  We investigate the criticality of the jamming transition for overdamped
shear-driven frictionless disks in two dimensions for two different models of
energy dissipation: (i) Durian's bubble model with dissipation proportional to
the velocity difference of particles in contact, and (ii) Durian's "mean-field"
approximation to (i), with dissipation due to the velocity difference between
the particle and the average uniform shear flow velocity. By considering
velocity correlations, finite-size behavior of pressure, and the pressure
analog of viscosity, we argue that these two models share the same critical
behavior.
