论文标题
瑞利 - 贝纳德对流的政权跨界与混合边界条件的对流
Regime crossover in Rayleigh-Benard convection with mixed boundary conditions
论文作者
论文摘要
我们在数值上模拟了三维雷利 - 贝纳德对流，从下方加热并从上方冷却的流体层中的流动，并具有不均匀的温度边界条件，以探索最近文献中描述的两个不同的方案。我们将非二维温度差（即〜Rayleigh号码）固定为$ ra = 10^8 $，并将prandtl数字在$ 1 $和$ 100 $之间变化。通过在顶板上引入绝热边界条件的条纹，并使顶板的表面仅$ 50 \％$ contoving，我们可以修改传热，平均温度剖面和基础流量。我们发现两个机制：当图案波长很小时，流量几乎不受条纹影响。传热降低，但仍然是未修饰的情况的很大一部分，而下面的流量仅略微修改。当图案波长较大时，热传递饱和到未修饰问题值的大约三分之二的三分之二时，大容量的温度大大升高，并且在指示上正常的速度波动增强了。两种状态之间的过渡发生在两个板之间的距离周围的模式波长下发生，并且在略有不同的波长值下过渡量不同。即使长波长状态中的统计数据略有变化，这种过渡也大致无关。
We numerically simulate three-dimensional Rayleigh-Bénard convection, the flow in a fluid layer heated from below and cooled from above, with inhomogeneous temperature boundary conditions to explore two distinct regimes described in recent literature. We fix the non-dimensional temperature difference, i.e.~the Rayleigh number to $Ra=10^8$, and vary the Prandtl number between $1$ and $100$. By introducing stripes of adiabatic boundary conditions on the top plate, and making the surface of the top-plate only $50\%$ conducting, we modify the heat transfer, average temperature profiles and the underlying flow properties. We find two regimes: when the pattern wavelength is small, the flow is barely affected by the stripes. The heat transfer is reduced, but remains a large fraction of the unmodified case, and the underlying flow is only slightly modified. When the pattern wavelength is large, the heat transfer saturates to approximately two-thirds of the value of the unmodified problem, the temperature in the bulk increases substantially, and velocity fluctuations in the directions normal to the stripes are enhanced. The transition between both regimes happens at pattern wavelength around the distance between two plates, with different quantities transitioning at slightly different wavelength values. This transition is approximately Prandtl number independent, even if the statistics in the long-wavelength regime slightly vary.
