Abstract
The constitutive relation between the viscosity, temperature and hydrostatic pressure of liquid materials is investigated by the inelastic deformation theory (combined mechanism model) proposed in the previous paper in order to explain the inelastic behavior of solid materials. The constitutive relation of water and some other liquid materials is well explained quantitatively by the theory. The following are obtained : liquid flow due to several mechanisms, which are thermal activation processes similar to those of solid materials; the liquid region in a pressure-temperature diagram divided into several (mainly three) subregions classified by flow mechanism; a proposed constitutive equation containing hydrostatic pressure.
