Direct Numerical Simulation of Film Flows on Microstructured Surfaces with absorption of a gas phase

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Structured high-performance packing, as found for example in packed columns, and falling film evaporators can have microstructures on the overflown surfaces with geometrical dimensions in the same order of magnitude as the thicknesses of liquid trickle films (< 1 mm). The characterization of the mass transport coupled with the fluid dynamics in the liquid trickle film is very important for the precise description of these multiphase process engineering apparatuses. Since the experimental analysis of the flow over and around the various surface structures, particularly without further influencing the flow, is very involved and complex, the reasons for the dependence are insufficiently researched. During the first project phase the influence of the microstructures on the hydrodynamik was successfully researched. Based on that the aim of this research project is therefore the systematic investigation of the influence of individual and periodically arranged microstructures on the hydrodynamics of liquid film flow and absorption of a gaseous component using Direct Numerical Simulation. In doing so, fundamental research to answer the question How do microstructures influence the mass transport in film flows? will be undertaken. For the simulations, the complete Navier-Stokes equations and no further simplified models for turbulent flows as well as momentum and mass transport between the phases are used. Through the resolution of all occurring length and time scales the cross-mixing in the film and the dynamics of the interfacial surface can be observed very closely and the influence of various microstructures on the mass transfer can be systematically investigated. The simulations are expected to deepen the basic understanding of the influence of the microstructures on the flow and the mass transport. Moreover, these fundamental investigations can elucidate the semi-empirical equations for the dimensioning of columns and extend the scientific knowledge to, for example, give details on the design of novel surfaces.