Analytical Blowup Solutions to the Pressureless Navier-Stokes-Poisson   Equations with Density-dependent Viscosity in R^N
  We study the N-dimensional pressureless Navier--Stokes-Poisson equations with density-dependent viscosity. With the extension of the blowup solutions for the Euler-Poisson equations, the analytical blowup solutions,in radial symmetry, in R^N are constructed. 
Manwai Yuen