Transition to and from turbulence in a vertical heated pipe

Flows through pipes or channels play a vital role in energy systems by enabling heat transfer between components to facilitate power generation, heating or cooling, and chemical production. In a vertical configuration, buoyancy forces can assist the flow, but they may also suppress turbulence and dramatically degrade heat transfer. Despite the relatively simple geometry, buoyancy complicates the prediction and control of both the flow state and thermal performance, leading to rich dynamics that are not yet fully understood. 

In this talk, I will discuss our recent efforts to model and understand transitional and turbulent flows in a vertical heated pipe, focusing on the competition between shear- and buoyancy-driven instabilities and the resulting suppression or enhancement of coherent structures. Using tools from dynamical systems theory, stability analysis, and optimisation methods, I will show how we can gain insight into the mechanisms driving transitions between flow regimes and inform strategies to suppress or promote turbulence under varying thermal conditions. Drawing parallels with isothermal pipe flow, I will highlight common and distinct features in the mechanisms that trigger and sustain turbulence in both systems, with a view to controlling turbulence for drag reduction and/or heat transfer enhancement.

Venue: Fulton G20