  A binary Bose-Einstein condensate of cold atoms, with sufficiently strong
intercomponent repulsion resulting in spatial segregation, is investigated
numerically. Configurations as a multiple quantum vortex in one component are
considered, with vortex core filled by the other component. An efficient radius
of the core may exceed the width of the transient layer between the components,
and then an analogy with a filled cylindrical vortex in classical hydrodynamics
of two immiscible perfect fluids takes place. The analogy allows us to analyze
for the condensate filled vortex the longitudinal "sausage" instability, and
the transverse instability caused by the "tangent shock", as well as a stable
regime in the parametric gap between the instabilities. Long-lived coherent
structures appearing in some cases on the nonlinear stages of both
instabilities are observed numerically.
