Lipps, F. B., 1971: Two-dimensional numerical experiments in thermal convection with vertical shear. Journal of Atmospheric Sciences, 28 (1), 3-19.
Abstract: The dynamics of thermal convection through a shallow layer with vertical
shear is examined using an idealized numerical model. The convection is
assumed to take the form of two-dimensional rolls. The mean shear flow and
the unstable temperature gradient are maintained by no-slip, conducting
boundary conditions applied at the upper and lower boundaries of the model.
When the convective rolls are transverse to the mean current, the flow approaches
a steady state with time for the cases of primary interest. In agreement
with previous numerical studies the shear has a stabilizing influence on
the convection: the transformation of potential energy into disturbance
kinetic energy is reduced, and disturbance kinetic energy is transformed
into basic kinetic energy. A new result, in agreement with linear stability
theory, is that shear can significantly increase the horizontal distance
between disturbances over that expected with no shear.
Steady-state results were also obtained when the rolls are parallel to
the mean current. In this case basic kinetic energy is transformed into
disturbance kinetic energy. Results for momentum transfer and heat transfer
obtained from the present numerical model are compared with the experimental
results of Ingersoll. This comparison suggests that for low values of the
Rayleigh number his convection is primarily in the form of rolls parallel
to the shear flow. However, for Rayleigh numbers >20,000 the experimental
and numerical results start to diverge, suggesting that three-dimensional
effects are becoming important in this range.