TY - JOUR
T1 - Three-dimensional thermoconvection from a non-uniformly heated plate near the liquid-vapor critical point
AU - Shen, B.
AU - Zhang, P.
N1 - Funding Information:
This research is supported by the National Natural Science Foundation of China under Contract No. 51376128 . B. Shen gratefully acknowledges financial support by World Premier International Research Center Initiative (WPI), MEXT , and International Institute for Carbon-Neutral Energy Research (WPI-I 2 CNER), Kyushu University, Japan.
Publisher Copyright:
© 2014 Elsevier Masson SAS.
PY - 2015/3
Y1 - 2015/3
N2 - Three-dimensional buoyancy-driven convection close to the liquid-vapor critical point is numerically investigated. We consider a supercritical nitrogen-filled rectangular cavity with horizontal/vertical aspect ratios of 3:1 and 2:1, which is heated differentially at the bottom by a constant heat flux of 10 W/m2. Dependent on the size of the heating area (covering, namely, the full, a half, and a quarter of the bottom wall, respectively), spatiotemporal descriptions of the development of hydrodynamic instabilities are obtained for both near-critical and weakly-critical fluid conditions based on real-fluid properties, which include the vortex cores educed by the second invariant of the velocity gradient tensor. Direct numerical simulations are performed on a hydrodynamic model modified by the low-Mach-number approximation using a finite volume-based SIMPLE method. In addition, a co-located multigrid strategy is adopted to accelerate the simulation. The results capture the influences of the distance to the critical point on the evolution of the flow pattern and convective heat transfer under increasingly more complex heating arrangements. The strong equivalency among different near-critical fluids is demonstrated by a comparison between Rayleigh-Bénard flows in supercritical nitrogen and CO2 with comparable degrees of criticality.
AB - Three-dimensional buoyancy-driven convection close to the liquid-vapor critical point is numerically investigated. We consider a supercritical nitrogen-filled rectangular cavity with horizontal/vertical aspect ratios of 3:1 and 2:1, which is heated differentially at the bottom by a constant heat flux of 10 W/m2. Dependent on the size of the heating area (covering, namely, the full, a half, and a quarter of the bottom wall, respectively), spatiotemporal descriptions of the development of hydrodynamic instabilities are obtained for both near-critical and weakly-critical fluid conditions based on real-fluid properties, which include the vortex cores educed by the second invariant of the velocity gradient tensor. Direct numerical simulations are performed on a hydrodynamic model modified by the low-Mach-number approximation using a finite volume-based SIMPLE method. In addition, a co-located multigrid strategy is adopted to accelerate the simulation. The results capture the influences of the distance to the critical point on the evolution of the flow pattern and convective heat transfer under increasingly more complex heating arrangements. The strong equivalency among different near-critical fluids is demonstrated by a comparison between Rayleigh-Bénard flows in supercritical nitrogen and CO2 with comparable degrees of criticality.
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U2 - 10.1016/j.ijthermalsci.2014.10.015
DO - 10.1016/j.ijthermalsci.2014.10.015
M3 - Article
AN - SCOPUS:84914182170
VL - 89
SP - 136
EP - 153
JO - Revue Generale de Thermique
JF - Revue Generale de Thermique
SN - 1290-0729
ER -