  We confirm numerically that the Johnson-Segalman model is able to reproduce
the continual oscillations of the falling sphere observed in some viscoelastic
models. The empirical choice of parameters used in the Johnson-Segalman model
is from the ones that show the non-monotone stress-strain relation of the
steady shear flows of the model. The carefully chosen parameters yield
continual, self-sustaining, (ir)regular and periodic oscillations of the speed
for the falling sphere through the Johnson-Segalman fluids. In particular, our
simulations reproduce the phenomena: the falling sphere settles slower and
slower until a certain point at which the sphere suddenly accelerates and this
pattern is repeated continually.
