Analytical Blowup Solutions to the 4-dimensional Pressureless   Navier-Stokes-Poisson Equations with Density-dependent Viscosity
  We study the 4-dimensional pressureless Navier--Stokes-Poisson equations with density-dependent viscosity. The analytical solutions with arbitrary time blowup, in radial symmetry, are constructed in this paper. 
Manwai Yuen