Lubricated viscous gravity currents of power-law fluids. Part 1. Self-similar flow regimes

We examine the gravity-driven flow of thin films viscous fluid power-law rheology, lubricated by another from below. Such flows are relevant to a range geophysical and industrial settings, including ice sheets fast-flowing streams below layer subglacial till. model both layers using lubrication theory in two-dimensional axisymmetric limit which vertical shear provides dominant resistance flow. The is self-similar if exponents, describing rheology two fluid, equal. similarity solutions geometries describe terms four distinct regimes ranging coating more above, lubricating In contrast former scenario, film low-viscosity strikingly alters dynamics when it lubricates below: overlying thins, upper surface gradients lessen most confined lower layer. features amplify, this regime becomes increasingly fluids thinning, like deformation glacial on large scale. This sheets, accelerate, forming streams, they well