Experimental studies on transient features of natural convection in particles suspensions

• Published in: International journal of heat and mass transfer 2005-07, Vol.48 (14), p.2933-2942
• Main Authors: Chen, B., Mikami, F., Nishikawa, N.
• Format: Article
• Language: English
• Subjects: Convection and heat transfer; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Multiphase and particle-laden flows; Nonhomogeneous flows; Physics; Turbulent flows, convection, and heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2004.11.016

Particle Tracking Velocimetry (PTV), in conjunction with the refractive index matching technique and laser induced fluorescent (LIF) tracer particles, was used to overcome the visualization problem in a particle suspension. A square test section was filled with the particle suspension and impulsively heated from the bottom wall while the two facing vertical walls were kept at a constant temperature. The two-dimensional velocity fields, particle distributions in a plane and the wall temperature fields were visualized simultaneously using three cameras. The results showed peculiar flow patterns such as the formation and vanishing of two-layer convection cells which were distinct from those in a clear, particle-free fluid. Sedimentation driven convection is thought to be the fundamental mechanism for the formation of these two layer convection cells. The overlying particle-free-layer convection was started by the release of the heated clear fluid at the interface between the particle-free layer and the suspension.