Closure conditions for computation of thermal nonequilibrium in two-phase flows

Computational systems for describing multiphase process and system behavior must have constitutive relations which adequately describe physical processes. It is shown that nonequilibrium phase change for steady flow is an initial value, history dependent process which requires an accurate description of both the quantity of interfacial area and the interfacial heat transfer for proper description. In addition, proper selection of the initial condition for onset of nonequilibrium must be specified if the resultant constitutive relations are to prove accurate. Examples are given of application to both post-dryout heat transfer and flashing of initially subcooled fluids. (author)