植物木质部导管与管胞微结构流场建模与流阻特性研究

发布时间：2018-06-26 01:39

本文选题：导管 + 管胞　；参考：《浙江工业大学》2016年博士论文

【摘要】：水分是植物细胞的重要成分,也是植物光合、呼吸作用的原料和各种生理生化反应和物质运输的介质,水分必须从植物根部沿着体内木质部通道运输到冠层才能参与这些反应。深入研究植物内水分传输机理对有效地提高植物水分利用效率具有重要意义。长期以来对植物体内水分传输的研究主要是通过植物学解剖和观测试验,由于植物体内输水管道尺寸微小、结构复杂,单凭传统的植物生理学手段很难从微观角度探析植物体内部复杂的流动现象和传输机理。因此,本文以植物木质部导管和管胞输水微结构为研究对象,从流体力学的角度分析植物体内水分传输机理。采用流体建模、数值模拟与试验研究相结合的研究方法,探析体内复杂流场分布情况以及各种组织结构对植物流阻特性的影响,为更深入地研究植物体内水分运移的机理提供重要的理论依据。本文主要研究内容如下:(1)分析了植物木质部导管和管胞等输导组织的结构特征和水动力特性,在此基础上,对影响植物导管和管胞水分流动性能的沿程阻力因素和局部阻力因素进行分析,并研究了管道直径大小和截面形状对导管和管胞流动性能的影响。(2)为研究木质部导管、管胞中微结构对内部流场特性的影响,对管壁增厚、端壁梯状穿孔板和塞-缘结构具缘纹孔等结构分别建立了伯努利流体动力学模型,分析结构参数与流阻系数之间的关系,并通过数值模拟研究了植物体内水分传输的压降、速度和流量等流场分布情况,以及不同的木质部结构对流阻特性的影响规律。(3)针对管胞纹孔水分流动过程中纹孔膜的受力变形问题,考虑水分流动和纹孔膜受力变形的耦合作用,基于双向同步求解方法对纹孔内部流场和纹孔膜结构进行联合求解,分析了不同的入口压力驱动下纹孔内流场的动态特性以及纹孔膜的应力和变形情况,并讨论了流固耦合作用对纹孔流量的影响。(4)根据流体力学相似性原理,搭建了植物组织输水模拟实验装置。采用选择性激光烧结快速成型加工方法(Selective Laser Sintering,SLS),对导管、管胞内部结构模型进行整体成型加工,通过模拟实验分析管壁增厚、穿孔板和纹孔等结构的流动阻力特性,并将试验结果与仿真分析结果进行比较。
[Abstract]:Water is an important component of plant cells, and it is also the raw material of photosynthesis, respiration and various physiological and biochemical reactions and the medium of material transport. Water must be transported from the root of the plant to the canopy along the xylem channel of the body to participate in these reactions. It is very important to study the mechanism of water transport in plants to improve water use efficiency. For a long time, water transport in plants has been studied mainly through botany anatomy and observation experiments. Because of its small size and complex structure, It is difficult to analyze the complex flow phenomenon and transport mechanism of plant body from microcosmic point of view by traditional plant physiology. Therefore, the mechanism of water transport in plants was analyzed from the point of view of hydrodynamics, taking the microstructures of xylem ducts and tracheids as the research objects. By using the method of fluid modeling, numerical simulation and experimental study, the distribution of complex flow field in the body and the influence of various tissue structures on the flow resistance characteristics of plants are analyzed. It provides an important theoretical basis for the further study of the mechanism of water migration in plants. The main contents of this paper are as follows: (1) the structural and hydrodynamic characteristics of the ducts and tracheids in plant xylem were analyzed. The factors affecting the water flow performance of plant ducts and tracheids were analyzed, and the effects of diameter and section shape of pipes on the flow properties of ducts and tracheids were studied. (2) in order to study xylem ducts, The effect of microstructures in tracheids on the characteristics of internal flow field was studied. Bernoulli fluid dynamics models were established for the thickening of tube wall, the perforation plate of end-wall ladder and the ribbed hole of stop-edge structure, respectively, and the relationship between the structural parameters and the flow resistance coefficient was analyzed. The distribution of pressure drop, velocity and flow rate of water transport in plant was studied by numerical simulation. And the influence of different xylem structure on convection resistance. (3) considering the coupling effect of water flow and pore membrane deformation in the process of water flow in tracheid pore. Based on the bidirectional synchronous solution method, the internal flow field and the membrane structure of the grooves are solved jointly. The dynamic characteristics of the internal flow field and the stress and deformation of the perforated membrane driven by different inlet pressures are analyzed. The effect of fluid-solid coupling on the pore flow rate was discussed. (4) according to the principle of hydrodynamics similarity, a plant tissue water conveyance simulation device was set up. Selective laser sintering rapid prototyping (SLS) was used to process the internal structure model of tube and tracheid. The flow resistance characteristics of tube wall thickening, perforated plate and perforated hole were analyzed by simulation experiment. The experimental results are compared with the simulation results.
【学位授予单位】：浙江工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q945

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