Hydrodynamic-chemical crystallization coupling numerical simulation method and system based on level set

Abstract

The present invention discloses a hydrodynamic-chemical crystallization coupling numerical simulation method and system based on level set, which is used to simulate the karst water crystallization blockage process of tunnel drainage pipes in karst areas. The model can break through the numerical quantification method of the limitations of empirical formula parameters and the traditional DBL theoretical model that only considers the limitations of homogeneous flow systems, and attempts to establish a multi-field coupled hydrodynamic-chemical reaction coupling model to simulate the crystallization blockage process of karst tunnel drainage pipes. The method provided by the present invention includes: constructing a drainage pipe karst water crystallization blockage model that considers the coupling of pipeline hydrodynamic field, concentration field and chemical reaction field, while considering the process of drainage pipe crystallization blockage under the combined action of temperature, ion concentration and flow rate, characterizing the moving boundary displacement based on the level set method, and then carrying out the numerical simulation of crystallization blockage of karst tunnel drainage pipes. The simulation technology provided by the present invention can provide technical support for early identification and safety evaluation of karst tunnel blockage.

Description

Technical Field

[0001] The invention relates to a hydrodynamic-chemical crystallization coupling numerical simulation method and system based on level sets, belonging to the technical field of hydrology and water resources. Background Art

[0002] In recent years, my country has built a large number of tunnel projects in karst areas. The hydrogeological conditions in karst areas are complex, and tunnel seepage and water gushing disasters are frequent. Tunnel construction often requires a supporting drainage system. However, in the actual production process, there is a lack of numerical simulation technology to systematically study the dynamic process prediction and precise control technology of tunnel drainage pipe crystallization blockage. The key scientific issue of drainage pipe crystallization blockage is to study the hydrodynamic characteristics and reactive solute migration process in the karst system in the drainage pipe. Since the crystallization blockage process is a complex fluid migration and chemical reaction coupling process between ions in karst groundwater, it is an extremely complex nonlinear reactive solute migration system, including the seepage dynamic field in rock pores during karst groundwater seepage, the solute diffusion field in low permeability heterogeneous media, the water-rock interaction between karst groundwater and rock minerals, and the reactive chemical dynamic field generated by the dissolution-precipitation process of soluble salt components.

[0003] Studying the complex coupling process of fluid migration and geochemical reactions during crystal blockage and then constructing a three-dimensional karst tunnel drainage system and reactive solute migration is the key technical means to accurately characterize the dissolution-precipitation process during crystal blockage, and it is also the basis for achieving accurate quantification of crystal blockage. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a hydrodynamic-chemical crystallization coupling numerical simulation method and system based on level sets. First, a reactive solute transport model suitable for tunnel drainage pipes in karst areas is constructed, and the CaCO3 dissolution-precipitation process under the combined effects of temperature, flow rate and concentration is considered. Then, it is applied to simulate the complex nonlinear reaction system of multi-field coupling of seepage-diffusion-chemical reaction in the process of drainage pipe crystallization blockage. This invention not only needs to consider the complexity of independent processes, but also solves the coupling relationship between the processes, and then realizes the accurate simulation and dynamic regulation of the drainage pipe crystallization blockage process based on level sets.

[0005] The present invention specifically adopts the following technical solution: a hydrodynamic-chemical crystallization coupling numerical simulation method based on a level set, comprising the following steps:

[0006] Step SS1: Determine the model parameters of each physical field, the model parameters include: fluid density, flow velocity, fluid viscosity, turbulent kinetic energy, turbulent dissipation rate of the turbulent k-ε model, convective mass transfer coefficient, surface reaction rate constant, activation energy, saturation concentration of the chemical reaction model, level set variable, fluid velocity, reinitialization parameter, interface thickness control parameter of the level set model;

[0007] Step SS2: According to the model parameters collected in step SS1, the reactive solute transport equation in the drain pipe is established based on the basic principles of mass and energy conservation and the turbulence equation;

[0008] Step SS3: Determine the initial conditions, boundary conditions, hydraulic parameters, source and sink terms of the reactive solute transport model, and perform spatial grid division and time discretization;

[0009] Step SS4: Solve the reactive solute transport model to obtain the distribution of velocity vector and solute concentration in time and space in the simulation area;

