3D Numerical Model Research Articles

A numerical study on autoignition of finite thick polymethyl methacrylate (PMMA) subjected to thermal radiation and forced airflow

A 2D numerical model coupling condensed and gas phases is developed to investigate autoignition of finite thick PMMA heated by radiation in forced airflow. Six sample thicknesses (1–15 mm), four heat fluxes (30–60 kW/m2), and five airflow velocities (0–1.2 m/s) are considered to examine their effects. The model is first verified by measured surface temperatures in experiments. Then three boundary layers (BL), velocity, thermal and concentration BLs, are studied based on simulation results and BL theory. BL thickness, local and surface-averaged frication coefficients, convective heat and mass transfer coefficients at solid–gas interface are estimated and compared with analytical results. Meanwhile, Damköhler numbers (Da) in non-ignition cases are calculated to reveal their impact. The results show that the model predicts measured surface temperatures well despite some divergence for thin samples due to deformation. Simulated velocities and thermal BL thicknesses agree well with analytical ones, yielding a maximum error of 33 % for concentration BL. Numerical convective heat and mass transfer coefficients match analytical ones well, whereas large discrepancy exists for friction coefficient. Two types of Da evolution, corresponding to different controlling mechanisms of non-ignition cases, separated by 6 mm sample are identified.

Modeling district heating pipelines using a hybrid dynamic thermal network approach

A novel numerical method is presented for fast and accurate simulation of the dynamic thermal behavior of buried pipelines such as those in district heating systems. The model is based on a combination of a conduction response factor method, known as the dynamic thermal network (DTN) method and a one-dimensional discretized heat transfer fluid flow model, the so-called plug flow N-continuously stirred tanks (PFST) model. This combination enables the model to effectively take into account the short timescale dynamic effects of pipelines including longitudinal dispersion of turbulent fluid and its thermal capacity and also transient ground heat transfer. The combined DTN-PFST model is validated by reference to experimental data from both the lab-scale representation of a district heating system and monitoring data from a full-scale operational system. The comparisons between simulation results and experimental data demonstrate a good level of accuracy of the proposed model in predicting the dynamic thermal behavior of pipelines. The model has also been found to be several orders of magnitude more computationally efficient than corresponding 3D numerical models. Both the accuracy and computational efficiency of the proposed model make it well-suited to the design and analysis of district heating distribution networks. The model is also expected to be well-suited to the modeling of horizontal ground heat exchange pipe systems.

Modeling and Validation of Assisted Cold Start for a PEMFC Coupled to a Thermochemical Preheater

Cold start from sub-zero temperatures poses a challenge for automotive application of polymer electrolyte fuel cells (PEMFC), as product water freezes inside the cells hereby endangering operation safety. Therefore, ice formation in the cathode pores has to be avoided by preheating of the fuel cell above sub-zero temperatures. The concepts for such assisted cold start can be divided into internal and external heating strategies [1]. Amongst the latter, especially thermochemical preheating by metal hydrides presents a compelling yet efficient technology, as the heat is provided by exothermal hydrogen absorption without consumption of additional external energy.In this work, assisted PEMFC cold start is simulated with the transient 2D numerical model for a single fuel cell thermally coupled to a thermochemical preheater via a coolant fluid developed by Gießgen and Jahnke [2]. Here, the numerical model is validated against cold start experiments of the coupled system for both cell behavior and thermal balance of the heat transfer fluid. Starting from an initial temperature of -5°C, fuel cell behavior is then studied for 300 s of open circuit voltage (OCV) followed by a current density ramp up to 0.33 A/cm² in 150 s and a subsequent constant current period up to 500 s. Model validation is done with respect to temperature and voltage evolution as well as the energy balance of the coupled system. When the cold start is unassisted, a significant voltage drop down to 0.6 V is observed to occur already at 0.22 A/cm² and thus before reaching the maximum current density by the end of the ramp. Whereas difficult to deduce from experiments, this intermediate voltage drop can be linked to massive ice formation blocking up to 87% of the cathode catalyst pores, eventually causing a significant decrease of the electrochemically active surface (ECSA). For this ECSA reduction, an exponential dependence on the ice saturation is identified, suggesting that initial ice nucleation primarily occurs on the macroporous catalyst surface, thereby blocking the nanoporous surfaces of the primary particles within. When the cold start is assisted, a preheating phase of 41 s is performed prior to the current ramp. As the metal hydride reactor effectively heats up the heat transfer fluid, the fuel cell temperature in turn raises rapidly above the freezing point in less than 20 s. Consequently, ice formation is observed to be effectively reduced to saturations of less than 1%. As a result of this assisted cold start, the voltage drop is significantly attenuated and a minimum voltage of 0.65 V is now reached for a maximum of 0.33 A/cm² only at the end of the current ramp.

