Asynchronous rotation in binary stars produces non-radial oscillations that are known to cause observable variability on orbital timescales .
The horizontal perturbations of the surface velocity fields are referred to as “ tidal flows ” .
In this paper we illustrate the manner in which tidal flows perturb the surface velocity field from that of uniform rotation , using a one-layer stellar model for the calculations .
We justify the validity of this simplified model by the striking similarity between the photospheric absorption line-profiles it predicts and observational data of the binary system \alpha Virginis .
The velocity perturbations are used to compute the mechanical energy dissipation rates , \dot { E } , due to the shearing flows for the case of a massive ( 50 + 28 M _ { \odot } ) binary system having a moderately eccentric ( e = 0.3 ) orbit .
The largest value of \dot { E } around periastron phases is found on the hemisphere facing the companion .
However , at other orbital phases the maximum \dot { E } may migrate towards the poles .
Assuming that \dot { E } plays a role in the mass-loss characteristics of massive binary systems , this suggests that peculiar binaries such as HD 5980 and \eta Carinae may have a highly non-spherically symmetric mass-loss distribution which , in addition , is time-variable .