Numerical two-phase flows study in channels with variable cross-section.

Bubbles and drops dynamics through capillaries of variable cross-section still remains of considerable importance in two-phase flows. The aim of this work is to investigate two-phase flows found in the cooling of new generation of computer processor units in the scope of the ThermaSMART - Marie-Curie/RISE Consortium. We seek to study numerically the effects of domain boundaries to the bubble dynamics, including change in the film thickness, bubble shape and vortex shedding in channels with variable cross-section using a moving mesh/boundary domain scheme, which dramatically shortens the domain length. Such a scheme moves the computational boundary nodes according to the bubble's center of mass relative to the variable cross-section of a given problem. The new methodology proposed to simulate two-phase flows in variable cross-sectioned channels shows good accuracy to describe interface forces and bubble dynamics in different complex geometries with moving boundaries.