An Iterative Method of Modeling Pump-Treat-Inject System with "Partial Treatment".

Pump-and-treat technologies are widely used in groundwater remediation and site cleanup. Such technologies involve pumping contaminated groundwater to the surface for treatment. Following treatment, the water is often reinjected back into the aquifer (referred to as pump-treat-inject or PTI) for potential reuse. The treatment system is often designed to remove dissolved-phase contaminants in groundwater such that water meets applicable cleanup standards (herein referred to as "full treatment"). However, in some cases, the treatment system may not effectively reduce the dissolved-phase concentrations (herein referred to as "partial treatment") for some of the contaminants present in groundwater. Modeling PTI under partial treatment conditions is challenging because contaminant concentrations in injected water depend on the pumped water concentrations and the system treatment efficiency. Essentially, the injected water concentration (a transport model input) is unknown prior to transport simulation. This study presents a novel iterative approach to modeling PTI under partial treatment scenarios, where the injected water concentration is linked to the modeled pumped water concentration. The method was developed for a complicated three-dimensional (3D) flow and transport modeling study conducted for a confidential remediation site where PTI with partial treatment was applied. However, due to the complexity of the 3D model and the confidential information of the site, a simple two-dimensional (2D) numerical model is presented to demonstrate the iterative method. The 2D model test runs and the 3D model application in a remediation site showed that the iterative simulation results quickly converged to a viable final solution.

Flameback identification and air intrusion prevention in small flow hydrogen flare stack emissions

In some hydrogen production, storage and applications, the flare stack is used as an indispensable protection system for the emission and ignition of surplus hydrogen. However, there is a risk of flameback when emissions at small flow rate. Thus, a series of studies were carried out to explore the flameback identification and air intrusion prevention in small flow emissions. In this study, a flare stack with a molecular sealing, which was 12 m in height and 100 mm in diameter, was selected as the physical object. And a 3D numerical model was established. (1) The small flow hydrogen flare stack emissions were performed when the nitrogen purge was completed, and in this study the purge was finished in 80 s (2) The flameback case of the numerical model in this paper was used along with the US Bureau of Mines experimental to verify the accuracy of the flameback limit flow theoretical model. Furthermore, the lower limit of the theoretical curve was extended from 100 mm to 1 mm by theoretical calculation. (3) In order to comprehensively consider the combined influence of turbulence and buoyancy at the flare stack outlet, we proposed a new dimensionless parameter Fd to represent the flow state by the Reynolds and Richardson numbers. Based on this, a general flameback identification criterion was proposed. (4) When the nitrogen/hydrogen ratio was within the range of 40–56 vol%, nitrogen auxiliary pressurization effectively inhibited air intrusion and the expansion of the flammable range.

Numerical Modelling and Experimental Validation of Dissimilar Aluminium 2014 and 7075-SiC Composite by Friction Stir Welding

In this study, a dissimilar AA7075+25% vol. SiC composite and AA2014 was selected to understand the effect of temperature distribution in the HAZ region with a maximum reinforcement of 25% vol. of SiC in the AA7075 matrix. The friction and slip-stick mechanism were combined in the numerical 3D model and simulated with different process parameters. The peak temperature of the dissimilar aluminium AA7075+25% vol. SiC composite and AA2014 was simulated and predicted as 860 K maximum and 728 K minimum, respectively. The experimental results were obtained in real-time FSW interfaced with a calibrated K-type thermocouple in a DAQ system. The thermocouple was placed at 15 mm, 20 mm, and 25 mm from the weld centerline to obtain experimental temperatures that were extremely close to the numerical peak temperature. The error percentage between the experimental values and simulation values ranged from 2.38% to 13.41%.

