doi:10.1016/j.ijthermalsci.2026.110845engCollado, Francisco J.Void fraction profile for subcooled flow boiling through reversing saturationART-2026-148929This work is a continuation of a previous one (F.J. Collado, Phys. Fluids 34, 2022, 123302) where a new model of vapor void fraction was compared against some tests of the void axial profile for upward subcooled flow boiling of water reported by MPI in the eighties. The new void model was based on a new energy balance where heat was divided by the mean vapor-liquid velocity ratio, or slip ratio. The model tried to predict the slip ratio profile, next the mixture enthalpy could be derived from the new heat balance and finally the void fraction was obtained. The mixture enthalpy was based on the classic thermodynamic quality, which includes the void fraction. The slip ratio profile model proposed was dependent on five unknown parameters, although only two new thermo-kinematic equations were suggested then solving two parameters. In this work, the new slip ratio profile model has been simplified to just three parameters and, correspondingly, three new equations have been proposed. First, the continuity of the first derivative of the mixture velocity but here modified by the new slip function. Second, a new equation resulting of the theoretical equilibrium liquid velocity intercept with the reversing vapor velocity from saturation. And third, a new procedure for searching the best location of the onset of nucleate boiling (ONB), which is based on minimizing the absolute error, is suggested. Moreover, thermal approximations to the best ONB found are explored. This simplified void model is favorably checked against the full set (twenty-four) of void fraction profile MPI tests.2026http://zaguan.unizar.es/record/17044510.1016/j.ijthermalsci.2026.110845http://zaguan.unizar.es/record/170445oai:zaguan.unizar.es:170445INTERNATIONAL JOURNAL OF THERMAL SCIENCES 226 (2026), 110845 [22 pp.]by-nc-ndhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.esinfo:eu-repo/semantics/openAccess