How do cavities form
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Understanding the Formation of Cavities
Cavities, or voids, can form in various contexts, from biological systems to physical environments. This article synthesizes research findings on the mechanisms behind cavity formation across different domains, including fluid dynamics, biological tissues, and geological formations.
Cavity Formation in Fluid Dynamics
Spheres Entering Stratified Liquids
When rigid spheres submerge into a stratified two-layer system of immiscible liquids, such as a thin oil layer above water, unique cavity dynamics are observed. The oil coating on the spheres significantly affects the cavity formation, leading to ripple-like patterns on the cavity walls due to shear instability between the oil and water layers1.
Partial Cavities on Hydrofoils and Wedges
Partial cavities can form on the vertices of wedges and the leading edges of hydrofoils. These cavities exhibit different behaviors based on their geometry. Open partial cavities terminate near the point of maximum thickness, shedding vapor-filled vortices in the turbulent wake. In contrast, closed cavities form re-entrant jets that direct flow upstream, leading to periodic cloud cavitation2 3.
Surface Condition Effects
The surface condition of spheres entering water also influences cavity formation. Contaminated spheres form cavities at lower entry speeds compared to clean ones, indicating that surface contaminants and viscosity play a role in the dynamics of cavity formation10.
Biological Cavity Formation
Tuberculous Cavitation in Lungs
In pulmonary tuberculosis, cavities form in lung tissue due to mechanical stress on necrotic granulomas. These cavities often develop rapidly from areas of consolidation and are associated with high mechanical stress, leading to acute tears in weakened tissue and subsequent air trapping4.
Tree Cavities in Forest Ecosystems
Tree cavities, essential for many animal species, form primarily through fungal decay and mechanical damage. In tropical and temperate forests, cavities are more common in larger and dead trees. The orientation and density of these cavities vary with environmental factors such as elevation and tree species5 7.
Geological Cavity Formation
Permafrost Cavities
In ice-rich permafrost, cavities can develop following significant rainstorms and runoff events. These cavities form along permeable zones in sediments with ice lenses, promoting subsurface flow and ground surface collapse. Stability of these cavities depends on drainage and the surrounding frozen ground's rigidity6.
Conclusion
Cavity formation is a complex process influenced by various factors, including fluid dynamics, biological tissue properties, and geological conditions. Understanding these mechanisms provides insights into the behavior of cavities in different environments, from the microscopic scale in biological tissues to large-scale geological formations.
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Most relevant research papers on this topic
Cavity formation in the wake of falling spheres submerging into a stratified two-layer system of immiscible liquids
Cavity formation in the wake of rigid spheres submerging into a stratified two-layer system of immiscible liquids leads to a unique ripple-like pattern on cavity walls, influenced by the oil coating and the ambient water.
Partial cavity flows. Part 1. Cavities forming on models without spanwise variation
Partial cavities can form on two-dimensional wedges and hydrofoils, with open cavities causing large-scale condensation and unsteady re-entrant cavities causing cloud cavitation and laminar flow reattachment.
Highly CitedPartial cavity flows. Part 2. Cavities forming on test objects with spanwise variation
Partial cavitation forms on three-dimensional test objects, with closed cavities and re-entrant jets forming, resulting in steady, laminar flow reattachment and largely irrotational flow around the closed cavity.
Highly CitedDiverse Cavity Types and Evidence that Mechanical Action on the Necrotic Granuloma Drives Tuberculous Cavitation.
Tuberculous cavitation is driven by mechanical stress on necrotic granulomas, leading to acute tears in structurally weakened tissue, followed by air trapping and cavity expansion.
Non-RCT
Animal StudyDensity and characteristics of tree cavities inside and outside Volcanoes National Park, Rwanda
Large and dead trees of specific species are important cavity substrates in Volcanoes National Park, Rwanda, with cavity density declining with elevation.
Observational Study
Rigorous JournalCavity development in ice‐rich permafrost, Pangnirtung, Baffin Island, northwest territories
Seasonal temperature changes are key factors in destabilizing near-surface cavities in ice-rich permafrost, following large rainstorms and runoff events in 1984.
Density, Distribution, and Attributes of Tree Cavities in an Old‐Growth Tropical Rain Forest
Cavities in tropical forests are common and often formed by damage or decay, contrary to predictions, and may increase from poles to the tropics.
Formation of aerenchyma in roots of Zea mays in aerated solutions, and its relation to nutrient supply
Inadequate nitrogen supply in maize roots leads to deterioration of cortex cells and cavity formation, suggesting reduced nitrogen assimilation.
Highly CitedReal-time microscopic and rheometric observations of strain-driven cavitation instability underlying micro-crack formation in asphalt binders
Strain-driven cavitation instability in asphalt binders leads to micro-crack formation, with the presence and material properties of microstructural entities influencing damage nucleation.
Effect of Surface Condition of a Sphere on Its Water‐Entry Cavity
Cavities form at lower entry speeds for contaminated spheres than clean ones, with little dependence on the type of contaminant, size, or specific gravity of the sphere.
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