TROCONVEX: Turbulent rotating convection to the extreme

Aim: Laboratory investigation of the various behavioural regimes in extreme, turbulent rotating Rayleigh-Bénard convection

Many geophysical and astronomical phenomena are driven by highly turbulent fluid dynamics. These dynamics are often driven by the buoyant rising and falling of fluids of different densities, known as convection, and strongly affected by the rotation of the celestial body through Coriolis forces.

One useful approach to understanding geophysical and astrophysical flows is to study a reduced problem known as “rotating Rayleigh-Bénard convection” in a laboratory setting. While studies of rotating convection began over a century ago, only recently have major developments occurred toward understanding the problem in settings of exceptionally strong rotation or convection, such as geophysical systems. Modern laboratory and numerical studies have found that many novel behaviours emerge only under extreme conditions.

Figure 1: Schematic of a rotating convection laboratory setup and example cases at increasingly strong thermal forcing.[1]

Figure 1 shows a typical experimental setup for investigating rotating convection, where a cylindrical tank of fluid is heated from below and cooled from above to induce buoyant instabilities, and rotated about its central axis to induce Coriolis forces. Depending on the relative strength of the thermal forcing compared to rotational forcing (quantified as "Ra/Racrit­" in Figure 1), the flow takes on different morphologies, heat transfer properties, and velocity scales. Figure 1 shows laboratory flow visualizations in an extreme setting, where several of these distinct behavioural regimes manifest.[1]

 

 

 

 

Figure 2: TROCONVEX design schematic, with person for scale.

Figure 2 shows the design schematic for TROCONVEX (Turbulent Rotating Convection to the Extreme), the new rotating convection device at TU/e. With a maximum tank height of 4 meters, TROCONVEX can generate stronger convective and rotational forces than any other laboratory rotating convection device to date. Using heat transfer measurements and Particle Image Velocimetry (PIV) techniques, we will elucidate the fluid physics governing the unexplored regimes of rotating convection that arise in such extreme conditions.

[1] J.S. Cheng et al., 2015, Geophys. J. Int., 201, 1-17.

Group members

Jonathan Cheng, Andrés Aguirre, Rudie Kunnen