Although Italian by birth, maritime explorer Christopher Columbus sailed across the Atlantic Ocean and discovered the Americas under the Spanish emperorâs name. During his first voyage, he led three Spanish galleons, the NiÃ±a, Pinta, and the Santa Maria.
Instead of the general notion that a void is a region of space with a low cosmic mean density; a hole in the distribution of galaxies, it defines voids to be regions in which matter is escaping; which corresponds to the Dark Energy equation of state, w.
In gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase.