CFD modeling of free surface flow with and without condensation

This paper presents some recent developments on CFD models suitable to simulate free surface flows, which so far have represented an unresolved matter for industrial nuclear reactors issues. While the general dynamics of such a large interface should be simulated in a CFD approach, all subgrid scale effects have to be modeled. Depending on choice of the general approach, i.e., one-fluid or multifluid models, different closures are required. The momentum transfer between the phases is usually reflected by a drag model in a two-fluid approach. The drag force depends on the local morphology (free surface or dispersed bubbles/drops) and has to be anisotropic at the free surface. Surface tension has to be considered at wavy surfaces. The situation becomes even more complex if mass transfer occurs at the interface. Three approaches with different detailedness are presented. Examples for CFD simulations for free surface flow using different CFD codes and approaches are discussed. © 2011 by Begell House, Inc