Diffusion Front Research Articles

Longitudinal splitting and grouting in deep buried rock layers based on the coupling effect between slurry and rock

The coupling effect between slurry and a fractured rock layer controls the width of the fracturing channel and the grouting pressure. This effect is attenuated as the slurry diffusion front spreads from the grouting hole. This study examined the motion of slurry and the fracture expansion process, thereby establishing a longitudinal grout-splitting model of slurry-rock coupling by deriving a slurry-splitting diffusion motion equation that considers the time-varying viscosity of the slurry and attenuation of the fracture width. Research has demonstrated that in the initial stage of grouting, the plastic viscosity of the slurry is low, making grouting pressure and grouting rate the main determinants of the slurry’s splitting and diffusion range, as both factors can significantly expand the diffusion range of the slurry. However, once the viscosity of the slurry exceeds a certain threshold, viscosity becomes the primary factor that restricts the diffusion range of the slurry. Therefore, when using a slurry with time-varying viscosity, a higher initial grouting rate and grouting pressure should be selected in the early stages of grouting. As the grouting pressure stabilizes, the viscosity of the slurry should be appropriately increased to enable the slurry to quickly gel and seal the fractures.

Modeling of drug release, erosion and diffusion fronts movement in high viscosity HPMC matrices containing a cellulolytic enzyme

A formerly developed mathematical model describing drug release from hydrophilic matrices (HMs) took into account resistance to drug release given by its dissolution and by the presence of a growing gel layer. Such a model was applied to previously reported release data obtained from HMs made of hydroxypropyl methylcellulose (HPMC), where acetaminophen was used as model drug and a cellulolytic product was added as “active” excipient to attain zero-order release kinetics. The Levich theory applied to acetaminophen intrinsic dissolution rate (IDR) data highlighted the suitability of such a drug for modeling purposes, given its good surface wettability. First assessment of the model ability to describe drug release from the abovementioned systems was carried out on partially coated matrices, representing a simplified physical frame, but results were then confirmed on uncoated systems. Experimental and model release data showed good agreement; therefore, the release-describing equation was combined with that of the global mass balance to obtain two new equations related to erosion and diffusion fronts time evolution. Changes over time in the dissolution and gel contributions to total resistance, calculated using model output parameters, highlighted that the enzyme, through its hydrolytic activity on HPMC, was responsible for a time-dependent reduction of the resistance component related to gel layer.

Injection-induced seismic moment in layered rock formations

Appropriate estimation of seismic moment release during fluid injection is critical to mitigate the risk of induced seismic hazards and to guide safe operation in the geo-energy industry. However, the present single-layer models overlook the contributions of fault slip in different rock layers to the seismic moment release. Here we report an analytical model incorporating a multiple-layer function to predict the injection-induced seismic moment in layered rock formations. This model is established based on fault slip triggered by aseismic motion, particularly considering the locations of aseismic slip front and fluid diffusion front on a seismogenic fault in relative to the layer interface. We compare the maximum seismic moment obtained from our model to those estimated from three single-layer models and those measured from eleven field cases. The results highlight possible underestimation of the maximum seismic moment using the single-layer models in the layered rock formations. We also emphasize that a proper selection of layer model is significant to reasonably assess the seismic moment release. Lastly, we apply both the single-layer and double-layer models to predict the maximum seismic moment of the 5 February 2019 Mw 4.0 earthquake in the Weiyuan Shale Gas Field in Sichuan, China. The engineering application further confirms the necessity of using the double-layer model in the layered rock formations. Additionally, the assessment of amplification factors for fault segments provides a better understanding of induced seismic hazards in different rock layers and possibly guides the safety threshold of injection rate during fluid injection.

