Vapor Flux on Bumpy Surfaces: Condensation and Transpiration on Leaves
Vapor Flux on Bumpy Surfaces: Condensation and Transpiration on Leaves
复制标题
凹凸不平表面上的蒸汽通量：叶子上的冷凝和蒸腾
DOI：
10.1021/acs.langmuir.1c00473
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Jung, Sunghwan
中科院分区：
文献类型：
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作者：
Jung, Sunghwan
液滴冷凝和蒸发是由水蒸气浓度梯度引起的，在工程和自然系统中都很重要。一个有趣的自然例子是植物叶子上的蒸腾作用。叶片内部空间中的大部分水通过气孔逸出，其速率取决于表面地形以及叶片内部和外部的蒸汽浓度差异。以前的研究在各种表面上的蒸汽通量集中在数值求解蒸汽扩散方程或使用缩放参数的基础上一个简单的解决方案与平坦的表面。在目前的工作中，我们提出并讨论了各种二维表面形状（例如，半圆柱、半椭圆、头发）。求解扩散方程的方法是使用复势理论，该理论提供了蒸气浓度和通量的解析解。我们发现，高质量流量的水蒸气形成的顶部附近的微结构，而低质量流量的气孔附近的叶片表面。气孔附近如此低的水蒸气通量可能以两种方式影响蒸腾作用。首先，气孔上的冷凝液滴不会生长，这是由于低质量的蒸汽通量，这不会抑制通过气孔开口的气体交换。其次，来自大气的低质量通量将促进高浓度水汽从气孔下空间的释放。
Drop condensation and evaporation as a result of the gradient in vapor concentration are important in both engineering and natural systems. One of the interesting natural examples is transpiration on plant leaves. Most of the water in the inner space of the leaves escapes through stomata, whose rate depends on the surface topography and a difference in vapor concentrations inside and just outside of the leaves. Previous research on the vapor flux on various surfaces has focused on numerically solving the vapor diffusion equation or using scaling arguments based on a simple solution with a flat surface. In this present work, we present and discuss simple analytical solutions on various 2D surface shapes (e.g., semicylinder, semiellipse, hair). The method of solving the diffusion equation is to use the complex potential theory, which provides analytical solutions for vapor concentration and flux. We find that a high mass flux of vapor is formed near the top of the microstructures while a low mass flux is developed near the stomata at the leaf surface. Such a low vapor flux near the stomata may affect transpiration in two ways. First, condensed droplets on the stomata will not grow due to a low mass flux of vapor, which will not inhibit the gas exchange through the stomatal opening. Second, the low mass flux from the atmosphere will facilitate the release of highly concentrated vapor from the substomatal space.