Freshwater resources around the reclaimed new land on the Eastern Hengsha Shoal in the Changjiang estuary

Reclaiming estuarine tidal flats is practiced to meet the growing demand for land. The reclaimed new land (RNL) on the Eastern Hengsha Shoal in the Changjiang Estuary is for agricultural production in Shanghai. Whether freshwater resources exist around the RNL has become a critical issue \caused by estuarine saltwater intrusion. In this study, the spatiotemporal saltwater intrusion and freshwater distribution around the RNL at different guarantee rates of river discharge using the improved 3D numerical model ECOM-si was investigated. Three water intakes on Hengsha Island and the northern edge of the RNL were set. The results showed that at different guarantee rates of river discharge during the dry season, there is a relatively sufficient suitable water intake time in the upper RNL. Nevertheless, there is a very limited suitable water intake time in the middle and lower RNL as the guarantee rate increases, especially in January and February. During the flood season, three water intakes can ensure sufficient suitable water intake time. The salinity around the RNL significantly increases under the combined effect of 50% and 95% guarantee rates with a 12 m/s northerly wind in February, resulting in a significant threat to the three water intakes. At the 50% guarantee rate, the suitable water intake times in February are 14.86, 9.78 and 3.53 days at three water intakes, respectively. At the 95% guarantee rate, the suitable water intake time in February is only 0.31 days in the upper RNL, and there is no freshwater in the middle and lower RNL. Overall, there is sufficient freshwater in the flood season and limited freshwater in the dry season for agriculture along the northern edge of the RNL.

The Transient Cooling Performance of a Compact Thin-Film Thermoelectric Cooler with Horizontal Structure

Thermoelectric cooling is an ideal solution for chip heat dissipation due to its characteristics of no refrigerant, no vibration, no moving parts, and easy integration. Compared with a traditional thermoelectric device, a thin-film thermoelectric device significantly improves the cooling density and has tremendous advantages in the temperature control of electronic devices with high-power pulses. In this paper, the transient cooling performance of a compact thin-film thermoelectric cooler with a horizontal structure was studied. A 3D multi-physics field numerical model with the Thomson effect considered was established. And the effects of impulse current, thermoelectric leg length, pulse current imposition time, and the size of the contact thermal resistance on the cooling performance of the device were comprehensively investigated. The results showed that the model achieved an active cooling temperature difference of 25.85 K when an impulse current of 0.26 A was imposed. The longer the length of the thermoelectric leg was, the more unfavorable it was to the chip heat dissipation. Due to the small contact area between different sections of the device, the effect of contact thermal resistance on the cooling performance of the device was moderate.

Three-dimensional concentration-polarization modeling of trace-ions in reverse osmosis

Concentration polarization (CP) is mostly evaluated through one-dimensional (1D) film models considering convective and diffusive transport of solutes. However, in multicomponent ionic solutions, electromigration and chemical speciation may also play a role in the solute transport within the CP layer, thus affecting the process performance. We developed a three-dimensional (3D) numerical model for evaluating the CP in spacer-filled feed reverse osmosis (RO) channels by coupling hydrodynamics with the transport of solutes by convection, diffusion and electromigration, and chemical speciation by several ion-pairing equilibria. A realistic spacer geometry was obtained by CT-scans of commercial RO spacers. The model revealed highly non-uniform distributions of CP, mass transfer coefficients and precipitation potential on the membrane. While electromigration tends to equalize the fluxes of dominant ions, increases locally the CP of anions and decreases that of cations, it was found not to significantly affect the boundary layer thickness. However, the chemical speciation strongly affected the CP of trace ions binding with dominant ions. Finally, the 3D results were compared with those obtained from simpler 1D models. While 1D approaches help explaining qualitatively the effects of electromigration and speciation, and serve as a reasonable first approximation, they do not capture the non-uniform distribution of concentrations, mass transfer rates or saturation indices. The model will be used to study the full length of an RO membrane module and thus provide better indicators of the overall performance of the separation process.

2D numerical modeling of solute transport Na-K from a geothermal reservoir: The case of Las Tres Vírgenes, BCS

