This simulator models pressure distribution in a still liquid column with a regulated headspace, a traversing pressure probe and a submerged test strip. Adjust liquid depth, density, headspace gauge pressure, probe position and strip width, and separate gauge pressure from absolute pressure while watching the resultant force on the submerged strip move.
• A real-time 3D cutaway workbench of the still-liquid pressure vessel, a regulated headspace with a vent, a traversing pressure probe, a probe transducer and pressure dial, a submerged test strip with a resultant-force marker, pressure-distribution arrows and a depth-datum/force console, with home view, focus-selected-part, full-enclosure toggle, exploded view, auto-rotate, expand and show/hide labels controls. • Five laboratory controls: liquid depth (0.3–4 m), liquid density (600–1300 kg/m³), headspace gauge pressure (0–100 kPa), probe depth below surface (0–100% of liquid depth) and submerged strip width (0.2–1 m). • Playback controls: pause/resume, 0.1 s and 1 s step advances, four speeds, plus a 'Vent headspace to atmosphere' quick action. • A Curves & measurements tab with a gauge/absolute-pressure chart, a net-strip-force chart, a pressure/flow history chart, the full equation set (pg(z) = pgas,g + ρgz, absolute pressure, strip force integral, center-of-pressure depth) and snapshot readouts. • An Experiments tab with four guided fixtures (water column at atmosphere, probe at the surface, pressurized headspace, denser liquid) and a Model verification bench with an independent-check run, timestamped event log and copyable trial report. • A Learn & assess tab with guided lessons, a knowledge-check quiz with reset, and a written model-scope statement with a reference link.
Hydrostatic pressure grows linearly with depth below the free surface: pg(z) = pgas,g + ρgz, where pgas,g is the headspace gauge pressure. Absolute pressure adds the atmospheric reference, pabs = 101.325 kPa + pg — so venting a vessel to atmosphere (zero gauge pressure) does not make absolute pressure zero, it simply returns it to atmospheric, as the 'Probe at the surface' experiment shows directly.
In the default 'Water column at atmosphere' experiment, a probe at 1 m depth reads 9.80665 kPa gauge and 111.13165 kPa absolute — demonstrating both the ρgz relation and the absolute-pressure offset in a single readout.
Because pressure increases with depth, the resultant force on the submerged test strip acts below the strip's geometric centroid — the deeper portion of the strip is weighted more heavily in the force integral. Adding headspace gauge pressure (the 'Pressurized headspace' experiment) adds a uniform 80 kPa to every depth, which does not change the pressure gradient but does move the resultant closer to the centroid, since the added uniform term reduces the relative influence of the depth-varying part.
This is a static, uniform-density, incompressible-liquid model at g = 9.80665 m/s² with a regulated gas boundary — it excludes gas compression, vessel stress, sloshing, compressibility and thermal effects, and every parameter change establishes a new equilibrium instantly rather than modeling a transient.
Gauge pressure is measured relative to atmospheric pressure (101.325 kPa), while absolute pressure includes that atmospheric reference. The simulator shows both: at the default 1 m water depth, gauge pressure is 9.80665 kPa while absolute pressure is 111.13165 kPa.
No. Venting returns gauge pressure to zero, but absolute pressure returns to the atmospheric reference of 101.325 kPa, not zero. The "Probe at the surface" experiment with the default vented headspace demonstrates this directly.
Because hydrostatic pressure increases with depth, the deeper part of the strip experiences higher pressure and contributes more to the force integral, pulling the resultant below the geometric centroid. Adding uniform headspace pressure shifts the resultant back toward the centroid.
Yes. Pressure increase per metre of depth is ρg, so the "Denser liquid" experiment (1200 kg/m³ versus water at 1000 kg/m³) increases the hydrostatic pressure gradient by 20% at the same depth and headspace pressure.