Stability of thermocapillary flows with inclined temperature gradient

The stability of a two-layer return thermocapillary flow in the presence of an inclined temperature gradient is investigated. Both a linear stability analysis and nonlinear simulations have been performed for an air-water sys tem. It is found that a rather weak deviation of the mean temperature gradi ent from the vertical direction suppresses Pearson's instability mechanism and leads to the appearance of oblique hydrothermal waves. In a certain reg ion of parameters, transverse convective rolls drifting with the mean flow appear.