A visual simulation method for researching xylem vessel water transport and evaporation process based on Fluent

Abstract

This invention provides a visualization simulation method based on Fluent for studying the long-distance water transport and evaporation process of plant xylem vessels. A three-dimensional evaporation model is constructed using ICEM in ANASYS Workbench software, and the corresponding mesh is drawn. Wall properties, fluid regions, and solid regions are set in the model. Then, mesh files of three models created using Mesh are imported into Fluent software. Environment variables are used for debugging, and a UDF for the evaporation rate is imported to write a program that applies the evaporation formula to the top water surface boundary. The calculation methods and fluid properties in the model are set using Fluent, and calculations are performed separately. The influence of wind speed on evaporation at different iteration time steps is compared to obtain a cloud map of gaseous water volume fraction. The spontaneous infiltration and evaporation process is explored and visualized using numerical simulation methods. This method is of great significance for simulating, predicting, and optimizing the spontaneous infiltration and evaporation process in oriented porous media models, including plant xylem vessels.

Description

Technical Field

[0001] This invention relates to a visualization simulation method for studying the water transport and evaporation process of xylem vessels in plants based on software, specifically a visualization simulation method based on Fluent for studying the water transport and evaporation process of xylem vessels. Background Technology

[0002] The xylem, as a long-distance, low-resistance water transport pathway in terrestrial plants, allows for the rapid and large-scale movement of water from roots to leaves, which is essential for maintaining gas exchange in leaves in relatively dry atmospheric environments. The xylem plays a vital role in enhancing the transport of water and minerals within the plant body.

[0003] Porous media models can be applied to many problems, such as flow through a medium-filled system, through filter paper, perforated disks, flow distributors, and pipe stacks. When using a porous media model, a cell region containing the porous medium must be defined, and the pressure loss of the flow is determined by the inputs in the momentum equation of the porous medium. Fluent software has made significant simplifications to the porous media model, mainly setting porosity, viscosity coefficient, and drag coefficient. Porosity is directly provided by the material supplier, while viscosity and drag coefficients can be obtained through several sets of experiments on pressure drop and velocity drop. If precision is not required or experimental conditions are unavailable, they can be approximated using Darcy's law. Therefore, to accurately simulate the conditions within a porous medium, a custom UDF function is needed to determine the formulas. This study incorporates the influence of wind speed into the top evaporation process of the 3D model. The simulation process is divided into: ① capillary water absorption process inside the 3D water delivery pipe; ② evaporation process of water vapor as it reaches the top of the liquid water computational domain for further evaporation.

[0004] This study aims to explore a visual simulation method for the long-distance water transport and evaporation process in plant xylem vessels and other directional porous media materials using numerical simulation. The xylem vessel structure determines transpiration potential. When structural factors are constant, the core factors influencing plant water transpiration are soil water supply conditions, which determine transpiration levels, and meteorological conditions, which determine transpiration dynamics. The purpose of this model is to investigate the influence of environmental factors, such as wind speed, on the long-distance water transport and evaporation process in plants. Based on this, a visual simulation method using Fluent to study the water transport and evaporation process in xylem vessels is developed. Summary of the Invention

[0005] The purpose of this invention is to solve the problems in the prior art and to propose a visualization simulation method based on Fluent for studying the water transport and evaporation process of xylem vessels.

[0006] A visualization simulation method based on Fluent for studying the water transport and evaporation process in xylem vessels includes the following steps:

[0007] The first step is to establish a three-dimensional spontaneous osmosis evaporation model using ICEM software. The spontaneous osmosis evaporation model is divided into a spontaneous dialysis process and a top evaporation process.

[0008] The model is meshed, the boundary layer is locally refined, and the mesh file is exported as the input file for the fluid computation software Fluent.

[0009] The second step involves reading the mesh file obtained in the first step using the fluid calculation software Fluent, checking the mesh, and re-meshing if there are negative volume meshes in the result; otherwise, proceed to the next step. The uniform circular pipe model reads in the mesh file, with the number of meshes between 475950 and 877950.

