Transition to and from Turbulence in a Vertical Heated Pipe

The transition from laminar to turbulent flow in a pipe remains one of the oldest outstanding problems in fluid mechanics. In a vertically-aligned pipe, under the influence of heating, the opposite process has been observed, i.e. turbulence may be partially or fully suppressed by buoyancy forces. As the suppression of turbulence leads to severe heat transfer deterioration, this phenomenon is undesirable in both heating and cooling applications, such as nuclear reactor cooling systems and geothermal energy capture. In this talk, I will present our recent advances in understanding, predicting and optimising the phenomenon of relaminarisation due to buoyancy forces through the mathematical framework of dynamical systems theory and the use of modern stability-analysis tools. Connections to turbulence control strategies in ‘ordinary’ (isothermal) pipe flow will also be discussed, where, instead, turbulence suppression is typically highly desirable, as it leads to drag reduction and lower energy consumption.