This simulator models water hammer — the pressure surge created when flow in a pipeline is suddenly interrupted — using a one-dimensional frictionless elastic method-of-characteristics calculation. Close a valve at a chosen rate, change pipe length, wave speed, bore, initial velocity and head, and watch the pressure wave launch, travel and reflect along the pipeline in real time.
• A real-time 3D scene of the constant-head reservoir, the elastic pipeline rendered as 40 color-coded pressure cells, the closing valve, three pressure sensors (source, midpipe, valve) and a discharge/flow observation station, 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 (reservoir, pipe, valve, sensors, profile recorder, closure/propagation timing clock, outlet) and click-to-inspect component callouts. • Six experiment controls: pipe length (100–1,000 m), pressure-wave speed (400–1,400 m/s), initial liquid velocity (0.2–2 m/s), initial gauge pressure head (20–100 m), linear valve-area closure time (0.01–5 s) and pipe bore (80–300 mm). • 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 time, initiate valve closure and rearm steady-flow trial actions. • A Curves & measurements tab with a spatial pressure profile across 41 hydraulic nodes, two live charts (station heads and valve velocity), the method-of-characteristics equations (Joukowsky relation, characteristic grid, C+/C− compatibility equations, reservoir and valve boundary conditions) and snapshot measurement readouts. • An Experiments tab with four guided fixtures (rapid closure, slow closure, lower wave speed, steady open valve) 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.
When a valve closes, the fluid column it was passing must decelerate. In a truly rigid, incompressible system this would require infinite force; in reality, the fluid's compressibility and the pipe wall's elasticity let a pressure wave carry that deceleration upstream at a finite speed a (the elastic wave speed), rather than everywhere at once.
The simulator solves this with the method of characteristics on 40 spatial intervals: forward- and backward-traveling characteristic equations (C+ and C−) propagate head and velocity information at speed a, and the reservoir and valve impose fixed boundary conditions — constant head at the reservoir, velocity set by valve opening at the valve. The wave reflects at each boundary, producing the oscillating pressure history you see at the three sensor stations.
The Joukowsky relation, ΔH = a·Δv/g, gives the instantaneous-stop reference pressure rise, and the round-trip time 2L/a tells you how long a disturbance takes to travel down the pipe and back. Comparing your chosen closure time against 2L/a is the key diagnostic: closures much shorter than the round-trip time behave like an instantaneous stop and produce the full Joukowsky surge, while closures spread over several round trips let reflections partially cancel the incoming surge.
This is a one-dimensional, frictionless, horizontal, constant-density model with no air pockets, viscoelastic pipe effects, surge tank or vapor-cavity model — waves persist rather than damping out. If the ideal calculation predicts pressure below 2.34 kPa absolute, the simulator flags the result as invalid rather than silently modeling cavity formation; a real transient analysis would require a full waterhammer/surge study.
Water hammer is the pressure surge (and often audible knock) produced when a moving fluid column is forced to stop or change speed suddenly, such as when a valve closes quickly. The abrupt deceleration launches an elastic pressure wave that travels through the pipeline at the fluid/pipe system's characteristic wave speed and reflects off boundaries like the valve and reservoir.
Closure time compares against the wave round-trip time 2L/a. A rapid closure (much shorter than 2L/a) traps the full instantaneous-stop pressure rise given by the Joukowsky equation, ΔH = a·Δv/g. A slow closure spread over several round trips lets reflected waves partially offset the surge, producing a smaller peak pressure — as the simulator's rapid-closure and slow-closure experiments demonstrate directly.
The model is single-phase and assumes the liquid stays a continuous column. If the calculated ideal pressure drops below the vapor pressure of water (about 2.34 kPa absolute at standard atmosphere), that single-phase assumption breaks down — real fluid could cavitate. Rather than pretending to model cavity growth or collapse, the simulator retains the ideal numbers but sets a validity flag to false.
No. It is a simplified, frictionless, one-dimensional elastic model with no friction damping, air pockets, viscoelasticity, surge protection devices or resolved vapor-cavity dynamics. A real pipeline transient study requires a validated waterhammer/surge analysis accounting for these effects and the specific system geometry.