  The solar tide in an ancient Venusian ocean is simulated using a dedicated
numerical tidal model. Simulations with varying ocean depth and rotational
periods ranging from -243 to 64 sidereal Earth days are used to calculate the
tidal dissipation rates and associated tidal torque. The results show that the
tidal dissipation could have varied by more than 5 orders of magnitude, from
0.001--780 Gigawatts, depending on rotational period and ocean depth. The
associated tidal torque is about 2 orders of magnitude below the present day
Venusian atmospheric torque, and could change the Venusian day length by up to
72 days per million years depending on rotation rate. Consequently, an ocean
tide on ancient Venus could have had significant effects on the rotational
history of the planet. These calculations have implications for the rotational
periods of similarly close-in exoplanetary worlds and the location of the inner
edge of the liquid water habitable zone.
