Heat transfer and hydrothermal fluid flow at flanges on large seafloor sulphide structures

I present some fluid dynamical calculations which quantify the convective heat transfer at overflowing flanges that grow on large sulphide structures in the Endeavour hydrothermal field of the Juan de Fuca Ridge [1, 2]. I show that natural convection in the seawater extracts tens of kilowatts of heat from the top, edge and bottom of a flange, while the flow of hydrothermal fluid over the rim of the flange produces an advected heat flow of the order of 103 kW. I predict that overflow at the rim will maintain a thermal boundary layer at the interface between the ponded hydrothermal fluid and the underlying seawater that is only a few millimetres in thickness. I also demonstrate that the sharpness of this thermal boundary layer and the large refractive index contrast across it are responsible for its observed mirror-like nature [1].