Weak solution for the Hele-Shaw problem: viscous shocks and singularities
S-Y. Lee, R. Teodorescu+, P. Wiegmann*
Mathematics 253-37, Caltech, Pasadena, CA 91125, USA
+Mathematics Department, Univ. of South Florida, 4202 Tampa FL 33620, USA
*The James Franck Institute, University of Chicago, 5640 Chicago IL 60637, USA
Abstract
In Hele-Shaw flows a boundary of a viscous fluid develops unstable
fingering patterns. At vanishing surface tension, fingers evolve to
cusp-like singularities preventing a smooth flow. We show that the
Hele-Shaw problem admits a weak solution where a singularity triggers
viscous shocks. Shocks form a growing, branching tree of a line
distribution of vorticity where pressure has a finite discontinuity. A
condition that the flow remains curl-free at a macroscale uniquely determines
the shock graph structure. We present a self-similar solution describing
shocks emerging from a generic (2,3)-cusp singularity - an elementary
branching event of a branching shock graph.