Author(s): Stefano Lanzini; Massimo Marro; Samuel Vaux; Mathieu Creyssels; Pietro Salizzoni
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Keywords: Gravity currents; Heating; Convection; Sea-breeze
Abstract: Despite gravity currents propagation has been experimentally investigated under a wide range of ambient conditions (e.g. homogeneous, stably stratified, rotating, or non-zero background turbulence fluid) and wall characteristics (e.g. different slopes and roughness), one scenario representative of numerous realistic situations has received limited attention: the propagation of gravity currents over non-adiabatic walls. A relevant example of this condition can be found in atmospheric gravity currents, such as sea-breeze fronts or thunderstorm outflows, which are influenced by the earth's sensible heat flux. For instance, field measurements by Simpson et al. (1977) showed that sea-breeze fronts decelerate around midday and accelerate toward the evening, when the heating from the earth's surface decreases. Similarly, the experimental model by Cenedese and Monti (2003) revealed that the structure of sea-breeze fronts can be significantly altered when they interact with the urban heat island produced by cities. To advance the understanding of this problem, we present a laboratory study in which a gravity current produced by a steady flux of buoyancy (i.e. “sustained”) propagates over a heated surface. Particular focus is given on characterizing the front's propagation velocity as a function of the non-dimensional governing parameters of the flow.
Year: 2025