The dynamics of bubble coalescence is studied using a robust numerical model for a multiphase flow system with interfaces. The effects of liquid viscosity and surface tension on bubble coalescence, for which Reynolds number ranges from 10 to 100 and Bond number ranges from 5 to 50, are investigated. It is shown that the numerical model used in this study can accurately capture the complex topol...

Understanding the phenomenon of droplet coalescence in nanoparticle suspensions is extremely important for the preparation of Pickering emulsions. A microfluidic platform, which can provide compulsive droplet collisions, was developed to imitate the droplet coalescence process in the early stages of emulsification. Microscope videos showed the variations in the droplet coalescence percentage, d...

Hot tearing: from organic alloys to superalloys. The appearance of solidification cracks or hot tears during casting is a serious defect. EPF-Lausanne has developed a criterion for the appearance of hot tears which is based upon a mass balance performed over the liquid and solid phases and which takes into accounts for the tensile deformation of the solid skeleton perpendicular to the growing d...

The aim of this paper is to review the key findings about how particle-stabilised (or Pickering) emulsions respond to stress and break down. Over the last ten years, new insights have been gained into how particles attached to droplet (and bubble) surfaces alter the destabilisation mechanisms in emulsions. The conditions under which chemical demulsifiers displace, or detach, particles from the ...

Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G*for total energy calculation are reported for Z-cyclooctene (1). The most favorable conformation of 1 is theunsymmetric boat-chair (1-BC) geometry. Potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. The process via a chair transition sta...

The simulation of liquid-liquid extraction columns has been of high interest for the last four decades. The well-known procedure is to solve drop-population balances. This approach reaches its limits if the additional influences like reactions shall be included in the simulation and can be solved only with extremely high mathematical effort. ReDrop (Representative Drops) is an alternative way t...

The coalescence process of oppositely charged drops for different electrical conductivities of liquids is presented. When the electrical conductivity was relatively low, oppositely charged drops failed to coalesce under sufficiently high electrical fields and capillary ripples were formed on the surfaces of droplets after rebound. For a high electrically conductive liquid, it was found that a c...

This paper is an attempt to study the effects of surface topography on flow a droplet (or bubble) in low Reynolds number regime. Multiphase flows through constricted passage find many interesting applications chemistry and biology. The main parameters which determine properties such as rate pressure drop, govern complex multiphase phenomena drop coalescence, break-up snap-off straight channel a...