[0010] Step SS5: Based on the results of the reactive solute transport model obtained in step SS4, a level set-based hydrodynamic-chemical crystallization process coupling numerical simulation model is established according to the level set equation;

[0011] Step SS6: Determine the initial conditions, boundary conditions, model parameters and source and sink items of the numerical model of drainage pipe crystallization blockage, and perform spatial grid division and time discretization;

[0012] Step SS7: Solve the numerical model of crystallization blockage of the karst tunnel drainage pipe to obtain the distribution of velocity vectors and solute concentration in time and space in the modified simulation area and the volume fraction distribution of generated crystals;

[0013] Step SS8: According to the changes in flow field, concentration field and volume fraction of crystals, the change trend of the sedimentary layer interface is depicted to complete the numerical simulation of crystallization blockage in the karst tunnel.

[0014] As a preferred embodiment, the reactive solute transport model in step SS4 and the drain pipe crystallization blockage numerical model in step SS7 both include a turbulence model and a chemical reaction model.

[0015] As a preferred embodiment, the turbulence model in step SS4 is calculated using a standard k-ε model:

[0016]

[0017] Where ρ is the fluid density, u is the flow velocity, p is the pressure, I is the turbulence intensity, K is the viscous stress, F is the volume force, μ is the fluid dynamic viscosity, and μ T is the turbulent kinematic viscosity, is the Lagrangian operator, k is the turbulent kinetic energy, and ∈ is the turbulent dissipation rate.

[0018] As a preferred embodiment, the process of establishing the chemical reaction model in step SS4 includes:

[0019] Step a: Determine the chemical reaction of the CaCO3 crystallization process:

[0020]

[0021] Step b: Establishing a thermodynamic database of equilibrium reactions to calculate the component forms of the required species and participate in the numerical simulation of reactive solute transport;

[0022] Step c: Establish the rate equation of the kinetic reaction: Determine the reaction rate equation involved in mineral dissolution and precipitation based on the chemical reaction kinetic transition state theory (TST).

[0023] As a preferred embodiment, step b specifically includes: defining the aqueous solution components and generated species during the crystallization blockage of the drain pipe, determining the generation reaction process and thermodynamic equilibrium constants of the generated species, and combining the aqueous solution components, generated species and thermodynamic equilibrium constants into a data combination, and finally combining the data of multiple components in the reactive solute transport model into an equilibrium reaction thermodynamic database.

[0024] As a preferred embodiment, the rate equation for establishing the kinetic reaction in step c specifically includes: using the CaCO3 deposition-erosion reaction rate expression:

[0025] m=m d -m r (5)

[0026]

[0027] Where m is the net deposition rate, m d is the deposition rate, m r is the erosion rate, β is the convective mass transfer coefficient, k R is the surface reaction rate constant, u is the flow rate, m f is the dirt mass per unit area, β is the linear expansion coefficient, T w 、T f are the tube wall temperature and fluid temperature, respectively, P is the crystal particle size.

[0028] As a preferred embodiment, the rate equation of the kinetic reaction in step c, the rate constant k at a temperature of 25° C. is:

[0029] k R =kR0 exp (-E / RT F ) (8)

[0030] Among them, k R , k R0 is the surface reaction rate constant, E is the activation energy, R is the molar gas constant, T F is the surface temperature of the scale layer.

[0031] As a preferred embodiment, the displacement change of the boundary of the numerical model of the drain pipe crystal blockage is solved in step SS8, and the movement of the two-phase flow interface is captured by the level set equation based on the level set method:

[0032]

[0033] Where φ is the level set variable, u is the fluid velocity, γ is the reinitialization parameter (unit: m / s), and ε is the interface thickness control parameter (unit: m). is the gradient operator.

