On the transport properties of natural and mixed convective flow fields

Turbulence is present in many natural processes where plays a relevant role as in the spread of pollutants in the atmosphere and oceans. It is also present in industrial processes and is the main conductor in industrial mixers among others.

In many of these natural or industrial systems, not only turbulence but also a difference of temperatures can dominate their behavior. This fact provokes lots of research about the combination of both factors: turbulent flows with thermal convection.

Our aim is the experimental study of the transport of heat and momentum in natural thermal convective flows and mix convention where the thermal convection is enhanced by becoming the flow turbulent.

For that, we have built an octagonal convection cell of diameter $D$ = 325 mm and height $H$ = 430 mm filled by water. The temperature is controlled by two plates: the hot one below and the cold one on top. To create turbulence, two mesh grids inside the tank are operated from both plates.

The flow field is measured in 3D thanks to the implementation of a Lagrangian tracking of the tracers seeded in the fluid followed by 4 monochromatic cameras. In addition, the temperature field is measured in 2D seeding the fluid with TLCs that change their color with the temperature and are recorded by a color camera.