Set by the pipe Reynolds number — internal flow, not a wake

• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before and 40 m after the meter; valve shut in 5 ms; no pipe friction · venturi-claim · hero
• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before and 40 m after the meter; valve shut in 5 ms; no pipe friction · venturi-claim
• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before and 40 m after the meter; valve shut in 5 ms; no pipe friction · venturi-claim
• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before and 40 m after the meter; valve shut in 5 ms; no pipe friction · venturi-claim
• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before the meter and 20, 40 or 80 m after; valve shut in 5 ms; no pipe friction · venturi-claim
• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before and 40 m after the meter; valve shut in 5 ms; no pipe friction · venturi-claim
• A choked throat buys time, not silence — 5 bar upstream, 25 mm lines, 20 m before and 40 m after the meter; valve shut in 5 ms; no pipe friction · venturi-claim
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — laminar Poiseuille · how-long-viscosity-remembers · hero
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — laminar Poiseuille · how-long-viscosity-remembers
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — laminar Poiseuille · how-long-viscosity-remembers
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — a uniform slab at the inlet, laminar Poiseuille · how-long-viscosity-remembers
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — laminar Poiseuille · how-long-viscosity-remembers
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — laminar Poiseuille · how-long-viscosity-remembers
• A duct that forgets everything but one number — 10 mm channel, water, 0.1 m/s — laminar Poiseuille · how-long-viscosity-remembers
• A number that is only the shape of the hole — the ten sections · regime-exact
• A number that is only the shape of the hole — fully developed laminar flow · regime-exact
• A puff that does not know how old it is — pipe flow, Reynolds numbers 1600 to 2400 · what-turbulence-forgets · hero
• A puff that does not know how old it is — pipe flow, Reynolds numbers 1600 to 2400 · what-turbulence-forgets
• A puff that does not know how old it is — pipe flow at Reynolds number 1900 · what-turbulence-forgets
• A puff that does not know how old it is — pipe flow at Reynolds number 1900 · what-turbulence-forgets
• A puff that does not know how old it is — pipe flow · what-turbulence-forgets
• A puff that does not know how old it is — pipe flow, Reynolds numbers 1600 to 2400 · what-turbulence-forgets
• A puff that does not know how old it is — pipe flow · what-turbulence-forgets
• A viscosity made of particles — fully developed laminar flow at one pressure gradient, so ∫Φ = GQ throughout · what-viscosity-is
• A viscosity that depends on the question — fully developed laminar flow — the flow index n is the only variable · what-viscosity-is · hero
• A viscosity that depends on the question — fully developed laminar flow — the flow index n is the only variable · what-viscosity-is
• A viscosity that depends on the question — fully developed laminar flow at one pressure gradient, so ∫Φ = GQ throughout · what-viscosity-is
• A viscosity that depends on the question — fully developed laminar capillary flow — the indices are quoted, not measured · what-viscosity-is
• A viscosity that depends on the question — fully developed laminar flow at one pressure gradient, so ∫Φ = GQ throughout · what-viscosity-is
• Slip is a memory of one mean free path — Knudsen number 0.05, full accommodation · which-memory-a-number-decides · hero
• Slip is a memory of one mean free path — Knudsen number 0.05, full accommodation · which-memory-a-number-decides
• Slip is a memory of one mean free path — Poiseuille flow with first-order slip, full accommodation · which-memory-a-number-decides
• Slip is a memory of one mean free path — Poiseuille flow with first-order slip · which-memory-a-number-decides
• Slip is a memory of one mean free path — air, full accommodation · which-memory-a-number-decides
• The angle a junction chooses — a symmetric bifurcation obeying Murray's law — Poiseuille flow in every segment · applied-total · hero
• The angle a junction chooses — splits from 2 to 50 per cent — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — a symmetric bifurcation obeying Murray's law — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — Murray's law imposed on the radii — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — at the Murray optimum, where the cost per length is proportional to r squared — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — four radius ratios obeying Murray's law — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — Murray's law imposed — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — a symmetric bifurcation — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — a symmetric bifurcation — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — the quoted ranges are quoted, not computed here — Poiseuille flow in every segment · applied-total