Interplay Between Unburned Emissions and NOx Emissions From a Dual Swirl Hydrogen Air Injector

Abstract OH planar laser induced fluorescence (OH-PLIF) and particle image velocimetry (PIV) are employed to analyze the structure of hydrogen/air flames stabilized by a dual swirl injection system under globally lean and atmospheric conditions with preheat air temperature varied from ambient up to 673 K. The flames exhibit two distinct reaction branches. The first, located in the central recirculation zone (CRZ), is a diffusion-controlled reaction layer characterized by a relatively large thickness associated with low strain rates. The second branch, stabilized in the shear layer of the swirling jet, is strongly influenced by large coherent structures. Depending on operating conditions, this front may adopt either the form of a fully diffusive strained reaction layer anchored to the hydrogen injector lip or a lifted diffusion front with a leading-edge flame evolving into a partially premixed flame at high air injection velocities. Flue gas analysis indicates NOx emission levels, typically below 10 ppm at 15% O2, for sufficiently large air injection velocities. Air preheating barely increases NOx emissions at lean operating conditions. The injector operational range is constrained only by the ultralean blowout limit reached for global equivalence ratios below 0.02. Furthermore, it demonstrates remarkable resilience to large and rapid drop in fuel flow rate. However, combustion efficiency drops close to the lean blowout (LBO) limit due to intermittent fragmentation of the flame wings that progresses further upstream as the equivalence ratio drops. The results demonstrate that fragmentation arises from the combined effects of a temperature drop in the central recirculation zone and the flame wings being exposed to high shear stress. Additionally, it is shown that combustion efficiency under ultralean conditions improves significantly with an increase in air preheat temperature.

The Kinetics of Polymer Brush Growth in the Frame of the Reaction Diffusion Front Formalism.

We studied the properties of a reaction front that forms in irreversible reaction-diffusion systems with concentration-dependent diffusivities during the synthesis of polymer brushes. A coarse-grained model of the polymerization process during the formation of polymer brushes was designed and investigated for this purpose. In this model, a certain amount of initiator was placed on an impenetrable surface, and the "grafted from" procedure of polymerization was carried out. The system consisted of monomer molecules and growing chains. The obtained brush consisted of linear chains embedded in nodes of a face-centered cubic lattice with excluded volume interactions only. The simulations were carried out for high rafting densities of 0.1, 0.3, and 0.6 and for reaction probabilities of 0.02, 0.002, and 0.0002. Simulations were performed by means of the Monte Carlo method while employing the Dynamic Lattice Liquid model. Some universal behavior was found, i.e., irrespective of reaction rate and grafting density, the width of the reaction front as well as the height of the front show for long times the same scaling with respect to time. During the formation of the polymer layer despite the observed difference in dispersion of chain lengths for different grafting densities and reaction rates at a given layer height, the quality of the polymer layer does not seem to depend on these parameters.

Spontaneous imbibition in thin anisotropic fibrous media: Experiments and numerical modeling

In this study, we investigate the temporal and spatial evolution of wetting saturation during spontaneous imbibition in anisotropic fibrous porous media using both experimental and numerical methods. We present a novel experimental approach to systematically study spontaneous imbibition in these media, allowing for a comprehensive assessment of how microstructure influences wicking performance. The experimental method, which exhibits high reproducibility, was used to validate the numerical model. The numerical model was parameterized using only the porosity and filament diameter of the porous media in conjunction with the material properties of the imbibing fluid. The essential capillary saturation curve for the numerical model was derived using the pore morphology method. The numerical results effectively replicated the experimental results. Our experimental and numerical observations revealed a diffusive wetting front within the porous media, which progressively expanded and decelerated during the imbibition process. The results highlight the significant influence of filament size on the wetting saturation dynamics and the height of the wetting front during spontaneous imbibition.

Nanoparticle uptake by a semi-permeable, spherical cell from an external planar diffusive field. II. Numerical study of temporal and spatial development validated using FEM

In this paper, we present a mathematical study of particle diffusion inside and outside a spherical biological cell that has been exposed on one side to a propagating planar diffusive front. The media inside and outside the spherical cell are differentiated by their respective diffusion constants. A closed form, large-time, asymptotic solution is derived by the combined means of Laplace transform, separation of variables, and asymptotic series development. The solution process is assisted by means of an effective far-field boundary condition, which is instrumental in resolving the conflict of planar and spherical geometries. The focus of the paper is on a numerical comparison to determine the accuracy of the asymptotic solution relative to a fully numerical solution obtained using the finite element method. The asymptotic solution is shown to be highly effective in capturing the dynamic behaviour of the system, both internal and external to the cell, under a range of diffusive conditions.

