The dynamics of a line plume confined by a single inclined boundary

A buoyant turbulent line plume developing from a source on a horizontal plane boundary in an unconfined environment will rise vertically, spreading linearly with height as it entrains fluid from the surroundings. If the plume instead develops from a source on an inclined plane, it might be anticipated that the flow behaviour will remain largely unaffected unless the inclination of the plane is sufficiently steep that the plume perimeter impinges on the boundary. We will show, however, that the presence of such a boundary dramatically alters the flow dynamics at much shallower inclinations. Indeed, in this experimental study two novel flow configurations with non-vertical plume trajectories have been identified, which thereby enable the parameter space of boundary inclination to be divided into three distinct regimes of plume behaviour. Furthermore, we will put forward insights into how the presence of the boundary modifies the entrainment flow into the plume. Such insights have allowed us to begin clarifying the physical mechanisms underlying the observed flow behaviours. The findings of this work have numerous potential applications across the engineered, and natural, world - for example in designing a natural ventilation scheme for a steeply-raked lecture theatre.