Hydrothermal Eruption Jets: Air Entrainment and Cooling

Abstract

This paper proposes a quantitative model for the "fountain" of boiling water and rock particles ejected from a hydrothermal eruption. The model is based on principles of conservation of mass, momentum and energy. The main volumetric constituent is steam, which is diluted by entrained air as the jet rises. It is proposed that small rock particles and water droplets (from condensed steam) are carried up by the column while their weights are exceeded by the lift force of the rising gas mixture. They then exit from the column to be deposited. This paper primarily examines the form of the eruption jet when constrained by the conservation principles' requirements. A typical example is used to illustrate the model; calculated column shapes, fluid speed, phase compositions and particle exit heights are depicted and are discussed.