Ultimate regime of high Rayleigh number convection in a porous medium.
Ultimate regime of high Rayleigh number convection in a porous medium.
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DOI：
10.1103/physrevlett.108.224503
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发表时间：
2012-05
影响因子：
8.6
通讯作者：
D. Hewitt;J. Neufeld;J. Lister
中科院分区：
文献类型：
--
作者：
D. Hewitt;J. Neufeld;J. Lister
本文给出了多孔介质中瑞利数Ra≤4×10(4)时二维瑞利- b<s:1>纳德对流的高分辨率直接数值模拟，结果表明，与先前的指示相反，努塞尔数Nu~Ra的线性经典标度是渐近的。通过对强对流系统的流动动力学分析，表明采用单水平波数k和线性背景温度场的简单柱状“换热器”模型，强对流系统内部的Ra→∞描述越来越好。数值结果用k~Ra（0.4）近似拟合。
Well-resolved direct numerical simulations of 2D Rayleigh-Bénard convection in a porous medium are presented for Rayleigh numbers Ra≤4×10(4) which reveal that, contrary to previous indications, the linear classical scaling for the Nusselt number, Nu~Ra, is attained asymptotically. The flow dynamics are analyzed, and the interior of the vigorously convecting system is shown to be increasingly well described as Ra→∞ by a simple columnar "heat-exchanger" model with a single horizontal wave number k and a linear background temperature field. The numerical results are approximately fitted by k~Ra(0.4).