CFD based investigation of the dynamics, stability and transition regimes of gravity driven rivulets and other constrained liquid surfaces.

The project envisages an experimental and CFD investigation of the stability of thin films of liquid flowing down inclined solid surfaces. Such flows frequently display a plethora of regimes as the flow rate is increased (meandering, braiding and many more) and knowledge of these leads to improved mass and heat transfer predictions in many industrial applications [1]. The stability of such flows sensitively depends on the wettability of the solid surface by the liquid. In this project, the student will build upon work by an existing Ph.D. student in the lab. The research will involve extensive experiments and CFD based simulations of two phase flows using the open source codes Gerris/Basilisk. An in-house developed Navier-Stokes solver for simulating two phase flows also exists and can be used by the student. An experimental setup exists in the lab and will be employed immediately. The work will later expand into stability of constrained liquid surfaces (rivulets are special cases of these). Recent research has shown that a ``periodic table" of motion of such constrained surfaces can be constructed.

Bibliography:

1. On the stability of rivulet flow, J. Fluid Mech. 1990, Schmuki and Laso.

2. Droplet motions fill a periodic table, PNAS, Steen, Chang and Bostwick, 2019.