[0010] The third step is to configure the model in Fluent;

[0011] The fourth step is to set boundary conditions in the geometric model;

[0012] Step 5: Model initialization and calculation settings;

[0013] Step 6: Read the cloud map of water absorption height change over time and the cloud map of gaseous water volume distribution of the three-dimensional spontaneous osmosis evaporation model.

[0014] In the above-mentioned visualization simulation method for studying the long-distance water transport and evaporation process of xylem vessels based on Fluent, a rectangular evaporation computational domain is added to the spontaneous osmosis model. The spontaneous osmosis evaporation model is built on a three-dimensional circular tube model. The size of the three-dimensional circular tube model is set to a pore diameter of 20-200 μm and a height of 500-5000 μm, and it is divided into three flow channels. The layers are connected by transverse pipes, and the height of each layer is evenly distributed. The diameter of the transverse connecting pipes is 5-50 μm. The two sides of the rectangular computational domain model are the air inflow boundary and the air outflow boundary, respectively. The connection between the rectangular computational domain model and the three-dimensional circular tube model is set as the water surface boundary layer. The volume fraction of liquid is 0 and the volume fraction of gas is 1. The lower surface is the water inlet surface, set as the inlet boundary, with a liquid volume fraction of 1 and a gas volume fraction of 0.

[0015] In the above-mentioned visualization simulation method for studying the long-distance water transport and evaporation process of xylem vessels based on Fluent, the computational domain is divided into two parts in the spontaneous osmosis evaporation model settings in Fluent software. First, the spontaneous osmosis process is performed, which includes the water transport process, and after the water transport process, it rises to the evaporation computational domain. Then, the top evaporation process is performed to simulate the transport and diffusion of water vapor generated by evaporation. The ANSYS FLUENT environment variables are used for debugging, and the UDF of the evaporation rate is imported to write the program. The evaporation formula is applied to the top water surface boundary, and the water vapor mass fraction at the water surface boundary is 1. The calculation selects the non-reactive substance transport model in the general finite rate model. The boundary conditions are divided into water surface boundary conditions, left air inlet boundary, outlet boundary, and top boundary.

[0016] In the above-mentioned visualization simulation method for studying the long-distance water transport and evaporation process of xylem vessels based on Fluent, during the spontaneous infiltration process, the energy equation on the operation panel, the k-epsilon equation in the viscous model, and the gravity equation Gravity are activated in sequence. The gravitational acceleration in the Z direction is set to -9.81 m / s2, and the gravitational acceleration in the X and Y directions is 0. Then, the transient model Transient is activated, and the VOF model in the two-phase flow is activated. In the two-phase flow, air is set as the first phase, liquid water is set as the second phase, and the surface tension between the two phases of air and water is set to 0.072 N / m.

[0017] In the above-mentioned visualization simulation method based on Fluent for studying the long-distance water transport and evaporation process of xylem vessels, the following settings are made during the top evaporation process:

[0018] ① The water surface is the mass flow boundary. The global transport method is used for the evaporation model, and the evaporation rate is written as a UDF and applied to the water surface boundary. The water surface temperature is set to 30.564℃, the relative humidity of the water surface layer is 100%, and the saturated moisture content at the water surface temperature is 0-100%.

[0019] ②The air inlet boundary is the velocity inlet boundary. The wind speed gradient is written into a UDF program and applied to the inlet boundary.

[0020] ③Outlet boundary: Pressure outlet boundary, outlet gauge pressure is 0, inlet and outlet inflow temperature is 35℃, relative humidity is 20%, and the corresponding water vapor fraction is 0.01466.

[0021] ④ Top surface boundary: The gradient changes of all quantities on the top surface are 0, indicating a symmetrical boundary.

