Water hammer and hydraulic transient simulation

Water hammer is a pressure surge that travels through a pressurized pipe when flow changes suddenly — for example when a valve closes, a pump trips, or a pipe bursts. The same physics is often called a hydraulic transient or pipeline transient. Rapid events can raise or drop pressure enough to damage pipes, collapse linings, or contaminate a water distribution network.

Engineers study these events with transient simulation rather than steady-state EPANET alone. Steady models assume demands and flows have already settled. A water hammer calculator has to step through time and track pressure waves.

Method of Characteristics (MOC)

TSNet-TS uses the Method of Characteristics, a standard numerical scheme for unsteady pipe flow. It discretizes each pipe so that pressure and velocity are updated along characteristic lines at a time step limited by wavespeed and pipe length. That is the same family of methods used in research codes such as TSNet (Python).

EPANET networks in the browser

Upload an EPANET .inp model or try a built-in example. Simulation runs locally in your browser: valve closure, pump trip, pipe burst, leak, demand pulse, and surge tank protection. Steady-state initialization can be demand-driven (DD) or pressure-dependent (PDD).

Open the online transient simulator

When to run a transient model

• Valve closure or opening that is fast compared with the pipe period 2L/a
• Pump shutdown or startup and the resulting downsurge or upsurge
• Pipe burst or background leak where pressure-dependent outflow matters
• Checking whether a surge tank reduces water-hammer peaks

FAQ

What is water hammer?

Water hammer is a pressure surge in a pressurized pipeline when flow changes suddenly, such as a fast valve closure, pump trip, or pipe burst. It is a type of hydraulic transient.

Can I run water transient simulation in the browser?

Yes. TSNet-TS runs Method of Characteristics (MOC) transient simulation in your browser. Upload an EPANET .inp file or try an example network — no server-side solver is required for the demo.

Does TSNet-TS support EPANET .inp files?

Yes. TSNet-TS loads EPANET water distribution network models (.inp) and simulates valve closure, pump trip, pipe burst, leaks, demand pulse, and surge tanks.

What is the difference between DD and PDD?

DD (demand-driven) assumes junctions take their full assigned demand. PDD (pressure-dependent demand) reduces demand when pressure is low, which is more realistic for leaks and bursts. Both use EPANET for the steady-state start.

Is TSNet-TS free?

The online demo is free for noncommercial use. The TypeScript engine is published as @tsnet-ts/ts-net on npm under the MIT license.