Tree hydraulics: how sap rises

作者：Mark Denny · 发表于：European Journal of Physics · 年份：2011 · DOI：10.1088/0143-0807/33/1/003 · 被引用次数：17 · 研究领域：Plant Water Relations and Carbon Dynamics、Soil and Unsaturated Flow、Sports Dynamics and Biomechanics

Trees transport water from roots to crown—a height that can exceed 100 m. The physics of tree hydraulics can be conveyed with simple fluid dynamics based upon the Hagen–Poiseuille equation and Murray's law. Here the conduit structure is modelled as conical pipes and as branching pipes. The force required to lift sap is generated mostly by transpiration or capillary action; we investigate the effectiveness of both these forces for the two conduit architectures considered. The level of analysis is appropriate for undergraduates. The subject is of broad interest because it provides a naturally-occurring example of an unusual metastable state of matter: liquid under tension.