[0022] In the above-mentioned visualization simulation method for studying the long-distance water transport and evaporation process of xylem vessels based on Fluent, the boundary conditions and calculation methods in the geometric model include: setting the solid wall of the three-dimensional geometric model, setting all outlet boundary conditions to pressure outlet, and setting the operating pressure to one standard atmosphere; the specific software operation is as follows: in Species Model, select Species Transport model, set water-liquid to phase-1 in the gas-liquid two-phase system; in Options, select Diffusion Energy Source; edit materials, create a name named mixture-temlate and a mixture type named mixture in Creat / Edit Materials; select incompressible-ideal-gas for Density (kg / m3); select Mixing-law for Cp (Specific Heat) (j / kg-k); select constant 0.0454 for Thermal Conductivity (w / mk); select constant 1.72e-05 for Viscosity (kg- / ms); and Mass... For Diffusivity (m² / s), select constant-dilute-appx2.88e-05; for the aqueous phase, select piecewise-polynomial for Cp (Specific Heat) (j / kg-k); for Molecular Weight (kg / kmol), select constant 18.01534; for Reference Temperature (k), select constant 298.15; for the gas phase, select constant 1006.43 for Cp (Specific Heat) (j / kg-k); for Molecular Weight (kg / kmol), select constant 28.966; for Standard State Entalpy (j / kgmol), select constant 0; for Reference Temperature (k), select constant 298.15.

[0023] In the above-mentioned visualization simulation method for studying the long-distance water transport and evaporation process of xylem vessels based on Fluent, the parameters of the computational domain are initialized during model initialization and calculation settings, and global patching is performed before running the calculation. Fluent's calculation activity options are set to automatically save .dat files, meaning that a .dat file is automatically saved to the storage location after each calculation of 5 time steps. Before calculation, the average height of the liquid water surface is set as the monitoring variable, and Report Files are added and saved to a specific storage location: Report-def-0-rflie is saved as the average water absorption height data of liquid water at each time step, and Report-def-1-rflie is saved as the volume fraction of gaseous water at each time step. The time step is set to 5.0 x 10⁻⁸ s - 1.0 x 10⁻⁷ s; the number of steps is set to 5000-50000, and the maximum number of iterations within each time step is set to 5000-10000. Finally, the calculation begins.

[0024] Compared with existing technologies, the advantages of this invention are:

[0025] (1) Fluent software can effectively simplify the long-distance water transport and top evaporation processes of xylem plants and visualize them using volume distribution cloud maps. As the water transport-evaporation process proceeds, the liquid water column below the pipe is a concave liquid surface with varying degrees of curvature. The net external force on the water column is vertically upward. Under the pull of capillary attraction, the negative pressure generated by overall evaporation, and the cohesive force of the water, the water flow in the computational domain overcomes the gravity of the water column and the viscous resistance of the wall to continuously climb upward. As the water column rises, the evaporation process in the cloud map becomes increasingly prominent, the volume fraction of gaseous water in the evaporation domain continuously increases, and the upward pulling force generated by evaporation continuously increases.

[0026] (2) By applying the wind speed gradient as a UDF to the inlet boundary, significant liquid water evaporation was observed at the top. In the water volume distribution cloud map, the volume fraction of gaseous water increased with the increase of the calculation iteration time step, and the cloud map intuitively showed the positive promoting effect of the environmental factor wind speed on evaporation. This method can study the influence of environmental factors such as wind speed on the long-distance water transport and evaporation process of plant xylem vessels, which is of great significance for further improving the spontaneous infiltration rate of porous media and developing new models of porous media. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the simulation calculation process of the present invention;

[0028] Figure 2 This is a technical roadmap of the environmental factor-regulated evaporation system of the present invention;

[0029] Figure 3This invention relates to the effect of wind speed on evaporation at different iteration time steps.

[0030] Figure 4 This invention provides a visualization cloud map of the simulated evaporation-driven water absorption process.

