Time-Depending Pitchfork Bifurcation in the Thermal Convection Flow Confined to an Isosceles Triangular Cavity Heated from Below

2006 ◽  
Author(s):  
El Hassan Ridouane ◽  
Antonio Campo
Keyword(s):  
Thermal Convection ◽  
Pitchfork Bifurcation ◽  
Convection Flow

Thermal Convection Bifurcation Within Isosceles Triangular Cavities

2007 ◽  
Author(s):  
El Hassan Ridouane ◽  
Antonio Campo
Keyword(s):  
Thermal Convection ◽  
Pitchfork Bifurcation ◽  
Critical Value ◽  
Mirror Plane ◽  
Maximum Height ◽  
Hysteresis Phenomenon ◽  
Conservation Equations ◽  
Symmetrical Solution ◽  
Steady Solutions ◽  
Volume Method

Laminar thermal convection of air confined to an isosceles triangular cavity heated from the base and symmetrically cooled from the upper inclined walls has been investigated numerically. The system of transient conservation equations, subject to the proper boundary conditions, along with the equation of state assuming the air behaves as a perfect gas are solved with the finite volume method. In the conservation equations, the second-order-accurate QUICK scheme was used for the discretization of the convective terms and the SIMPLE scheme for the pressure-velocity coupling. The maximum height-to-base aspect ratio A is fixed at 0.5, while the Grashof number extends from a low Gr = 103 to a high Gr = 106. The influence of Gr on the flow and temperature patterns is analyzed and discussed for two opposing scenarios, one corresponds to increasing Gr and the other corresponds to decreasing Gr. It is found that two steady-state solutions are possible, excluding their solution images through a vertical mirror plane. The symmetrical solution prevails for relatively low Grashof numbers. However, as the Gr is gradually increased, a transition occurs at a critical value of Gr. Above this critical value of Gr, an asymmetrical solution exhibiting a pitchfork bifurcation arises and eventually becomes steady. The existing ranges of these unsteady and steady solutions are reported for the two opposing scenarios. Also, issues related to the observed hysteresis phenomenon are discussed in detail.

scholarly journals Microparticle manipulation using laser-induced thermophoresis and thermal convection flow

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yang Qian ◽  
Steven L. Neale ◽  
John H. Marsh
Keyword(s):  
Thermal Convection ◽  
Particle Diameter ◽  
Optical Power ◽  
Jurkat Cells ◽  
Polystyrene Bead ◽  
Convection Flow ◽  
A Value ◽  
Fluidic Device ◽  
Walled Carbon Nanotubes

Abstract We demonstrate manipulation of microbeads with diameters from 1.5 to 10 µm and Jurkat cells within a thin fluidic device using the combined effect of thermophoresis and thermal convection. The heat flow is induced by localized absorption of laser light by a cluster of single walled carbon nanotubes, with no requirement for a treated substrate. Characterization of the system shows the speed of particle motion increases with optical power absorption and is also affected by particle size and corresponding particle suspension height within the fluid. Further analysis shows that the thermophoretic mobility (DT) is thermophobic in sign and increases linearly with particle diameter, reaching a value of 8 µm2 s−1 K−1 for a 10 µm polystyrene bead.

scholarly journals Visualization and Measurement of Thermal Convection Flow in a Closed Duct Excited by Acoustic Standing Wave

1998 ◽  
Vol 18 (Supplement2) ◽  
pp. 81-82
Author(s):  
Kenji NISHINO ◽  
Masaaki KAWAHASHI ◽  
Hiroyuki HIRAHARA ◽  
Yuusuke KUNIBA
Keyword(s):  
Standing Wave ◽  
Thermal Convection ◽  
Convection Flow ◽  
Acoustic Standing Wave

Experimental investigation on the chaotic phenomena in the wake of a natural thermal convection flow

2000 ◽  
Vol 16 (2) ◽  
pp. 121-127
Author(s):  
Lin Zhenbin ◽  
Guo Dahua ◽  
Yu Xilong ◽  
Zhu Jinsheng
Keyword(s):  
Experimental Investigation ◽  
Thermal Convection ◽  
Convection Flow ◽  
Chaotic Phenomena
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