A theoretical approach to the evaluation of gravity influence on heat and mass transfer in liquids

Abstract

The evaluation of the behaviour of liquids in terms of transport properties has often been carried out trying to adapt well known theories already developed to understand the characteristics of gases and/or solids. Thus, among such theoretical archetypes, a rough distinction can be made introducing the terms “gas-like” and “solid-like” to address models respectively based on an extension of theories originally conceived to study gases and solids. The latter models seem, in general, more reliable and accurate and many efforts have been made to introduce a “convective” term in heat, mass and momentum transfer equations and a new “vibrational” term, as for solids having a strong lattice structure. The presence of such two terms has suggested to study the behaviour of liquids, for what concerns heat and mass transfer, with respect to the presence or not of gravity itself. This paper presents an attempt to assess both the actual contribution of “convective” terms to heat, mass and momentum transfer in liquids and the related effects of gravity.