[0034] The present invention also proposes a hydrodynamic-chemical crystallization coupling numerical simulation system based on level sets, comprising:

[0035] A model parameter determination module is used to perform: determining the model parameters of each physical field, wherein the model parameters include: fluid density, flow velocity, fluid viscosity, turbulent kinetic energy, and turbulent dissipation rate of the turbulent k-ε model, convective mass transfer coefficient, surface reaction rate constant, activation energy, and saturation concentration of the chemical reaction model, and the normal grid velocity, fluid velocity, moving boundary smoothing adjustment parameter, and surface gradient operator of the level set equation;

[0036] A reactive solute transport equation establishment module is used to execute: according to the model parameters collected by the model parameter determination module, based on the mass and energy conservation principles and the turbulence equation to establish the reactive solute transport equation in the drainage pipe;

[0037] The initial meshing and discretization module is used to perform: determine the initial conditions, boundary conditions, hydraulic parameters, source and sink terms of the reactive solute transport model, and perform spatial meshing and time discretization;

[0038] The vector concentration distribution module is used to perform: solving the reactive solute transport model to obtain the distribution of velocity vectors and solute concentration in time and space in the simulation area;

[0039] The blockage numerical model building module is used to execute: based on the reactive solute transport model results obtained by the vector concentration distribution module, according to the level set equation, a hydrodynamic-chemical crystallization process coupling numerical simulation model based on the level set is established;

[0040] The secondary dissection and discretization module is used to perform: determining the initial conditions, boundary conditions, model parameters and source and sink items of the drainage pipe crystallization blockage numerical model in the blockage numerical model establishment module, and performing spatial grid division and time discretization;

[0041] The blockage numerical model solving module is used to perform: solving the crystal blockage numerical model of the karst tunnel drainage pipe, and obtaining the distribution of the velocity vector in time and space, the distribution of the solute concentration, and the volume fraction distribution of the generated crystals in the corrected simulation area;

[0042] The module of sediment interface change trend is specifically implemented as follows: according to the changes in flow field, concentration field and volume fraction of crystals, the displacement changes of the boundary of the numerical model of crystal blockage of the drainage pipe are depicted, and the numerical simulation of crystal blockage of the karst tunnel is completed.

[0043] As a preferred embodiment, the vector concentration distribution module and the blockage numerical model solution module adopt the CFD module, chemical reaction module and level set model Level Set in the simulation software COMSOL for solution.

[0044] The beneficial effects achieved by the present invention are as follows: the hydrodynamic-chemical crystallization coupling numerical simulation method and system based on level sets can realize the coupling process of hydrodynamic-chemical reactions of crystallization blockage in karst tunnel drainage pipes, improve the numerical simulation capability of drainage pipe reaction migration, realize precise control and dynamic regulation of the crystallization blockage process in drainage pipes, and provide technical support for the sustainable utilization of karst tunnel drainage systems and early identification and safety evaluation of karst tunnel blockages. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of the numerical simulation method for crystallization blockage of karst tunnel drainage pipes;

[0046] Figure 2 It is a three-dimensional schematic diagram of the conceptual model of the karst tunnel drainage pipe;

[0047] Figure 3 It is a cross-sectional schematic diagram of the conceptual model of the karst tunnel drainage pipe;

[0048] Figure 4 This is a diagram of the interface changes of CaCO3 crystal deposition in the drainage pipe;

[0049] Figure 5 It is a graph showing the change in the CaCO3 deposition / erosion rate;

[0050] Figure 6 It is the result of the change of CaCO3 crystallization rate under different temperature conditions;

[0051] Figure 7 It is the result of the change of CaCO3 crystallization rate under different flow rate conditions;

[0052] Figure 8 It is the result of the change in the crystallization rate of CaCO3 under different concentration conditions. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0054] Embodiment 1: The present invention proposes a hydrodynamic-chemical crystallization coupling numerical simulation system based on level sets, comprising:

[0055] A model parameter determination module is used to perform: determining the model parameters of each physical field, wherein the model parameters include: fluid density, flow velocity, fluid viscosity, turbulent kinetic energy, and turbulent dissipation rate of the turbulent k-ε model, convective mass transfer coefficient, surface reaction rate constant, activation energy, and saturation concentration of the chemical reaction model, and the normal grid velocity, fluid velocity, moving boundary smoothing adjustment parameter, and surface gradient operator of the level set equation;

[0056] A reactive solute transport equation establishment module is used to execute: according to the model parameters collected by the model parameter determination module, based on the mass and energy conservation principles and the turbulence equation to establish the reactive solute transport equation in the drainage pipe;

[0057] The initial meshing and discretization module is used to perform: determine the initial conditions, boundary conditions, hydraulic parameters, source and sink terms of the reactive solute transport model, and perform spatial meshing and time discretization;

[0058] The vector concentration distribution module is used to perform: solving the reactive solute transport model to obtain the distribution of velocity vectors and solute concentration in time and space in the simulation area;

