THERMAL COMPRESSION WAVES .2. MASS ADJUSTMENT AND VERTICAL TRANSFER OF TOTAL-ENERGY

A fully compressible model is used to simulate the mass adjustment tha t occurs in response to a prescribed heat source. Results illustrate t he role that thermal compression waves have in this process. The verti cal mass transport associated with compression waves decreases rapidly with height. Most of the mass transport occurs in the horizontal, wit h the vertical structure of the disturbance similar to that of a Lamb wave. The vertical transfer of total energy in a thermally driven mixe d layer is also examined. It is shown that the upward transport of tot al energy is accomplished by a compression effect rather than by the e xchange of warm and cold air by buoyant thermals, Model results are an alysed to determine budgets of total energy, mass and entropy. It is d emonstrated that buoyant thermals are predominantly responsible for a transfer of entropy, rather than total energy. In the light of these r esults the notion of 'heat transport' in a fluid is discussed.