A hybrid Navier-Stokes/DSMC simulation for rarefied gas flow for the deposition of nano layers for OLEDs

Flows of gas through nozzles with abrupt changes in cross-sectional area are often encountered in practice. In our case such nozzles are used as short length diffuser for producing a layer of organic light-emitting diodes. A hybrid Navier- Stokes/Direct Simulation Monte Carlo simulation is necessary here due to the strong decrease in pressure in the system related to an increase in the Knudsen number. Two popular software tools were coupled. For the domain, where the continuum theory is valid, ANSYS Fluent was chosen, which is one of the world wide leading simulation software for Navier-Stokes simulations. The open source CFD toolbox OpenFOAM includes a widely used Direct Simulation Monte Carlo (DSMC) solver. We coupled both solvers doing a one-shot NS-simulation in the whole domain and defined the boundary to the DSMC subdomain manually. Data are exchanged using Dirichlet-Dirichlet type boundary conditions. Our implementation was validated by comparing the results with two experiments. In this paper we d...