Viscous flow of craters

The viscous flow equations of Haskell describing the very slow axially symmetric flow of a linearly viscous liquid initially subject to a crater-shaped surface disturbance have been solved numerically. The solution is presented in a curve showing the return of the center of the perturbation to the original surface level as a function of time. A discussion of the stability of this type of viscous flow is given, together with a stability criterion due to Tait. Application of the results to lunar craters is considered, and finally a description is given of some viscous flow model studies, which may be of value in the solution of more complex viscous flow problems of this type.