[0031] Figure 5 This is an overall evaporation cloud map at different time steps in the simplified single-tube model of this invention; Detailed Implementation

[0032] Reference Figure 1-5 A visualization simulation method based on Fluent for studying the water transport and evaporation process of xylem vessels includes the following steps:

[0033] The first step is to establish a spontaneous evaporation model using ICEM software. Based on the spontaneous evaporation model of a three-dimensional circular tube, a rectangular evaporation computational domain is added. The dimensions of the three-dimensional circular tube model are: aperture 20-200µm, height 500-5000µm, divided into three flow channels, connected by transverse pipes. Each layer has an even height, and the transverse connecting pipes have a diameter of 5-50µm. The upper rectangular computational domain model has air inflow and air outflow boundaries on both sides, respectively. The connection point between the rectangular computational domain model and the three-dimensional circular tube model is set as the water surface boundary layer. The liquid volume fraction is 0, and the gas volume fraction is 1. The lower surface is the inlet surface, set as the inlet boundary, with a liquid volume fraction of 1 and a gas volume fraction of 0. The geometric model is meshed, with local refinement of the boundary layers, and the mesh file is exported as the input file for the fluid computation software Fluent.

[0034] The second step involves reading the mesh file obtained in the first step using the fluid calculation software Fluent, checking the mesh, and re-meshing if there are negative volume meshes in the result; otherwise, proceed to the next step. The uniform circular pipe model reads in the mesh file, with the number of meshes between 475950 and 877950.

[0035] The third step involves setting up the model in Fluent, where the computational domain is divided into two parts. First, the water transport process is simulated. After the water rises to the evaporation computational domain, top evaporation is then implemented. The transport and diffusion of the water vapor generated by evaporation are simulated. The macroscopic mass control equation for the flow of incompressible liquid in a solid porous medium is as follows:

[0036]

[0037] For the top evaporation process, the last term of its continuity equation is the mass transfer caused by the phase transition:

[0038]

[0039] A distinct phase interface is maintained during the water conveyance process, arising from the flow of two immiscible fluids (liquid water and air). Considering the two-phase flow in the water conveyance computational domain, the two-phase flow in the pores at the microscale can be simulated by solving the Navier-Stokes equations and the interface tracking equations. The continuity equation and momentum conservation are as follows:

[0040]

[0041]

[0042]

[0043] ρ is the fluid density, u is the fluid velocity component in the x-direction, v is the fluid velocity component in the y-direction, P is the pressure, and μ is the viscosity. Sx and Sy are source terms, which include contributions from gravity and surface tension. Boundary conditions: The interface is considered a free surface under constant pressure (which changes due to variations in surface curvature and other stresses).

[0044] The continuity equation and Navier-Stokes equation for calculating the simulated flow are as follows:

[0045]

[0046]

[0047] here For local pressure gradient, Let be the point velocity, and μ be the fluid viscosity. Since the flow in the xylem of plants is laminar, we set the Reynolds number in the xylem-like porous medium to be less than or equal to 1. Under this flow condition, the inertial term in the Navier-Stokes equations can be neglected, resulting in the Stokes equations representing the momentum balance:

[0048]

[0049] In this microscopic flow context, Darcy's law can be applied to amplified flows through directional porous computational domains:

[0050]

[0051] in, The volume average flow rate; <px i Let be the average pore pressure; K be the permeability of the porous medium. For the top evaporation process, the total transport method is chosen to calculate the latent heat exchange at the water surface. The formula for the water evaporation rate is:

[0052] E = ρ a K E μ(qs -q a )

[0053] Using ANSYS FLUENT environment variables for debugging, a program was written by importing the evaporation rate UDF and applying the evaporation formula to the top water surface boundary, where the water vapor mass fraction at the water surface boundary is 1. The calculation selected the non-reactive substance transport model in the general finite rate model, with boundary conditions including water surface boundary conditions, left-side air inlet and outlet boundaries, and the top surface boundary. Specific parameters of the VOF model options in Fluent were set: the contact angle between the two phases defined in the momentum part was changed, setting the contact angle to 0°-180° in the same geometric model, using air and water as media, and setting the wall roughness KS to 0 (smooth)-0.5 in the same pipe model.

[0054] For the first stage of spontaneous absorption process, the energy equation on the operation panel, the k-epsilon (2eqn) equation in the viscous model, and the gravity equation Gravity are activated in sequence. The gravitational acceleration in the Z direction is set to -9.81m / s2, and the gravitational acceleration in the X and Y directions is 0. The transient model Transient is activated, and the VOF model in the two-phase flow is activated. In the two-phase flow, air is set as the first phase, liquid water is set as the second phase, and the surface tension between the two phases of air and water is set to 0.072N / m.

