Multiphase CFD-Simulation of Transport Phenomena in Sewer Systems

This paper presents different computational fluid dynamics applications using the multiphase solver interFoam which is implemented in the open source software OpenFOAM. The solver uses the volume of fluid approach. When modelling tracer transport in the proximity of the interface between two phases, the problem of non-physical tracer spreading across the interface has to be overcome. In this paper, two ways are presented to model such systems successfully. First, tracer transport around concrete probes in the headspace of a sewer pilot plant is considered. In this case a two-phase (water-air) system is assumed by describing an idealized water surface as a boundary condition and a passive tracer is applied. Second, flow in a complex sewer stretch containing a hydraulic jump is simulated and a tracer is applied in the water phase. A multiphase transport approach based on the Henry coefficient is used in this case and plausible results are obtained.