This simulator builds Reynolds number from its physical ingredients — bore, velocity, density and viscosity — on a vertical test-loop rig, and lets you choose whether the imposed condition is mean velocity or volume flow so you can see exactly how each held-fixed choice changes the outcome of scaling up or down. Adjust the operating mode, velocity or flow target, internal bore, viscosity and density, and watch the inertia and viscosity stress scales and their ratio update together.
• A real-time 3D scene of the vertical circular test column, a bore caliper with a replaceable sleeve, a flow indicator and rotor housing, a fluid-property sample vessel and viscosity probe, an inertia/viscosity scale comparator with illuminated logarithmic bars, a return line with service pump and isolation hardware, and an operating-mode selector/calculation console, with home view, focus-selected-part, show-full-enclosure, exploded view, auto-rotate, expand and show/hide labels controls. • An Equipment laboratory tab with a labeled parts index (column, caliper, flowmeter, sample, scales, return, console) and click-to-inspect component callouts. • Six experiment controls: imposed operating quantity (hold mean velocity or hold volume flow), velocity target (0–1.5 m/s, velocity mode), flow target (0–20 L/min, volume-flow mode), internal test bore (5–100 mm), dynamic viscosity μ (0.5–50 mPa·s) and liquid density ρ (800–1,200 kg/m³). • Playback controls: pause/resume, advance 0.1 s, advance 1 s, and four playback speeds (10× slow motion, real time, 10× faster, 1 minute per second), plus start/stop animation, water-like-properties and viscous-liquid-properties preset actions. • A Curves & measurements tab with a diameter-sensitivity chart at the current imposed condition, two live charts (Reynolds number history, and inertial vs. viscous stress scales), the governing dimensional-analysis equations (Re definition, kinematic viscosity, fixed-velocity vs. fixed-flow scaling) and snapshot measurement readouts. • An Experiments tab with four guided fixtures (velocity-held baseline, double bore at fixed velocity, double bore at fixed volume flow, viscosity dominates) and a Model verification bench that runs independent deterministic checks against a fresh model without disturbing your live experiment, plus a timestamped event log and a copyable trial report. • A Learn & assess tab with guided lessons, a knowledge-check quiz with reset, and a written model-scope statement with a technical-background reference link.
Reynolds number is the ratio of an inertial stress scale (ρV²) to a viscous stress scale (μV/D) — both have units of pressure, and their ratio, ρVD/μ, is dimensionless. The simulator's illuminated scale comparator displays both stress scales side by side on a shared logarithmic axis, making it visually obvious that Reynolds number is exactly their ratio for nonzero flow, not two independently measured forces on the rig.
Which operating quantity you hold fixed matters enormously when you change bore size: at fixed velocity, Reynolds number scales directly with diameter (Re ∝ D), so doubling the bore doubles Re. But at fixed volume flow, velocity must fall as 1/D² to keep Q constant, so Reynolds number instead scales as 1/D — doubling the bore actually halves Re. The simulator's paired 'double bore' experiments demonstrate both outcomes side by side from the identical starting point.
The operating-mode console only lets you impose one quantity (velocity or volume flow) at a time — the unused target control is disabled, and switching modes recalls the stored target value for that mode, which can change the resulting duty. This deliberately forces you to be explicit about what your engineering problem is actually holding constant, since real specification and comparison mistakes often come from silently assuming the wrong fixed quantity.
This is a steady, Newtonian, incompressible-liquid model where Reynolds number uses mean velocity and internal diameter; the guide bands for the flow regime are Re below 2,300 (laminar), 2,300–4,000 (transition) and above 4,000 (turbulent), though actual transition also depends on inlet disturbances, geometry and flow history. There is no solved pump curve, pressure-loss calculation, compressibility or cavitation model, and the vertical loop has no solved gravitational pressure balance. At zero flow, both stress scales vanish and their ratio is mathematically undefined, even though the defining Reynolds equation itself evaluates to zero.
It decreases. At fixed volume flow, mean velocity falls as 1/D² (since Q = V·πD²/4 is held constant), which leaves Reynolds number proportional to 1/D — so a larger pipe at the same flow rate actually reduces Re, the opposite of the fixed-velocity case.
No. They are characteristic stress scales, ρV² and μV/D, each with pressure units — useful for building intuition about the dimensionless Reynolds ratio, but not two independently measured forces read from a physical instrument on this bench.
Velocity and volume flow are related through the pipe's cross-sectional area, so fixing one while changing diameter necessarily changes the other. The console forces this choice explicitly so you see exactly how Reynolds number's dependence on diameter flips depending on which quantity your engineering problem actually holds fixed.
No. Matching Re helps compare the relative influence of viscous and inertial effects for geometrically similar flows, which is the basis of dynamic similarity in scale-model testing, but it does not by itself guarantee every other physical effect — compressibility, free-surface behavior, thermal effects and more — is also matched.