April 4, 2019
Stevin room b.044
Evaporation: from engineering models to kinetic theory
By Bruno Dias (Von Karman Institute)
Evaporation is a phenomenon which is present in our daily life. The industrial and research applications are vast and yet engineering models are not predictive for several problems. The evaporation problem is also an essential phenomenon for studying the entry of meteoroids into Earth’s atmosphere. Accurate models will help the planetary science and astrophysics community to understand better the mass deposition of essential elements such as alkali metals into the upper atmosphere.
This phenomenon is characterized by a non-equilibrium region (Knudsen layer) in front of the surface of the order of several mean free paths that cannot be solved by the continuum approach. Ytrehus et al.  derived general jump conditions, such as density and temperature, across the Knudsen layer for a simple mixture by using moment methods which agree with the numerical solution (DSMC) of Boltzmann equation .
The objective of this talk is to present the different models existing for the evaporation problem and to show the effects of extending the model proposed by Ytrehus to more complex mixtures. The current results were also compared with DSMC results.
 Ytrehus, T. ; Otmo, S. Kinetic theory approach to interphase processes
International Journal of Multiphase Flow, 1996, 22, 133 - 155
 Frezzotti, A.; Gibelli, L. & Lorenzani, S. Mean field kinetic theory description of evaporation of a fluid into vacuum Physics of Fluids, 2005, 17, 012102