# Cavitation Cavitation is boiling caused by falling pressure rather than rising temperature. Where a liquid accelerates — around a propeller tip, through a valve, in the core of a [[Vortex]] — local pressure can drop below the vapour pressure and the liquid flashes to bubbles. Those bubbles then travel into higher pressure and collapse violently. The collapse, not the formation, is what does the damage. ## Collapse is the destructive part A collapsing bubble concentrates the [[Energy]] of a large volume into a very small one, producing a shock and a microjet that can strike a nearby surface at hundreds of metres per second. Repeated a few thousand times a second it pits and erodes even hardened [[Alloy|alloys]] — a well-known [[Fatigue_(material)|fatigue]] and [[Corrosion]] mechanism on pump impellers, ship propellers, and valve seats, and a standard [[Failure_mode_and_effects_analysis]] entry in [[WT!Energy_Center_of_Excellence|hydro]] plants. The collapse is bright and loud enough to register as light and [[Sound]]. ## Designing around it, and using it The guard is net positive suction head: keep the inlet pressure high enough that the liquid never reaches vapour pressure at the impeller eye, which constrains how a [[Water]] pump may be installed. Where cavitation cannot be avoided it is placed deliberately in a sacrificial component. It also has uses — ultrasonic cleaning baths cavitate on purpose to scrub surfaces, and focused [[Ultrasound]] uses controlled cavitation in [[Medicine|clinical]] treatment. Snapping shrimp weaponise it. **Microsim brief (next pass):** Venturi throat with a flow slider and a vapour-pressure line on the pressure trace; bubbles nucleate when the trace dips below it, then collapse downstream with a pit counter on the wall. **On the spine:** [[Two-phase_flow]] · [[Bernoulli's_principle]] · [[Vortex]] · [[Surface_tension]] · [[Reliability_engineering]] · [[WT!Thury_Hydrodynamics_Compendium]]. <!-- SPINEPATH:BEGIN g20 — shortest chain of Wikipedia links between local articles to a Compendium Main article; do not hand-edit inside --> *Connected to the Apex Spine:* Cavitation → [[Fluid_dynamics|Fluid dynamics]] — [[WT!Thury_Hydrodynamics_Compendium|Compendium]] section 1, *Fluid dynamics*. <!-- SPINEPATH:END --> <!-- COMPENDIUMLINK:BEGIN g19 — generated from _registry/plans/THURY_COMPENDIUM_SECTIONS.md; do not hand-edit inside --> **Part of the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]]** — main article for section 29, *Cavitation*. Related sections: [[Hydropower]] · [[Hydroelectricity]] · [[Boundary_layer]]. <!-- COMPENDIUMLINK:END --> <!-- THURYSIM:BEGIN g21 — Thury Compendium microsim (framework build, specs/sims/Cavitation.json); do not hand-edit inside --> **Microsim — three.js (Wikitube framework):** *Cavitation* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/thury/Cavitation.html" data-title="Cavitation"></div> *Built from `MICROSIM_GUIDE/specs/sims/Cavitation.json`; part of the [[WT!Thury_Hydrodynamics_Compendium|Thury Hydrodynamics Compendium]] set.* <!-- THURYSIM:END --> ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Cavitation) : [Wikitube](https://en.wikitube.io/wiki/Cavitation) ## Previous hub tags Hubs: `Life_Physics`, `Systems`. Portals: [[PORTAL_WT!Thury_Hydrodynamics_Compendium]], [[PORTAL_Physics]], [[PORTAL_Reliability_engineering]]. --- *Fluid seed wave · 2026-09-10 · seed register · microsim layer pending.*