Water diffusion in coal: The competing effects of wettability, fracture size, and gravity

Waterflooding of coal seam is an effective method for dust control and gas outburst control. This work utilized a visual coal waterflooding device to investigate the macroscopic water diffusion in coal matrix and the influence of coal wettability, coal fracture size, and gravity on water diffusion and wetting. The results showed that water diffusion front in coal was flat and steadily advancing when coal was hydrophobic. The diffusion front of small fracture coal was more stable than that of large fracture coal. Water diffused faster in hydrophilic coal than in hydrophobic coal. Water diffused faster in large fracture coal than in small fracture coal. The influence of fracture size on water diffusion was more obvious in hydrophobic coal than in hydrophilic coal. Gravity scarcely affected water diffusion in hydrophilic and hydrophobic coal. The research results have significant reference value for guiding coal seam waterflooding for dust control.

Wearable Alcohol Monitoring Device for the Data-Driven Transcutaneous Alcohol Diffusion Model.

Wearable alcohol monitoring devices demand noninvasive, real-time measurement of blood alcohol content (BAC) reliably and continuously. A few commercial devices are available to determine BAC noninvasively by detecting transcutaneous diffused alcohol. However, they suffer from a lack of accuracy and reliability in the determination of BAC in real time due to the complex scenario of the human skin for transcutaneous alcohol diffusion and numerous factors (e.g., skin thickness, kinetics of alcohol, body weight, age, sex, metabolism rate, etc.). In this work, a transcutaneous alcohol diffusion model has been developed from real-time captured data from human wrists to better understand the kinetics of diffused alcohol from blood to different skin epidermis layers. Such a model will be a footprint to determine a base computational model in larger studies. Eight anonymous volunteers participated in this pilot study. A laboratory-built wearable blood alcohol content (BAC) monitoring device collected all the data to develop this diffusion model. The proton exchange membrane fuel cell (PEMFC) sensor was fabricated and integrated with an nRF51822 microcontroller, LMP91000 miniaturized potentiostat, 2.4 GHz transceiver supporting Bluetooth low energy (BLE), and all the necessary electronic components to build this wearable BAC monitoring device. The %BAC data in real time were collected using this device from these volunteers' wrists and stored in the end device (e.g., smartphone). From the captured data, we demonstrate how the volatile alcohol concentration on the skin varies over time by comparing the alcohol concentration in the initial stage (= 10 min) and later time (= 100 min). We also compare the experimental results with the outputs of three different input profiles: piecewise linear, exponential linear, and Hoerl, to optimize the developed diffusion model. Our results demonstrate that the exponential linear function best fits the experimental data compared to the piecewise linear and Hoerl functions. Moreover, we have studied the impact of skin epidermis thickness within ±20% and demonstrate that a 20% decrease in this thickness results in faster dynamics compared to thicker skin. The model clearly shows how the diffusion front changes within a skin epidermis layer with time. We further verified that 60 min was roughly the time to reach the maximum concentration, Cmax, in the stratum corneum from the transient analysis. Lastly, we found that a more significant time difference between BACmax and Cmax was due to greater alcohol consumption for a fixed absorption time.

Evaporation of binary liquids from a capillary tube

Evaporation of multi-component liquid mixtures in confined geometries, such as capillaries, is crucial in applications such as microfluidics, two-phase cooling devices and inkjet printing. Predicting the behaviour of such systems becomes challenging because evaporation triggers complex spatio-temporal changes in the composition of the mixture. These changes in composition, in turn, affect evaporation. In the present work, we study the evaporation of aqueous glycerol solutions contained as a liquid column in a capillary tube. Experiments and direct numerical simulations show three evaporation regimes characterised by different temporal evolutions of the normalised mass transfer rate (or Sherwood number $Sh$ ), namely $Sh (\tilde{t} ) = 1$ , $Sh \sim 1/\sqrt {\tilde{t} }$ and $Sh \sim \exp (-\tilde{t} )$ , where $\tilde {t}$ is a normalised time. We present a simplistic analytical model that shows that the evaporation dynamics can be expressed by the classical relation $Sh = \exp ( \tilde{t} )\,\mathrm {erfc} ( \sqrt {\tilde{t} })$ . For small and medium $\tilde{t}$ , this expression results in the first and second of the three observed scaling regimes, respectively. This analytical model is formulated in the limit of pure diffusion and when the penetration depth $\delta (t)$ of the diffusion front is much smaller than the length $L(t)$ of the liquid column. When $\delta \approx L$ , finite-length effects lead to $Sh \sim \exp (-\tilde{t} )$ , i.e. the third regime. Finally, we extend our analytical model to incorporate the effect of advection and determine the conditions under which this effect is important. Our results provide fundamental insights into the physics of selective evaporation from a multi-component liquid column.