Las Tres Vírgenes geothermal field (LTVGF) is located within the volcanic complex of the same name with temperatures between 250 and 275 °C and a total power generation capacity of 10 MW. For geothermal systems, understanding the thermodynamic-chemical equilibrium of the fluid-rock interaction allows us to study the reactions involved in the precipitation or dissolution of minerals. In this work, we use the hydrothermal alteration mineralogical phases albite, microcline, and zoisite that are in equilibrium with the geothermal fluid as a source of cations (Na+, K+, and Ca2+) to model the chemical composition of the geothermal fluids in the last 20 years. The heat transfer (conductive-convective) and solute transport (advective-diffusive) equations in 2D, were discretized using the Finite Volume Method (FVM) and were coupled to simulate the temperature profile and spatial distribution of the main cations in the LTVGF reservoir. The code evaluates the thermal and chemical evolution of the reservoir from an initial geothermal gradient and an initial chemical composition of the fluid to reach the present concentrations at reservoir conditions. Based on the model results, we consider a reservoir between 1000 and 2000 m in depth and initial concentrations of 100 ppm for sodium to get the average concentrations at reservoir conditions of wells LV-13, LV-11, LV-6, LV-3, LV-4, and LV-1 corresponding to values between 3138 and 3661 ppm and temperatures between 225 and 249 °C. For potassium, the initial concentration was 10 ppm to reproduce the average concentrations between 604 and 663 ppm for wells LV-13, LV-11, LV-4, and LV-5 obtaining temperatures between 223 °C and 257 °C. For calcium, the initial concentration was 2 ppm and reproduced the concentrations of wells LV-5 and LV-6 (251 and 260 ppm) which are at depths of 1737 and 2162 m and temperatures of 225 and 260 °C. This work presents perhaps the first approach to solute transport of the LTVGF reservoir and it was determined that the alteration minerals considered influence the chemical composition of the current discharge fluids of the field. These results promote using Na/K geothermometers based on ionic activities proposed in the literature to estimate the reservoir temperature according to the equilibrium conditions and the chemical composition of the fluids.

Presentation and Performance of a Planar Solid Oxide Fuel Cell with Chaotic Gas Channels

Flow condition in gas channels determines the distribution and diffusion of reactants, governing electrochemical reactions in the solid oxide fuel cell (SOFC). It is found that the magnitude and direction of fluid velocity change with the geometric position in the channel, which leads to larger secondary flow velocity components and enhances mass transfer between fluids. Laser Doppler velocimetry experiment is conducted to verify the accuracy of numerical results of fluid flow in chaotic flow channels. Herein, a 3D numerical model with coupled multiphysics fields is built to evaluate fluid flow in channels and SOFC performance. The distribution characteristics of reactants in chaotic flow channel and the characteristics of temperature distribution, current density and power density in SOFCs caused by structures of straight and chaotic flow channels are analyzed and discussed. Compared with conventional straight flow channel SOFCs, the average current density of SOFC with chaotic flow channel is improved and the power density is increased by 9.7%. The reactant homogeneity in the electrode is also improved, which reduces the concentration polarization loss of SOFC.

3D numerical modeling of gas atomization process for powder preparation based on similarity theory

Gas atomization is a widely used method to produce metal powders. However, the powders often have a wide range of particle sizes, which is not ideal for additive manufacturing. To visualize the liquid breakup during gas atomization, we have developed a novel approach that combines similarity theory with Navier-Stokes equations. The simulation utilizes the volume of fluid to discrete phase model, which captures both primary and secondary breakups. By analyzing the morphology of the lumps and particles produced by a closed-coupled atomizer, the results have shown that approximately 30% of the lumps formed turn into fibers, and 68% secondary breakup mode is vibration breakup. Based on these simulations, we propose optimized methods for modifying the liquid outlet and adjusting the gas inlet eccentricity. Overall, our approach provides a new way to directly simulate the entire gas atomization process and offers valuable guidance for gas atomization technology.

Development, verification and experimental validation of a 3D numerical model for tubular solar receivers equipped with Raschig Ring porous inserts

This study presents a numerical investigation of gaseous tubular absorbers used in a solar furnace and introduces a 3D model to simulate porous inserts with random packing of metallic Raschig Rings (RR) at pore-scale. A comprehensive verification and validation process was conducted based on the experimental data obtained at Plataforma Solar de Almeria (SF60). The evaluations were carried out on three samples, including a smooth pipe (SP) and two enhanced pipes (20RR and 40RR) with 20 mm and 40 mm RR inserts. The effects of several influential parameters, such as the fluid turbulence model, the effective thermal conductivity of the porous material, and the randomness of the RR in the porous structure, were studied to assess the accuracy and repeatability of the model in predicting thermal and fluidic characteristics of air inside the absorber pipes under different working conditions. A detailed thermo-hydraulic analysis revealed an irregular flow pattern inside the porous zone, while the air recirculation at the porous entrance and exit provides an uneven pressure drop distribution in the azimuthal direction. Moreover, fluid turbulence is enhanced downstream of the porous insert thanks to several stream jets formed by uneven flow discharge at the insert outlet face, which improves heat transfer in that area. The analyses demonstrated a significant improvement in heat transfer, with a maximum enhancement factor of 10–15 than the smooth tube. Additionally, in the evaluation of thermo-hydraulic performance, the enhanced absorbers exhibit Performance Evaluation Criteria up to 2, compared to the tube without RR inserts.

