Wetting films in thermal gradients

Previous experiments revealed some unusual behavior of wetting films driven across inclined surfaces by thermal gradients. Below a certain threshold f ilm thickness, the film, predictably, formed a bump that was stationary but subject to a fingering instability. Above the threshold the bump was, unex pectably, stable but nonstationary. This new structure was identified by Be rtozzi, Munch, and Shearer as that of an undercompressive shock. In this st udy we investigated the extent to which their proposed model, dealing with infinite films spreading across infinite, ideal substrates, can be applied to real systems of finite dimensions. It was found that while the velocity and width of the bump were not subject to finite size effects, the profile of the bump was not accurately predicted by the model.