[0055] For the second-stage top evaporation process, the following settings were implemented: ① The water surface was the mass flow boundary. The evaporation model used the global transport method, and the evaporation rate was programmed into a UDF and applied to the water surface boundary. The water surface temperature was set to 30.564℃, the relative humidity of the water surface layer was 100%, and the saturated moisture content at the water surface temperature was 0-100%. ② The air inlet boundary was the velocity inlet boundary. The wind speed gradient was programmed into a UDF and applied to the inlet boundary. ③ The outlet boundary was a pressure outlet boundary, with the outlet gauge pressure set to 0. The inlet and outlet inflow temperatures were 35℃, the relative humidity was 20%, and the corresponding water vapor fraction was 0.01466. ④ The top surface boundary was a symmetrical boundary where all gradient changes were 0. Environmental factors such as wind speed were used to regulate the evaporation system. Figure 2 As shown.

[0056] Fourth, set boundary conditions in the geometric model. In the geometric model, set the solid wall of the 3D geometric model, and set all outlet boundary conditions to pressure outlet, with the operating pressure set to one standard atmosphere. Specifically: In Species Model, select the Species Transport model; in the gas-liquid two-phase configuration, set water-liquid to phase-1; in Options, select Diffusion Energy Source; edit the material; in Create / Edit Materials, create a name named mixture-temlate, and Mixture Type named mixture; Density (kg / m3) selected incompressible-ideal-gas; Cp (Specific Heat) (j / kg-k) selected Mixing-law; Thermal Conductivity (w / mk) selected constant 0.0454; Viscosity (kg- / ms) selected constant 1.72e-05; Mass... For Diffusivity (m² / s), select constant-dilute-appx2.88e-05; for the aqueous phase, select piecewise-polynomial for Cp (Specific Heat) (j / kg-k); for Molecular Weight (kg / kmol), select constant 18.01534; for Reference Temperature (k), select constant 298.15; for the gas phase, select constant 1006.43 for Cp (Specific Heat) (j / kg-k); for Molecular Weight (kg / kmol), select constant 28.966; for Standard State Enthalpy (j / kgmol), select constant 0; for Reference Temperature (k), select constant 298.15.

[0057] Step 5: Model initialization and calculation settings

[0058] Initialize the parameters of the computational domain and perform global patching using Patch before running the calculation. In Fluent's computational activity options, set up automatic saving of .dat files. This means that Fluent automatically saves one .dat file to the storage location each time it completes a calculation of 5 time steps. Before the calculation, set the average height of the liquid water surface as the monitoring variable and add Report Files to save to a specific storage location: Report-def-0-rflie saves the average water absorption height data of the liquid water at each time step, and Report-def-1-rflie saves the volume fraction of gaseous water at each time step. Set the time step to 5.0 x 10⁻⁸ s - 1.0 x 10⁻⁷ s; set the number of steps to 5000-50000; and set the maximum number of iterations within each time step to 5000-10000. Start the calculation.

[0059] Step 6: Analyze the effect of wind speed on evaporation at different iteration time steps in the spontaneous percolation evaporation model, such as... Figure 3 As shown, the cloud map of water absorption height changing over time and the cloud map of gaseous water volume distribution in the spontaneous osmotic evaporation model are read. The visualization cloud map simulating the water absorption process driven by evaporation is shown below. Figure 4 As shown, the top is a cuboid evaporation computational domain. Besides capillary traction, the negative pressure generated by evaporation is also a driving force for the liquid water to overcome its own gravity and pipe wall resistance, thus achieving the upward movement of water within the pipe. It can be seen that during the initial water rise process, the liquid surface inside the three-dimensional pipe maintains a concave curved surface to varying degrees. The resultant external force from various factors is a vertically upward traction force, with capillary attraction playing a decisive role at this stage. Until the water rises to near the top of the liquid surface, the effect of evaporation traction becomes increasingly significant, and the gravitational resistance of the liquid water column gradually increases, becoming equal to the resultant force of capillary attraction and evaporation traction. Under the influence of the wind speed at the left inlet, the curved liquid surface of the top water column gradually becomes gentler or even convex. In a further simplified single-pipe model, the visualization of the overall evaporation at different time steps is shown below. Figure 5 As shown, the volume fraction distribution of liquid water in a single tube evaporation is compared at different iteration time steps, using 10,000 time steps as the unit. The coordinates of the left-hand cloud map represent the volume fraction of gaseous water. The blue area at the bottom of the cloud map indicates that the water column continues to rise, while the area closer to the red cloud map indicates a higher volume fraction of gaseous water vapor inside the channel.

