Grzegorz Gruszczyński, ZA MEiL, Modelling of immiscible multiphase flows over Super Hydrophobic Surfaces using phase-field, Cascaded Lattice Boltzmann Method.

The lattice Boltzmann method, thanks to its mesoscopic nature is a suitable candidate to simulate the intermolecular interactions responsible for the interfacial flows in a microscale. Additionally, the LBM is relatively easy in implementation and able to handle complex geometries such as porous media or rough surface. Computations are performed locally, thus the algorithm can be parallelized in a straightforward manner.  In this contribution, we present a conservative, phase-field model for simulation of immiscible multiphase flows using an incompressible, velocity based Cascaded Lattice Boltzmann Method (CLBM). We introduce improvements to the LB equations for interface tracking and incompressible hydrodynamics, by transforming the operations to the reference frame which is moving with the fluid. As a consequence, CLBM enhances Galilean invariance and stability of the method. As a study case, we will consider a flow over a Super Hydrophobic Surface (SHS). Generally, the ability of SHS to reduce drag, maintain dry and clean comes from both chemical interactions and shape of the
surface in a microscale. The principle of work is based on the fact, that tiny air-bubbles are entrapped into the microstructure of the surface being in the contact with fluids which is  sliding over them. Unfortunately, usage of SHS depends on the flow condition. It may happen, that too fast flow or improper shape of the surface would cause the air-bubbles to wash out  and to loose the desired properties. Application of LBM to simulation of the SHS is a recent research field in this method.

Keywords:
Cascaded Lattice Boltzmann Method, phase-field, multiphase flows, Super
Hydrophobic Surfaces