Stability and evolution of a dry spot

The motion of a thin viscous layer of fluid on a horizontal solid surface b ounded laterally by a dry spot and a vertical solid wall is considered. A l ubrication model with contact line motion is studied. We find that for a co ntainer of fixed length the axisymmetric equilibrium solutions with small d ry spots are unstable to axisymmetric disturbances. As the size of the dry spot increases, the equilibrium solutions become unstable to nonaxisymmetri c disturbances. In addition, we present numerical solutions of the nonlinea r evolution equations in the axisymmetric and nonaxisymmetric cases for dif ferent values of the parameters. The axisymmetric results show good agreeme nt with existing experimental results. (C) 2001 American Institute of Physi cs.