[0060] In summary, this invention provides a visualization simulation method based on Fluent for studying the long-distance water transport and evaporation process of plant xylem vessels. This method combines the modeling software ICEM and the computational fluid dynamics software Fluent, simplifying the plant xylem vessels into a uniform three-dimensional cylindrical pipe with transversely connected perforated flow channels. The long-distance water transport and top evaporation process of the plant xylem vessels is divided into two steps: the capillary water absorption process inside the three-dimensional water transport pipe and the evaporation process of the liquid water in the computational domain as it approaches the top for further evaporation. During the top evaporation process, the influence of the environmental factor wind speed variable on the water transport and evaporation process of this model is investigated.

[0061] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative and not exhaustive. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A visualization simulation method based on Fluent for studying the long-distance water transport and evaporation process of xylem vessels, characterized in that, Includes the following steps: The first step is to establish a three-dimensional spontaneous osmosis evaporation model using ICEM software. The spontaneous osmosis evaporation model is divided into a spontaneous dialysis process and a top evaporation process. The model is meshed, the boundary layer is locally refined, and the mesh file is exported as the input file for the fluid computation software Fluent. The second step is to read the mesh file obtained in the first step using the fluid calculation software Fluent, check the mesh, and if there are negative volume meshes in the results, re-mesh the mesh. If there is no negative volume mesh in the result, proceed to the next step, in which the uniform circular tube model reads in the mesh file, and the number of meshes is between 475950 and 877950; The third step is to configure the model in Fluent; The fourth step is to set boundary conditions in the geometric model; Step 5: Model initialization and calculation settings; Step 6: Read the cloud map of water absorption height change over time and the cloud map of gaseous water volume distribution of the three-dimensional spontaneous osmosis evaporation model.

2. The visualization simulation method for studying the water transport and evaporation process of xylem vessels based on Fluent according to claim 1, characterized in that: Based on the spontaneous osmosis model, a rectangular evaporation computational domain is added. The spontaneous osmosis evaporation model is built on a three-dimensional circular tube model. The dimensions of the three-dimensional circular tube model are set to a pore diameter of 20-200 μm and a height of 500-5000 μm, and it is divided into three flow channels. The layers are connected by transverse pipes, and the height of each layer is evenly distributed. The diameter of the transverse connecting pipes is 5-50 μm. The two sides of the rectangular computational domain model are the air inflow boundary and the air outflow boundary, respectively. The connection between the rectangular computational domain model and the three-dimensional circular tube model is set as the water surface boundary layer. The volume fraction of liquid is 0, and the volume fraction of gas is 1. The lower surface is the water inlet surface, set as the inlet boundary, with a liquid volume fraction of 1 and a gas volume fraction of 0.

3. The visualization simulation method for studying the water transport and evaporation process of xylem vessels based on Fluent according to claim 1, characterized in that: In the spontaneous osmosis evaporation model settings in Fluent software, the computational domain is divided into two parts. First, the spontaneous osmosis process is performed, which includes the water transport process. After the water transport process, the water rises to the evaporation computational domain. Then, the top evaporation process is performed to simulate the transport and diffusion of water vapor generated by evaporation. The ANSYS FLUENT environment variables are used for debugging. The UDF of the evaporation rate is imported and the program is written. The evaporation formula is applied to the top water surface boundary. The water vapor mass fraction at the water surface boundary is 1. The calculation selects the non-reactive substance transport model in the general finite rate model. The boundary conditions are divided into water surface boundary conditions, left air inlet boundary, outlet boundary, and top boundary.

