Permeábilis

Permeábilis is an adjective used in science to describe a material, interface, or medium that allows the passage of fluids or gases. The term denotes a capacity to be penetrated by a substance under certain conditions, and is closely related to permeability. It is used in geology, hydrology, materials science, engineering, and biology, sometimes in a Latinized or Romance-language context.

Permeability depends on pore structure and fluid–solid interactions. Key factors include porosity, pore size distribution, connectivity of the pore network, tortuosity, and chemical compatibility. A permeábilis material may exhibit high or low permeability depending on the fluid, pressure, and temperature. The permeability coefficient k is commonly used to quantify this property, and Darcy's law relates flow rate to k, cross-sectional area, and hydraulic gradient. Permeability can be anisotropic in structured materials.

Examples: sandy soils and fractured rock are typically highly permeábilis to water; clay-rich soils have low permeability. In engineering, permeábilis materials are used for drainage, filtration, and membranes. In biology, membranes are often described as semipermeable or selectively permeable, meaning they allow certain substances to cross while restricting others.

Measurement approaches include constant-head and falling-head tests for liquids, gas permeametry, and porosimetry to relate pore structure to permeability.

See also: permeability, porosity, Darcy's law, selectivity.