Water Transport Mechanism And Simulation In Plant

Water is an important component of plant cell,raw material of photosynthesis and respiration.It is also a media of physiological and biochemical reaction and material transport.In order to improve efficiency of water use of plant in the limits of water environment,studies of water transport mechanism in plant should be carried deeply.After the studies of structure of xylem,water transport mechanism,physiological model,the results were as follows:the vessel sizes were 20μm～500μm and the sap flow Reynold numbers were 0.03～1.2.Based on theory above,water transport model in plant was founded.The models was side straight pipe with 400μm×400μm cross-section.Water transport in plant was simulated by experimental methods with Micro-PIV and numerical simulation when the Reynold numbers were 0.15,0.25,0.35 and 0.45 respectively.Simulation solutions by Micro-PIV showed that velocity of liquid flow in the direction of cross-section approximates to parabola,the curve of which was gentle,as the velocity got higher,the curve got more bent.The rough elements had some influences on water flow,which were more near the wall and less in the centre of the pipe.Approximate solutions of laminar flow in side straight pipe and the simulation solutions by Micro-PIV were compared.The former were larger near the wall. Approximate solutions of laminar flow was acquired in the conventional channel, while,in the micro channel,the velocity of water decreased near the wall as the influences of rough elements on water flow got larger.Porous media model was carried to simulate the water transport in plant.To simulate the influences of rough elements on water flow,momentum source term was added to control-equations in porous media model.As the Reynold number of water transport in plant is so small,the viscosity term was calculated and the inertial term was ignored in momentum source term of porous media model.The simulated solutions with different porous media thickness which were 40μm,60μm,80μm, 100μm,120μm,140μm and 160μm were compared,and the solution with thickness of 60μm was best.The simulated solutions of porous media model were in line with the results by Micro-PIV.