[0059] The blockage numerical model building module is used to execute: based on the reactive solute transport model results obtained by the vector concentration distribution module, according to the level set equation, a hydrodynamic-chemical crystallization process coupling numerical simulation model based on the level set is established;

[0060] The secondary dissection and discretization module is used to perform: determining the initial conditions, boundary conditions, model parameters and source and sink items of the drainage pipe crystallization blockage numerical model in the blockage numerical model establishment module, and performing spatial grid division and time discretization;

[0061] The blockage numerical model solving module is used to perform: solving the crystal blockage numerical model of the karst tunnel drainage pipe, and obtaining the distribution of the velocity vector in time and space, the distribution of the solute concentration, and the volume fraction distribution of the generated crystals in the corrected simulation area;

[0062] The module of sediment interface change trend is specifically implemented as follows: according to the changes in flow field, concentration field and volume fraction of crystals, the displacement changes of the boundary of the numerical model of crystal blockage of the drainage pipe are depicted, and the numerical simulation of crystal blockage of the karst tunnel is completed.

[0063] As a preferred embodiment, the vector concentration distribution module and the blockage numerical model solution module adopt the CFD module, chemical reaction module and level set model Level Set in the simulation software COMSOL for solution.

[0064] Embodiment 2: The present invention provides a hydrodynamic-chemical crystallization coupling numerical simulation system based on level sets. The embodiment of the present invention takes the established ideal model of karst tunnel drainage management as an example.

[0065] 1) Conceptual model of karst tunnel drainage pipe

[0066] Based on the indoor test design in the literature survey, a conceptual model of the sewer pipe with the same physical parameters and hydraulic characteristics as in the actual scenario was established. Figure 2 As shown, the left end is the inflow boundary and the right end is the outflow boundary. The main physical parameters are shown in Table 1. The length of the drainage pipe is 0.3m and the pipe diameter is 0.02m. The left side is set as the given flow rate inflow boundary and the right side is the free outflow boundary. In addition, the left boundary is the given concentration boundary and the right side is the free outflow boundary. Other hydrodynamic and hydrochemical parameters in the model are shown in Table 2. The simulation duration is 100d, and the time discretization is set with a given time step Δt=1d. The chemical components in the simulation process include H2O, Ca 2+ Mg 2+ , H + 、HCO-3、CO3 2- And related aqueous complexes, the mineral components are mainly calcite, dolomite, quartz, albite, potassium feldspar, muscovite, etc.

[0067] Table 1 Main physical parameters of the conceptual model in the embodiment of the invention

[0068]

[0069]

[0070] Table 2 Hydrodynamic and hydrochemical parameters of drainage pipes

[0071]

[0072] 2) Chemical reaction system during crystallization blockage

[0073] High concentration of karst groundwater flows into the drainage pipes, Ca 2+ Mg 2+ 、CO3 2- 、HCO3- , CO2, H2O and other ions jointly participate in the reaction process in the system, which mainly involves the dissolution-precipitation process of CaCO3.

[0074] The dissolution and precipitation of minerals are controlled by thermodynamic equilibrium. The dissolution or precipitation state of minerals is judged by the mineral saturation index (SI). The mineral saturation index SI is expressed by the following formula:

[0075]

[0076] Where SI is the saturation index, IAP is the ion activity product, K sp is the solubility product constant. If SI<0, it means that the mineral has not reached saturation; if SI=0, it means that the mineral has not reached saturation; if SI>0, it means that the mineral has precipitated.

[0077] The mineral dissolution and precipitation controlled by reaction kinetics is represented by the mineral reaction rate. The composition of the participating minerals in the model and the calculation parameters of the mineral reaction kinetic rate are shown in Table 3.

[0078] Table 3 Calculation parameters of mineral reaction kinetic rates

[0079]

[0080]

[0081] Note: The superscripts a and b represent the dissolution of minerals under the neutral mechanism (spontaneous) and the dissolution under the acidic mechanism, respectively.

[0082] 3) Determine the control equation

[0083] A) The flow field is calculated using the standard k-ε turbulence model, and the governing equation is in the form of:

[0084]

[0085] Where ρ is the fluid density, u is the flow velocity, p is the pressure, I is the turbulence intensity, K is the viscous stress, F is the volume force, μ is the fluid dynamic viscosity, and μ T is the turbulent kinematic viscosity, is the Lagrangian operator, k is the turbulent kinetic energy, and ∈ is the turbulent dissipation rate.

