Porositetta

Porositetta is a measure of the void spaces in a material. It represents the proportion of the material's bulk volume that is empty and potentially occupiable by fluids. Porosity is dimensionless and commonly reported as a percentage or a fraction.

Porosity types: total porosity includes all voids; open or interconnected porosity refers to voids connected to the exterior or to other pores and allows fluid flow; closed porosity consists of isolated voids that do not contribute to fluid storage or transport; effective porosity is the portion of open porosity that contributes to fluid flow under prevailing conditions.

Pore structure influences storage and transport; pore size distribution defines micro-, meso-, macro-pores, affecting capillary rise, permeability, and diffusion. Porosity alone does not determine permeability; a material with high porosity may have low permeability if pores are poorly connected.

Measurement: porosity can be determined by methods such as Archimedes principle (bulk porosity), water saturation (saturation porosity), mercury intrusion porosimetry (pore throat distribution), gas adsorption (nitrogen/argon for micro-pores), and helium pycnometry for skeletal volume. In geology, porosity estimates may come from well logs, core samples, and empirical relationships.

In nature, porosity variants are important in groundwater, hydrocarbon reservoirs, soil fertility, and engineering. Sedimentary rocks like sandstone and limestone vary widely in porosity; clays typically have low porosity but high surface area; coal can have high porosity but limited flow due to low permeability. Engineered porous materials include foams, ceramics, catalysts, and battery electrodes.