number and the Hydraulic Jump
Specific energy, critical depth, and the shallow-water to gas-dynamics analogy
Why Gasoline Engines Stop at a Compression Ratio of 12 — Otto vs Diesel
Air-standard cycles on compression ratio, engine efficiency, and the knock wall
Measure the Drag, Get the Heat Transfer — The Reynolds Analogy
Why friction and heat obey the same equation, and St·Pr^(2/3)=Cf/2
To Go Supersonic, Widen the Pipe — The De Laval Nozzle and Choking
From the area-Mach relation to the seven nozzle-flow regimes
Why Droplets Are Round and Water Climbs the Glass — Surface Tension and Contact Angle
From the physics of surface tension to contact angle and the CSF model in CFD
Heating It Hotter Made It Cooler — The Boiling Curve and Critical Heat Flux
The boiling-curve paradox: heat past the boiling point and heat transfer collapses
Why a Rougher Ball Flies Farther — The Drag Crisis and Boundary-Layer Separation
The cliff-like drop in $C_D$ called the drag crisis, and the separation behind it
Fluid That Warms Up While Standing Still — Natural Convection and Rayleigh 1708
The threshold where buoyancy beats viscosity, and the Nusselt correlations
Turbulence Runs Three Rulers at Once — The Kolmogorov Cascade and the -5/3 Law
How big eddies break down to viscous prey, and the spectrum drawn over that road
Three Portraits of a Flow — Why Streamlines, Pathlines, and Streaklines Diverge
Three curves that split apart in unsteady flow, and the material derivative
Why Smokestack Plumes Curl Up Instead of Lying Flat — The Jet in Crossflow and Its Counter-Rotating Vortex Pair
Why a jet fired across a wind folds into a kidney-shaped vortex pair.
Two Functions Added, and a Cylinder Appeared — Complex Potential and d'Alembert's Paradox
Why a uniform stream plus one tiny point gives you cylinder flow for free.
Above Mach 1, You Must Widen to Speed Up — The Laval Nozzle Paradox
When flow crosses sound speed, nozzles and diffusers swap jobs. We trace that one-line identity.
When the Stream Breaks — Reynolds' Critical Number and the Layered Turbulent Boundary
Where laminar flow falls apart, and how the turbulent boundary stacks itself in three sublayers
Water Boils at 20°C Too — The Physics of Cavitation
How depressurization makes water boil, the cavitation number, and the 10,000-bar collapse.
Two Faces of a Whirl — Free Vortex, Forced Vortex, and Helmholtz
From a bathtub drain to a tornado, what vorticity actually measures
Why Water Streams Break into Droplets — Plateau–Rayleigh Instability and Breakup Regimes
The principle of surface tension fragmenting liquid jets into droplets and the dimensionless map of spray design.
Bugs Swim in Honey — The World of Flow Changed by Reynolds Number
The Reynolds number revealed by non-dimensionalization, and how scale creates differences in flow.