[0086] B) The standard convection-dispersion equation is used to solve the concentration field. The governing equation is in the form of:

[0087]

[0088]

[0089] In the formula, J jis the diffusion flux, c j is the concentration at node j, u is the flow rate, R j is the source-sink term, D j is the diffusion coefficient.

[0090] C) The net deposition rate model proposed by Kern and Seaton (i.e., deposition rate minus erosion rate) is used to solve the chemical reaction field.

[0091] m=m d -m r (7)

[0092] a) Using the ion diffusion model proposed by Hasson et al.:

[0093]

[0094] k R =k R0 exp (-E / RT F ) (9)

[0095] Where m d is the deposition rate, β is the convective mass transfer coefficient, k R , k R0 is the surface reaction rate constant, c f 、c s are the concentration of CaCO3 in the tube and the saturated concentration of CaCO3, E is the activation energy, R is the molar gas constant, T F is the surface temperature of the scale layer.

[0096] b) Using the model proposed by Bohnet:

[0097]

[0098] Where m r is the erosion rate, u is the flow velocity, m f is the dirt mass per unit area, β is the linear expansion coefficient, T w 、T f are the tube wall temperature and fluid temperature, respectively, P is the crystal particle size.

[0099] 4) Establishing the level set model

[0100] Based on the level set method, the motion of the two-phase flow interface is captured by the level set equation:

[0101] Where φ is the level set variable, u is the fluid velocity, γ is the reinitialization parameter (unit: m / s), ε is the interface thickness control parameter (unit: m), is the gradient operator.

[0102] 5) Analysis of simulation results of crystallization blockage of karst tunnel drainage pipes

[0103] Figure 3 The graph of the deposition interface of the CaCO3 crystal layer in the tunnel drainage pipe changes with time. The change of the calcium carbonate crystal deposition interface is consistent with the change of the calcium carbonate concentration field. The higher the CaCO3 concentration, the faster the crystal deposition speed. From 0-100d, as the crystallization process continues, the thickness of the crystal layer attached to the pipe wall gradually increases, and Figure 6 It can be seen that the deposition interface shows obvious uneven changes. At the same time, the thickness of the deposition layer in the outlet section is greater than that in the inlet section.

[0104] Figure 4 and Figure 5 The graph shows the change of CaCO3 deposition, erosion and net deposition rate over time (0-100d). Figure 4 It can be seen that as the CaCO3 crystallization process continues, the deposition rate decreases but the change is not large; while the erosion rate changes significantly. In the early stage of the crystallization process, the erosion rate increases from nearly 0 to 2×10 - 7 kg / (m 2 ·s), the change range is large, and then it maintains a relatively stable growth. In the early stage, with the formation of the crystal layer, the effective flow area of ​​the pipeline decreases, causing the flow velocity to increase, the shear force of the fluid on the crystal layer to increase, and the erosion rate gradually increases. When the CaCO3 grains begin to adhere to the inner wall of the pipeline, their grain size is still small, and the adhesion to the pipe wall is relatively weak. They are easily hit by water molecules and detached from the wall. Only when the grain size is large, the adhesion between the grain and the wall can be stably adsorbed on the wall. Although the erosion rate gradually increases at this stage, it is caused by Figure 5 It can be seen that it is always less than the deposition rate of CaCO3. According to the calculation formula of the net deposition rate, it can be seen that although the net deposition rate gradually decreases, it is always positive, indicating that within 0-100 days, the crystallization deposition process in the drainage pipe is constantly ongoing, and a large amount of CaCO3 generated in the fluid is crystallized and precipitated. From the curve of the deposition rate and the erosion rate, it can be inferred that when the time scale is long enough, if the drainage pipe is not completely blocked at the end of the stress period, the deposition rate and the erosion rate will tend to be equal. At this time, the net deposition rate is 0, and the crystallization process of CaCO3 no longer occurs in the pipe, and the blockage degree of the drainage pipe reaches a maximum value.

