A hybrid approach portraying the dynamics of free convection condensation around a circular cylinder.

This article presents a hybrid modeling framework for analyzing free convection condensation of saturated steam on the exterior of a horizontal circular cylinder. The approach combines an analytical solution for the liquid condensate film, incorporating temperature-dependent thermophysical properties, with a numerical resolution of the adjacent vapor flow field using computational fluid dynamics. Key dimensionless parameters governing the flow are identified as the Jakob number (Ja), Weber number (We), and free-fall Reynolds number (Re_l,FF), with a newly introduced similarity number (SN = We/Ja²) enabling dynamic similarity in the two-phase flow. The study reveals that increasing Ja and We leads to thicker condensate films and higher condensation rates, while surface tension effects influence flow separation points and vapor flow patterns, dividing the vapor domain into entrainment and bypass zones. The model’s predictions align well with existing correlations and provide insights into velocity distributions, pressure gradients, and flow reversal phenomena near the liquid–vapor interface, offering a comprehensive understanding relevant to industrial condensation processes such as steam power generation and refrigeration.