Abstracts - KTH Mechanics

28
Mesoscopic Modelling of atwo phase flow in presence of the
boundaries
M. Sbragaglia ∗ ,L. Biferale † ,R. Benzi † and S.Succi ‡
We present a mesoscopic model, based on the Lattice Boltzmann Equations 1 ,for
the interaction between a solid wall and a non-ideal fluid. We study the dependency
of the wetting properties on the free parameters of the model, i.e. the equivalent of
the wall density and of the wall-fluid potential in Molecular Dynamics studies. We
compare our model with some exact results based on the Navier-Stokes equations
for a single-phase fluid with suitable boundary conditions 23 . Finally, the onset of
dewetting transitions 4 on micro-corrugated surfaces is investigated.
The robustness of this approach over a wide range of scales, makes it a suitable tool
to investigate various boundary condition problems including capillary effects coupled
to rough surfaces and non-slip boundary conditions.
∗ Department of Applied Physics, University of Twente, 7500 AE Enschede, The Netherlands
† Department of Physics, University of Rome ’Tor Vergata’, I-00133 Rome, Italy
‡ Istituto per le applicazioni del calcolo CNR-IAC, I-00161 Rome, Italy
1 Chen et al., Annu. Rev. Fluid. Mech. 30, 329 (1998)
2 Lauga et al, J. Fluid. Mech. 489, 55 (2003)
3 Philip, Z. Angew. Math. Phys. 23, 353 (1972)
4 Cottin-Bizonne et al. Nature Materials 2, 237 (2003)
Figure 1: Onset of dewetting transitions in a Lattice Boltzmann Model. The critical
interplay between a rough surface (black) and surface tension effects produce a
dewetted state with gas pockets (white) on which the liquid (red) can slide producing
enhancement of the effective slip properties.