Experimental evidence of temperature gradients in cavitating microflows seeded with thermosensitive nanoprobes.
Thermosensitive fluorescent nanoparticles seeded in deionized water combined with confocal microscopy enables thermal mapping over three dimensions of the liquid phase flowing through a microchannel interrupted by a microdiaphragm. This experiment reveals the presence of a strong thermal gradient up to ~10(5) K/m only when hydrodynamic cavitation is present. Here hydrodynamic cavitation is the consequence of high shear rates downstream in the diaphragm. This temperature gradient is located in vortical structures associated with eddies in the shear layers. We attribute such overheating to the dissipation involved by the cavitating flow regime. Accordingly, we demonstrate that the microsizes of the device enhance the intensity of the thermal gap.
Laboratoire des Ecoulements Géophysiques et Industriels (LEGI), UMR5519 UJF Grenoble 1-CNRS, BP 53, 38041 Grenoble Cedex 9, France.
Frédéric
F
Ayela
Manuel
M
Medrano-Muñoz
David
D
Amans
Christophe
C
Dujardin
Thomas
T
Brichart
Matteo
M
Martini
Olivier
O
Tillement
Gilles
G
Ledoux