Interactions Between a Discrete Convective Element and a Shearing Environment: A Numerical Simulation

The effects of vertical shear on the evolution of an element of dry thermal convection are investigated by numerically integrating an appropriate set of equations. The study examines the effects of different magnitudes of uniform shear as well as exponential and jet-like wind profiles. Vertical shear inhibits the growth and maximum vertical velocity of the thermal in proportion to the magnitude of the shear. The maximum horizontal inflow is increased for all except the strongest of shears. The characteristic toroidal circulation of the thermal remains in evidence under even the most severe shearing deformation. The center of the toroidal circulation and the center of buoyancy of the thermal refuse to rise through a jet, but vertical motions do rise through the jet and decrease the intensity of the jet by transporting momentum away from it. Circulations developed by interaction with the jet are longer lived than in the other shearing environments because of a flow instability. The experiments produced results that agree with those of previous investigators, despite vast differences in experimental technique.