Twodimensional similarity solutions for finitemass granular avalanches with Coulomb and viscoustype frictional resistanceK. HUTTER and R. GREVE AbstractThis paper is concerned with the motion of an unconfined finite mass of granular material down an inclined plane when released from a rest position in the shape of a circular or elliptical paraboloid. The granular mass is treated as a frictional Coulomblike continuum with a constant angle of internal friction. The basal friction force is assumed to be composed of a Coulombtype component with a bedfriction angle that is positiondependent and a viscous Voellmytype resistive stress that is proportional to the velocity squared. The model equations are those of Hutter and others (in press b) and form a spatially twodimensional set for the evolution of the avalanche height and the depthaveraged inplane velocity components; they hold for a motion of a granular mass along a plane surface. Similarity solutions, i.e., solutions which preserve the shape and the structure of the velocity field, are constructed by decomposing the motion into that of the centre of mass and the deformation relative to it. This decomposition is possible provided the effect of the Voellmy drag on the deformation is ignored. With it, the depth and velocities relative to those of the centre of mass of the moving pile can be determined analytically. It is shown that the pile has a parabolic cap shape and contour lines are elliptical. The semiaxes and the position and velocity of the center of mass are calculated numerically. We explicitly show that
Journal of Glaciology, 39 (132), 357372 (1993). 
