  Linear stability analysis currently fails to predict turbulence transition in
canonical viscous flows. We show that two alternative models of the boundary
condition for incipient perturbations at solid walls produce linear
instabilities that could be sufficient to explain turbulence transition. In
many cases, the near-wall behavior of the discovered instabilities is
empirically indistinguishable from the classical no-slip condition. The ability
of these alternative boundary conditions to predict linear instabilities that
are consistent with turbulence transition suggests that the no-slip condition
may be an overly simplified model of fluid-solid interface physics,
particularly as a description of the flow perturbations that lead to turbulence
transition in wall-bounded flows.