Thermal Performance of a Flat-Plate Solar Collector for Drying Agricultural Crops

In this study, the finite volume method was used to evaluate the thermal performance of a flat-plate solar collector used to dry agricultural crops. A 3D numerical model was created and used to predict the outlet air velocities and temperatures for three inlet air velocities. When compared with experimental measurements, the numerical predictions showed good agreement under all testing conditions. Then, the numerical model was used to predict the internal airflow and heat transfer characteristics of the collector. The internal baffles were found to increase the dwell time and efficiency but also promote flow separation, which resulted in flow loss. In addition, the collector has a transparent cover that results in a substantial heat loss, which can be mitigated by adding a vacuum gap between the flow inside the collector and the cover. Increasing the flow rate increased the heat loss and decreased the heat uptake, which decreased the temperature difference between the inlet and outlet of the collector. Because the heat was lost through long-wavelength radiation via the transparent cover and sidewalls, coating the absorber plate with black matte paint to increase the solar radiation absorption coefficient did not improve the drying performance.

Quantification of contaminant mass discharge from point sources in aquitard/aquifer systems based on vertical concentration profiles and 3D modeling

Point sources with contaminants, such as chlorinated solvents, per- and polyfluoroalkyl substances (PFAS), or pesticides, are often located in low-permeability aquitards, where they can act as long-term sources and threaten underlying groundwater resources. We demonstrate the use of a 3D numerical model integrating comprehensive hydrogeological and contamination data to determine the contaminant mass discharge (CMD) from an aquitard into the underlying aquifer. A mature point source with a dissolved chlorinated solvent in a clayey till is used as an example. The quantitative determination is facilitated by model calibration to high-resolution vertical concentration profiles obtained by direct-push sampling techniques in the aquifer downgradient of the contaminant source zone. The concentration profiles showed a plume sinking with distance from the source characteristic for such aquitard/aquifer settings. The sinking is caused by the interplay between infiltrating water and horizontal groundwater flow. The application of 3D solute transport modeling on high-resolution profiles allowed for determining the infiltration rate, the hydraulic conductivity in the aquitard, and, ultimately, the CMD. Different source zone conceptualizations demonstrate the potential effects of fractures and sorption in source zones in aquitards on CMD development. Fractures in the aquitard had a minor influence on the current CMD determined with the presented approach. Still, fractures with hydraulic apertures larger than 10 μm were crucial for the temporal development of the CMD and plume. A thorough characterization of the source zone conditions combined with high-resolution concentration profiles and detailed modeling is valuable for shedding light on the probable future development of groundwater contamination arising from sources in aquitard/aquifer settings and evaluating remedial actions.

Development of novel single fuel cell based on composite polar plates for highly efficient power generation

In proton exchange membrane fuel cells (PEMFCs), bipolar plate (BPP) and membrane electrode assembly (MEA) are arranged alternately to construct a fuel cell stack for power generation. This construction method may affect the power generation performance of fuel cell stack or even damage the MEA components. To improve the fuel cell stack's assembly efficiency, we propose a novel single fuel cell that consists of two composite polar plates and a MEA, the composite polar plate is formed by a nylon frame and a titanium thin sheet with microchannels. The structural design of the single cell and its working principles are firstly presented, and followed by the fabrication of the single fuel cell. A three dimensional (3D) numerical model is developed to investigate the internal electrochemical reaction behaviors of the single fuel cell. Then, experimental tests are conducted to test its electrochemical performance for power generation. The obtained results showed that the open circuit voltage can reach 0.93 V and energy density is approximately 813.83 mW/cm3, indicating our developed single fuel cell had a high energy utilization efficiency for power generation. Therefore, our developed single fuel cell has the potential to power unmanned aerial vehicles (UAVs), robotics, and new energy vehicles.

