Megan Davies Wykes - University of Cambridge In this talk I'll describe the mixing induced by plumes in boxes, using the simple example of the filling box and the emptying-filling box to demonstrate the differences in the maximum mixing efficiency in an open and closed system. I will also present the results of numerical simulations, that allow us to examine the spatial variation of background potential energy production and viscous dissipation in a confined plume, an example that lets us see how the definition of background potential energy emphasises the energetic importance of mixing that occurs close to the mean density.