[0105] Figure 6-8The figure shows the trend of the crystallization rate when the temperature, inlet flow rate and inflow concentration are changed. It can be seen from the figure that when the temperature, inlet flow rate and ion inflow concentration are changed, the crystallization rate of CaCO3 will change significantly. When the temperature increases from 283.15K to 303.15K, the value of the crystallization rate of CaCO3 after the amplitude stabilizes increases from nearly 0 to 5×10 -7 kg / (m 2 ·s), indicating that the crystallization rate of CaCO3 in the drainage pipe is positively correlated with the temperature; when the inlet velocity increases from 0.5m / s to 0.9m / s, the crystallization rate value after the amplitude stabilizes increases from 2.0×10 -7 kg / (m 2 ·s) decreases to a negative value, indicating that the CaCO3 crystallization rate is negatively correlated with the inlet flow rate (it is worth noting that the negative value here is a theoretical value. In fact, when the crystallization rate is equal to 0, the deposition rate is equal to the erosion rate, and crystallization no longer occurs at this time); when the ion inflow concentration increases from 6.5 mol / m 3 Increased to 8.5 mol / m 3 When the amplitude of the CaCO3 crystallization increases to 2.0×10 -7 kg / (m 2 ·s), indicating that the crystallization rate of CaCO3 is positively correlated with the ion inflow concentration. This indicates that in the actual prevention and control of blockage in tunnel drainage systems, controlling temperature, flow rate and concentration plays an important role in the prevention and control effect.

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets, characterized in that: The steps include: Step SS1: Determine the model parameters of each physical field, the model parameters include: fluid density, flow velocity, fluid viscosity, turbulent kinetic energy, turbulent dissipation rate of the turbulent k-ε model, convective mass transfer coefficient, surface reaction rate constant, activation energy, saturation concentration of the chemical reaction model, level set variable, fluid velocity, reinitialization parameter, interface thickness control parameter of the level set model; Step SS2: According to the model parameters collected in step SS1, the reactive solute transport equation in the drain pipe is established based on the basic principles of mass and energy conservation and the turbulence equation; Step SS3: Determine the initial conditions, boundary conditions, hydraulic parameters, source and sink terms of the reactive solute transport model, and perform spatial grid division and time discretization; Step SS4: Solve the reactive solute transport model to obtain the distribution of velocity vector and solute concentration in time and space in the simulation area; Step SS5: Based on the results of the reactive solute transport model obtained in step SS4, a level set-based coupled numerical simulation model of the hydrodynamic-chemical crystallization process is established according to the level set equation; Step SS6: Determine the initial conditions, boundary conditions, model parameters and source and sink items of the numerical model of drainage pipe crystallization blockage, and perform spatial grid division and time discretization; Step SS7: Solve the numerical model of crystallization blockage of the karst tunnel drainage pipe to obtain the distribution of velocity vectors and solute concentration in time and space in the modified simulation area and the volume fraction distribution of generated crystals; Step SS8: According to the changes in flow field, concentration field and crystal volume fraction, the change trend of the sedimentary layer interface is depicted, and the numerical simulation of crystal blockage in the karst tunnel is completed; in the step SS8, the displacement change of the boundary of the numerical model of crystal blockage of the drainage pipe is solved, and the movement of the two-phase flow interface is captured by the level set equation based on the level set method: Where φ is the level set variable, u is the fluid velocity, γ is the reinitialization parameter (unit: m / s), and ε is the interface thickness control parameter (unit: m). is the gradient operator.

2. The hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets according to claim 1 is characterized in that: The reactive solute transport model in step SS4 and the drain pipe crystallization blockage numerical model in step SS7 both include a turbulence model and a chemical reaction model.

3. The hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets according to claim 2 is characterized in that: The turbulence model in step SS4 is calculated using the standard k-ε model: Where ρ is the fluid density, u is the flow velocity, p is the pressure, I is the turbulence intensity, K is the viscous stress, F is the volume force, μ is the fluid dynamic viscosity, and μ T is the turbulent kinematic viscosity, is the Lagrangian operator, k is the turbulent kinetic energy, and ∈ is the turbulent dissipation rate.

4. The hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets according to claim 2 is characterized in that: The process of establishing the chemical reaction model in step SS4 includes: Step a: Determine the chemical reaction of the CaCO3 crystallization process: Step b: Establishing a thermodynamic database of equilibrium reactions to calculate the component forms of the required species and participate in the numerical simulation of reactive solute transport; Step c: Establish the rate equation of the kinetic reaction: Determine the reaction rate equation involved in mineral dissolution and precipitation based on the chemical reaction kinetic transition state theory (TST).

