Numerische Untersuchung des Tropfenverhaltens an Hindernisgeometrien unter Einfluss von äußeren Kräf

Multiphase flows play an important role in many technical applications, for example in the areas of sensor technology and process engineering. Indeed, for certain two-phase flows an extensive knowledge of the dynamic behavior of liquid droplets in gas flows is essential in order to ensure the correct functionality of the fundamental processes. In general, flow conditions, interface properties as well as the wetting behavior determine the dynamics of a droplet. The complexity of the examined problem increases, if obstacle geometries, superpositions of external forces or various fluid properties are considered. Such complex flow processes can be efficiently examined in detail by means of the numerical flow simulation.In the present work, the results of a numerical investigation concerning the droplet behavior due to external forces and interactions with a wall-mounted obstacle are presented. Thereby, a wide range of droplet properties, two different surfaces, external effects such as the gravitation, the gas flow, vibrational excitations or superpositions of various forces as well as differe obstacle heights are considered.First, an already existent numerical implementation of the contact angle hysteresis was further developed with regard to its universal applicability. The optimized numerical method was then validated on the basis of available experimental results and allowed to gain new insights into the dynamic behavior of droplets. Considering the droplet deformation and breakup due to the interaction with a wall-bounded obstacle with a rectangular cross-section, an empirical dimensionless representation was derived, which allows the categorization and prediction of the occurring droplet phenomena as a function of the process parameters.