Numerical Study of Droplet Motion in a Hydrophilic/Hydrophobic Microchannel

The droplet dynamics in a hydrophilic/hydrophobic microchannel, which is applicable to a typical proton exchange membrane fuel cell (PEMFC), is studied numerically by solving the equations governing the conservation of mass and momentum. The liquid-gas interface or droplet shape is determined by a level set method which is modified to treat the contact angles. The matching conditions at the interface are accurately imposed by incorporating the ghost fluid approach based on a sharp-interface representation. Based on the numerical results, the droplet dynamics including the sliding and detachment of droplets is found to depend significantly on the contact angle. The effects of inlet flow velocity, droplet size and side wall on the droplet motion are quantified. Also, a droplet removal process is demonstrated on the combination of hydrophilic and hydrophobic surfaces.