5. The hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets according to claim 4 is characterized in that: The step b specifically includes: defining the components of the aqueous solution and the generated species during the crystallization blockage of the drain pipe, determining the generation reaction process and thermodynamic equilibrium constant of the generated species, and combining the components of the aqueous solution, the generated species and the thermodynamic equilibrium constant into a data combination, and finally combining the data of multiple components in the reactive solute transport model into an equilibrium reaction thermodynamic database.

6. The hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets according to claim 4 is characterized in that: The rate equation for establishing the kinetic reaction in step c specifically includes: using the CaCO3 deposition-erosion reaction rate expression: m=m d -m r (5) Where m is the net deposition rate, m d is the deposition rate, m r is the erosion rate, β is the convective mass transfer coefficient, k R is the surface reaction rate constant, u is the flow rate, m f is the dirt mass per unit area, β is the linear expansion coefficient, T w , T f are the tube wall temperature and fluid temperature, d P is the crystal particle size.

7. The hydrodynamic-chemical crystallization coupling numerical simulation method based on level sets according to claim 6 is characterized in that: The rate equation of the kinetic reaction in step c, the rate constant k at a temperature of 25° C. is: k R =k R0 exp (-E / RT F ) (8) Among them, k R , k R0 is the surface reaction rate constant, E is the activation energy, R is the molar gas constant, T F is the surface temperature of the scale layer.

8. A hydrodynamic-chemical crystallization coupled numerical simulation system based on level sets, with the following features: A model parameter determination module is used to perform: determining the model parameters of each physical field, wherein the model parameters include: fluid density, flow velocity, fluid viscosity, turbulent kinetic energy, and turbulent dissipation rate of the turbulent k-ε model, convective mass transfer coefficient, surface reaction rate constant, activation energy, and saturation concentration of the chemical reaction model, and the normal grid velocity, fluid velocity, moving boundary smoothing adjustment parameter, and surface gradient operator of the level set equation; A reactive solute transport equation establishment module is used to execute: according to the model parameters collected by the model parameter determination module, based on the mass and energy conservation principles and the turbulence equation to establish the reactive solute transport equation in the drain pipe; The initial meshing and discretization module is used to perform: determine the initial conditions, boundary conditions, hydraulic parameters, source and sink terms of the reactive solute transport model, and perform spatial meshing and time discretization; The vector concentration distribution module is used to perform: solving the reactive solute transport model to obtain the distribution of velocity vectors and solute concentration in time and space in the simulation area; The blockage numerical model building module is used to execute: based on the reactive solute transport model results obtained by the vector concentration distribution module, according to the level set equation, a hydrodynamic-chemical crystallization process coupling numerical simulation model based on the level set is established; The secondary dissection and discretization module is used to perform: determining the initial conditions, boundary conditions, model parameters and source and sink items of the drainage pipe crystallization blockage numerical model in the blockage numerical model establishment module, and performing spatial grid division and time discretization; The blockage numerical model solving module is used to perform: solving the crystal blockage numerical model of the karst tunnel drainage pipe, and obtaining the distribution of the velocity vector in time and space, the distribution of the solute concentration, and the volume fraction distribution of the generated crystals in the corrected simulation area; The module of sediment interface change trend is specifically implemented as follows: according to the changes in flow field, concentration field and volume fraction of crystals, the displacement changes of the boundary of the numerical model of crystal blockage of drainage pipes are depicted, and the numerical simulation of crystal blockage of karst tunnels is completed; the displacement changes of the boundary of the numerical model of crystal blockage of drainage pipes are solved, and the movement of the two-phase flow interface is captured by the level set equation based on the level set method: Where φ is the level set variable, u is the fluid velocity, γ is the reinitialization parameter (unit: m / s), and ε is the interface thickness control parameter (unit: m). is the gradient operator.

9. The hydrodynamic-chemical crystallization coupling numerical simulation system based on level sets according to claim 8, characterized in that: The vector concentration distribution module and the blockage numerical model solution module use CFD module, chemical reaction module and level set model Level Set to solve.

Images