• The angle a junction chooses — a symmetric bifurcating tree — Poiseuille flow in every segment · applied-total
• The cheapest shape the walls allow — a channel with no slip at both walls — the amplitude is the only variable · energy-budget
• The core that does not move — unit pipe and unit pressure gradient, tau_y/tau_w from 0.2 to 0.95 · viscous-exact
• The core that does not move — a yield stress of 0.2 in a unit pipe · viscous-exact
• The core that does not move — unit pipe, unit pressure gradient, unit plastic viscosity · viscous-exact
• The fluid that has not finished its last deformation — fully developed laminar capillary flow — the indices are quoted, not measured · what-viscosity-is
• The margin friction lends a siphon — water at 20 °C — turbulent at the start, laminar in the last centimetres · siphon-profile · hero
• The margin friction lends a siphon — water at 20 °C — turbulent at the start, laminar in the last centimetres · siphon-profile
• The margin friction lends a siphon — water at 20 °C — pipe flow, turbulent in every bore at this drop · siphon-profile
• The margin friction lends a siphon — water at 20 °C — pipe flow, laminar in the narrowest bores, turbulent above a few millimetres · siphon-profile
• The margin friction lends a siphon — water at 20 °C — the transition band is interpolated, not measured · siphon-profile
• The profile a meter cannot see — fully developed and disturbed approach flows — pipe flow, incompressible · applied-total · hero
• The profile a meter cannot see — fully developed and disturbed approach flows — pipe flow, incompressible · applied-total
• The profile a meter cannot see — an editorial figure — pipe flow, incompressible · applied-total
• The profile a meter cannot see — the five profiles above — pipe flow, incompressible · applied-total
• The profile a meter cannot see — turbulent pipe flow · applied-total
• The profile a meter cannot see — beta = 0.6 — pipe flow, incompressible · applied-total
• The profile a meter cannot see — a 1/7 power-law target — pipe flow, incompressible · applied-total
• The profile a meter cannot see — the same pair — pipe flow, incompressible · applied-total
• The profile a meter cannot see — beta = 0.6 — pipe flow, incompressible · applied-total
• The profile a meter cannot see — an editorial figure — pipe flow, incompressible · applied-total
• The profile a meter cannot see — a fully developed laminar approach — pipe flow, incompressible · applied-total
• The stress a pipe knows — the same wall stress for all four — laminar pipe flow, fully developed · profile-and-total · hero
• The stress a pipe knows — fully developed flow, any fluid — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — the same wall stress for all four — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — power-law fluids from n = 0.2 to 1.5 — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — power-law fluids — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — power-law fluids at five indices — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — mu0 = 10, muInf = 0.1, lambda = 1, n = 0.4 — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — a Carreau fluid at three wall stresses — laminar pipe flow, fully developed · profile-and-total
• The stress a pipe knows — one wall stress — laminar pipe flow, fully developed · profile-and-total
• The swirl that holds a wave still — a pipe of radius R, swirl number S = Omega R/W · ideal-limit · hero
• The swirl that holds a wave still — a pipe of radius R, swirl number S = Omega R/W · ideal-limit
• The swirl that holds a wave still — uniform axial flow, Rankine core 1, unit pipe · ideal-limit
• The swirl that holds a wave still — uniform axial flow, Rankine core 0.5, unit pipe · ideal-limit
• The swirl that holds a wave still — solid-body swirl in a pipe, and shallow water in a channel · ideal-limit
• The swirl that holds a wave still — columnar vortices in a pipe, uniform axial flow · ideal-limit
• The swirl that holds a wave still — columnar vortices in a pipe · ideal-limit
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim · hero
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim
• The venturi that stops listening downstream — turbulent pipe flow in water — the throat reaches vapour pressure; the cavity is represented by the recovery it destroys · venturi-claim
• Twice the margin, on top of the hammer — turbulent pipe flow — friction factor 0 to 0.06, quasi-steady; H₀ = 25 m · surge
• Where a fluid stops being one — full accommodation, σ = 1; Kn on the gap · rarefied-channel · hero
• Where a fluid stops being one — full accommodation, σ = 1; Kn on the gap · rarefied-channel
• Where a fluid stops being one — full accommodation, σ = 1; Kn on the radius · rarefied-channel

Every regime · All figures · All essays