Numerical investigation of flow film condensation over an inline arrangement of two cylinders in the combined natural and forced convection regime

The problem of flow film condensation over an inline arrangement of two cylinders is studied using threedimensional numerical simulations. The interface evolution, the flow, and the heat transfer characteristics have been investigated using varying flow and geometrical parameters. The condensate removal from the top cylinder is mostly in the form of individual droplets. However, a liquid column develops between the cylinders as the condensate from the top cylinder is drained to the bottom cylinder. The number of droplet formation sites increases considerably as the cylinder diameter increases. As the cylinder diameter is decreased, the interface evolution pattern between the cylinder changes from individual droplets to a combination of liquid sheets and droplets. Furthermore, the condensate removal pattern from the top cylinder to the bottom cylinder changes from a combination of droplets and liquid columns to stable liquid columns as the wall subcooling increases. Additionally, the effect of different parameters on film condensation is also assessed in terms of the different quantitative results, such as the dimensionless liquid film thickness, dimensionless departure diameter of liquid droplets, dimensionless location of the breakup point of the liquid column between the two cylinders and the space-time-averaged Nusselt number.