4. The visualization simulation method for studying the water transport and evaporation process of xylem vessels based on Fluent according to claim 1, characterized in that: During the spontaneous infiltration process, the energy equation on the operation panel, the k-epsilon equation in the viscous model, and the gravity equation Gravity are activated in sequence. The gravitational acceleration in the Z direction is set to -9.81 m / s², and the gravitational acceleration in the X and Y directions is set to 0. Then, the transient model Transient is activated, and the VOF model in the two-phase flow is activated. In the two-phase flow, air is set as the first phase, liquid water is set as the second phase, and the surface tension between the two phases of air and water is set to 0.072 N / m.

5. The visualization simulation method for studying the water transport and evaporation process of xylem vessels based on Fluent according to claim 1, characterized in that: During the top evaporation process, the following are respectively set: ① The water surface is the mass flow boundary. The global transport method is used for the evaporation model, and the evaporation rate is written as a UDF and applied to the water surface boundary. The water surface temperature is set to 30.564℃, the relative humidity of the water surface layer is 100%, and the saturated moisture content at the water surface temperature is 0-100%. ②The air inlet boundary is the velocity inlet boundary. The wind speed gradient is written into a UDF program and applied to the inlet boundary. ③Outlet boundary: Pressure outlet boundary, outlet gauge pressure is 0, inlet and outlet inflow temperature is 35℃, relative humidity is 20%, and the corresponding water vapor fraction is 0.01466. ④ Top surface boundary: The gradient changes of all quantities on the top surface are 0, indicating a symmetrical boundary.

6. The visualization simulation method for studying the water transport and evaporation process of xylem vessels based on Fluent according to claim 1, characterized in that: Setting boundary conditions and their calculation methods in the geometric model includes: setting the solid wall of the three-dimensional geometric model, setting all outlet boundary conditions to pressure outlet, and setting the operating pressure to one standard atmosphere; the specific software operation is as follows: in Species Model, select the Species Transport model, set the water-liquid phase to phase-1 in the gas-liquid two-phase configuration; select Diffusion Energy Source in Options; edit the material, create a name named mixture-temlate and a mixture type named mixture in Creat / EditMaterials; select incompressible-ideal-gas for Density (kg / m3); select Mixing-law for Cp (Specific Heat) (j / kg-k); select constant 0.0454 for Thermal Conductivity (w / mk); select constant 1.72e-05 for Viscosity (kg- / ms); select constant-dilute-appx 2.88e-05 for Mass Diffusivity (m2 / s); set Cp (Specific For Heat (j / kg-k), select piecewise-polynomial; for Molecular Weight (kg / kmol), select constant 18.01534; for Reference Temperature (k), select constant 298.15; for Gas Phase Settings Cp (Specific Heat) (j / kg-k), select constant 1006.43; for Molecular Weight (kg / kmol), select constant 28.966; for Standard State Enthalpy (j / kgmol), select constant 0; for Reference Temperature (k), select constant 298.

15.

7. The visualization simulation method for studying the water transport and evaporation process of xylem vessels based on Fluent according to claim 1, characterized in that: In model initialization and computation settings, the parameters of the computational domain are initialized, and global patching is performed using Patch before running the computation. Fluent's computation activity options are set to automatically save .dat files, meaning that a .dat file is automatically saved to the storage location after each 5 time-step computation. Before computation, the average height of the liquid water surface is set as the monitoring variable, and Report Files are added and saved to a specific storage location: Report-def-0-rflie is saved as the average water absorption height data of liquid water at each time step, and Report-def-1-rflie is saved as the volume fraction of gaseous water at each time step. The time step is set to 5.0 x 10⁻⁸ s - 1.0 x 10⁻⁷ s; the number of steps is set to 5000-50000, and the maximum number of iterations within each time step is set to 5000-10000. Finally, the computation begins.

Images