Abstract
Roll-type convection in a viscous Boussinesq fluid layer heated differentially at the
bottom is numerically investigated by a spectral model. The differential heating along the
bottom is assumed sinusoidal for the sake of simplicity.
Results are summarized as follows: a) as the horizontal temperature gradient increases,
Rayleigh convection cells tend to be deformed so that reinforced large (so-called) direct cells
and suppressed small indirect cells stand alternately; b) the horizontal temperature gradient
acts to suppress the vertical heat transport due to convective rolls; c) as the horizontal
temperature gradient increases, the longer wave components of the spectrum tend to be
intensified; d) when stable and unstable regions exist side by side, the Rayleigh-type con
vection seems to develop in the unstable region only if the width of the unstable region
exceeds that of Rayleigh convection cells in qualitative agreement with our experimental
observations (Part I).
