Summary

Turbulent natural convection in cavities has been extensively studied due to its importance in various technological applications, such as cooling of electronic components, insulation of nuclear reactors, thermal comfort in buildings and compartments of refrigerators. This master?s thesis reports an experimental investigation of turbulent natural convection in a parallelepiped cavity. The cavity has an aspect ratio height/width equal to four and a square base, with the vertical walls maintained at different temperatures, resulting in a Rayleigh number equal to 1.14 x 1010. Measurements of velocity and Reynolds stresses were carried out via laser Doppler velocimetry (LDV) in different sections of the cavity. The flow was found to be restricted within a very narrow region next to vertical walls, with higher levels of velocity next to the hot wall. Unexpectedly, fluid flow was seen to be upwards after a very thin layer of descending flow along the cold wall. With reference to profiles of vertical velocity component and flow images acquired through PIV, it was observed that this phenomenon is probably associated with a fluid intrusion traveling upwards. PIV measurements also indicate the presence of vortices moving along both vertical walls.

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