Water enters through a service meter and isolation valve, crosses a shared main and climbs a vertical riser that feeds five fixture branches with faucets and basins. Change service pressure, how many fixtures are open (starting at the lowest floor), shared-main diameter and branch conductance, and read pressure and flow at each point.
• A real-time 3D view with numbered, clickable parts: service meter and isolation valve; vertical supply riser; fixture branch connections; faucets and basins; pressure and flow instruments. Scene tools include home view, focus-selected-part, auto-rotate, expand and show/hide labels, and drag-to-orbit with pinch-to-zoom. • Experiment controls: service pressure (100–600 kPa gauge); open fixtures, starting at lowest floor (0–5); shared main diameter (15–40 mm); branch conductance multiplier (0.1–1), plus a show flow/process markers toggle, pause/resume, single-step buttons (0.1 s and 1 s), a playback-speed selector and a restart experiment action. • Live readouts: total delivered flow; riser-base pressure; shared-main pressure loss; top branch available pressure; top fixture flow; pressure-balance residual. A model response curve is drawn beside the 3D view and updates as you change controls. • A Curves & measurements tab with two live charts, the model equations as written in the simulator and snapshot readouts; an Experiments tab with 3 guided presets (all outlets closed; constrict the shared main; close upper outlets) plus a model-verification bench, timestamped event log and copyable trial report. • A Learn & assess tab with 3 lessons (follow the system; connect the measurements; interpret the model), a 2-question knowledge check with reset, and a written model-scope statement.
Every open fixture draws through the same main, so total flow produces a pressure loss that grows with the square of flow: Kmain is scaled as 0.025 (25/d)^5, making a narrower main much more restrictive. The riser-base pressure is service pressure minus that loss, and each branch then loses 9.80665 kPa per meter of elevation.
Flow at each open branch depends on the pressure available there, so the top fixtures lose the most. As you open more fixtures, total demand rises, the main loss grows and every branch sees less pressure.
The simulator lists a pressure-balance residual that should stay near zero, confirming that the numerical solution is consistent. Closing all outlets makes flow and main friction loss zero while the elevation pressure differences remain, and constricting the main lowers both delivered flow and pressure.
The model is a steady incompressible network with one common quadratic resistance and pressure-dependent outlets. It has no transients, simultaneous-demand standards or water-quality calculations, and dimensions are enlarged for explanation. It is a generic educational model, not a code-compliance check or sizing tool.
All open fixtures draw through the same shared main, and friction loss rises with the square of total flow, so the pressure left at the riser base falls for everyone.
Each meter of elevation costs about 9.81 kPa. After the riser-base pressure is set, higher branches have that much less pressure available.
It raises the common resistance steeply, since the model scales it with the fifth power of diameter. Total flow drops and branch pressures fall.
No. It is a generic teaching model with specified resistances and no simultaneous-demand rules. Use the adopted plumbing code and a qualified designer for real sizing.