Abstract
A three-dimensional two-fluid model for two-phase flow within tube or rod bundles is presented. The porous media concept is applied in the model statement. Closure laws for interfacial mass, momentum and energy transfer, bundle flow resistance and heat transfer are presented. Correlations for the interfacial drag force are proposed. Some illustrative examples of application (including also verification) to two-phase flows in complex geometries and across vertical and horizontal tube/rod bundles are presented below. The developed model is suitable for the simulation and analyses of complex multidimensional thermal-hydraulics of nuclear fuel rod bundles or shell-and-tube heat exchangers with vapor generation within a tube bundle on the shell side.