Study On The Flow Resistance Characteristics Of Xylem Vessel Microstructures In Angiosperm

The microstructure of plant xylem is an important factor affecting water transmission within plants and attracts attention due to its central position in the soilplant-atmospheric continuous system(SPAC).The xylem vessel structure is small and complex,making the calculation of water transport inside the xylem difficult.At present,fluid dynamics simulation method is often used to simulate the characteristics of water transport in xylem structure,but in practice,it faces the following problems: 1.The study of xylem microstructure is single,and the result of only one structure is far from the actual situation of plants.2.The source of dimensional parameters of plant xylem structure is not accurate enough,and the real parameters of tissue structure are not measured by experimental anatomy,so that the numerical simulation results cannot accurately reflect the real situation of plants in nature.In order to deal with the above difficulties and more accurately simulate the water flow in plants,this paper measured the vessel microstructure parameters of angiosperm Magnolia by experimental anatomy method,and built 1:1 scale models of the thickened wall structure,perforated plate structure and perforated hole structure of the vessel observed in plant slices,adjusted different parameters and carried out fluid mechanics simulation calculation on the model,based on the fluid pressure drop and flow value in the vessel calculated by simulation,Analyze the effects of thickened wall structure,perforated plate structure,and perforated hole structure of different parameters on flow resistance and flow regime.The main conclusions are as follows:(1)The main factors affecting the flow resistance of the vessel microstructure are explored: the thickening wall structure is the most affected by the grain height and the least affected by the grain width;the hole number and the thickness are the main factors of the perforation plate structure,and the main factors affect the flow resistance of the perforation structure.(2)In the analysis of the influence of different microstructures on the vessel flow resistance proportion: the perforated plate is the main factor causing the flow resistance,accounting for 39.17% of the total resistance.When the thickened wall structure,the total pressure drop increases by 64.70% and the flow resistance increases by 64.38%;the pore structure is the main reason for the decrease of flow resistance by53.11% of the total resistance,the total pressure drop decreases by 67% and the flow resistance by 53.11%.(3)In exploring the radial transmission efficiency of the vessel microstructure:the length of the pore domain is the main factor affecting the radial transmission efficiency of the vessel.When the pore domain length increases from 100 μm to 300μm,the radial transmission efficiency increases from 43.99% to 53.21%.The results provide a new model for exploring the water flow inside the xylem vessel.