Predictive model of back-wall overpressure behind a cantilever wall

To reduce the hazards posed by blast shock waves, important potential targets are usually shielded by cantilever walls. The main factor that indicates whether there is damage is the back-wall overpressure, and of concern here is predicting the back-wall overpressure behind a rigid cantilever wall. This was measured in full-scale blast experiments using 20 kg of trinitrotoluene (TNT) located on the ground, and the experimental data reveal how the cantilever wall mitigates the shock wave. A 3D numerical model was established to determine how the wall size influences the diffraction of the shock wave and the peaks and attenuation of the back-wall overpressure. Based on the numerical results and dimensional analysis, a model is proposed that provides an effective means of predicting the back-wall overpressure rapidly from the TNT equivalent, the standoff distance, and the height of the wall.

Two-Dimensional Magnetotelluric Forward Modeling in Space-wavenumber Mixed Domain

In magnetotelluric exploration, if you want to do 2D or 3D numerical modelling, what you need in the computational and memory requirements are potentially enormous. In order to get efficient and precise forward simulation results, we propose a new 2D numerical modelling method in space-wavenumber mixed domain. This method uses the one-dimensional Fourier transform in the horizontal directions, so the two-dimensional partial differential equations in the spatial domain can be transformed into a set of independent one-dimensional differential equations with different wave numbers. Then we can use the finite different method to solve the one-dimensional equations. In this article, the COMMEMI-2D1 model was used to verify the accuracy of the algorithm. We compare our results with the traditional finite different method in TE mode, indicating that the algorithm improves computational efficiency.

Probabilistic service life prediction of cracked concrete using numerical and engineering models

AbstractChloride ingress induced depassivation of reinforcing steel leading to corrosion is a major durability concern for concrete structures. The influence of the presence of cracks commonly occurring in concrete structures on chloride ingress should be accounted to improve the accuracy of service life predictions. This study investigates the depassivation probability of the reinforcement in both cracked and uncracked concrete using both analytical and 1D numerical models. The probabilistic service life prediction is realized using the Monte Carlo simulation to incorporate the uncertainty and variability in the input variables. For uncracked concrete the result of the numerical model agreed well with the fib chloride model. For cracked concrete, the numerical simulation suggests that the optimal engineering approach to account for cracks in a service life analysis is the adaptation of crack depth. Although, the approach could lead to an overestimation of chloride concentration because the 1D numerical simulation did not consider lateral diffusion in cracked concrete.

NUMERICAL MODELLING TOXIC SUBSTANCE TRANSPORT IN MINE WATER FLOWS

The purpose of this work is to develop and test a methodology for modelling the migration of toxic substances left after mining in mine water flows in a system of hydraulically connected mine workings of various sizes and elevations depending on the drainage parameters. Methods of research include the analysis of factors that influence the formation of the hydraulic regime in flooded mines, the accumulation and transport of toxic substances. Parameters of moving toxic substances in mine waters are calculated using hydraulic flow equations written for mining workings, with flooded workings being considered as pipelines with distributed recharge. Modelling of non-stationary 1D transport in water from local sources of toxic substances was performed using the finite difference method. Results. Flow rates and velocities in flooded mine workings on two hydraulically connected horizons of different elevations were calculated. For different locations of sources of toxic substances on the example of polychlorinated biphenyls, their concentrations in mine waters along the migration path and at the water hoisting at different flow rates were calculated. The influence of increased water withdrawal, dilution with additional recharge along the migration path and the position of potential sources of substances in the flooded mine were investigated. It wasshown that for the considered example, increasing the water outflow rate by two times accelerates the stabilisation of mass transport with an increase in the daily removal of substances by 3.4–6.4 times, which is more active from the upper horizon. Scientific novelty. For the first time, the transport of substances in flooded workings was simulated by combining a hydraulic flow model with a numerical transport model. Unlike 2D and 3D numerical transport models based on solid mechanics, which average the concentration in the grid blocks, the proposed approach allows the reproduction of the geometry of the mined-out space more accurately. It provides a more realistic distribution of flow velocities and concentrations depending on the parameters of the mine water withdrawal, depth of mine workings, and the mine water level. Practical significance. Using the tested methodology will make it possible to perform engineering predictions of the quality of groundwater and surface water near closed mines for different periods at different levels of flooding, water withdrawal rates and depths of the pumps for mine water drainage. In addition, the proposed technique can be used to justify the conceptual scheme of the numerical hydrogeochemical model of the post-mining areas. Keywords. Close mines, toxic substances, flooded workings, hydraulic flow, water hoisting, transport model.