Modelling and numerical methods for nanoparticles in a gas phase

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The proposed project aims at the modeling and simulation of dynamical phenomena related to nanoparticles in a gas phase. It has a special relevance for processes of gas-phase synthesis of nanoparticles. One focus of the project will be on thermophoresis of particles and orientation effects occurring when these particles are deposited on a cold surface. Another important objective is a better understanding of the gas-kinetic interaction forces between particles that exchange mass with the gas. The resulting forces may support or prevent particle agglomeration. The models employed will include effects of temperature gradients, Brownian particle dynamics, and condensation/eva-poration/sublimation of molecules at the particle surface. As a special case, also droplets and their internal flow patterns will be modeled. On the one hand, (semi)analytical models will be employed to better understand some key processes related to gas-phase dynamics of nanoparticles. These models will rely on a number of simplifications compared to the full scenario. Detailed numerical simulations of nanoparticles in a gas will be the second pillar. For that purpose an existing Monte-Carlo simulator will be extended to account for particles with heterogeneous surfaces and phase change. In addition, for the simulation of droplets in a rarefied gas the Monte-Carlo code will be coupled to a Navier-Stokes solver.