Numerical Simulation of the Self‐Organizational Origin of Concentrically Zoned Aggregates of Siderite and Pyrite in Sediment‐Hosted Massive Sulfide Deposits

AbstractConcentrically zoned pyrite aggregates (CZPA) are common in sediment‐hosted massive sulfide (SHMS) deposits and have been widely used to interpret the ore‐forming processes. There is considerable uncertainty, however, over the formation of aggregates that are oscillatorily zoned and contain randomly‐orientated pyrite microcrystals. Guided by the results of examination of the micro‐textures of CZPA and in‐situ chemical analyses, we conducted a quantitative diffusion‐reaction simulation to assess the mechanism of CZPA formation. Our study shows that oscillatory zoning results from the feedback between the diffusion of reactants and the nucleation‐growth of Fe‐sulfides. Externally derived Fe2+ diffuses into the early diagenetic sediments containing decomposing organic matter (2CH2O + SO42− = 2HCO3− + H2S) and reacts with H2S to form a pyrite layer via an intermediate pathway (Fe2+ + H2S → FeS + 2H+, FeS + H2S → FeS2 + H2). This growth of pyrite layers depletes the local concentration of reactants and suppresses nucleation until the diffusive reaction front advances and another layer is formed. Intermediate phases, for example, mackinawite, nucleate instead of pyrite, because of their greater ease of nucleation due to the low surface tension, and lead to the domination of nucleation over growth. The nucleation of mackinawite and occurrence of siderite in the CZPA are consistent with a low temperature, high pH, anoxic early diagenetic environment. Our study demonstrates that CZPA in SHMS deposits are formed by intrinsic self‐organizational processes rather than by extrinsic changes of ore‐forming fluids. The CZPA in SHMS deposits are thus indicative of their diagenetic origin with Fe2+ infiltrated and diffused from hydrothermal fluids into the sediments.

Strontium concentration spikes as evidence for fluid-driven carbonate dissolution during subduction

Carbonate dissolution, the process by which carbonate minerals are stoichiometrically dissolved by an aqueous fluid, likely plays an important role in liberating carbon from subducting slabs and may thus make significant contributions to global carbon fluxes. It is therefore necessary to understand the fluid infiltration and flow geometries associated with this process. Despite its widespread use as a powerful tracer of fluid-rock interaction, strontium (Sr) has yet to be widely applied to carbonate dissolution scenarios. Previous work has identified a partially altered metacarbonate layer from Syros, Greece, that has undergone significant carbonate dissolution leading to ∼90% CO2 loss (Ague and Nicolescu, 2014). A bulk-rock compositional profile along this layer has a distinctive spike-shaped Sr profile. Sr concentrations are uniform in the altered region behind the reaction front, increase to form a spike just ahead of the front, and taper off to a baseline value moving farther into the unaltered metacarbonate rock. The origin of this type of spike shape and its potential utility for better understanding carbonate dissolution processes remain unaddressed. Here, we present a numerical diffusion-reaction model which demonstrates that both carbonate dissolution and multidimensional transport of Sr, in which the primary advective flow direction is perpendicular to the propagation of the diffusion front, are required to produce this shape. This model, as well as newly acquired Sr concentration data for calcite (former aragonite) and epidote, also indicate that the infiltration of a fluid with an elevated Sr concentration is necessary. We suggest that such spike-shaped features may aid in identifying carbonate dissolution in other settings, such as vein-selvage systems in metacarbonate rocks or reaction rinds on carbonate-bearing mélange blocks.

Lightly doped In0.53Ga0.47As/InP SWIR photodetectors with diffusion barrier structure

A diffusion barrier structure is proposed to control the accuracies of the Zinc diffusion velocity and depth for lightly doped short-wave infrared (SWIR) InGaAs planar photodetectors. By employing scanning capacitance microscopy and scanning electron microscopy characterizations, the Zinc diffusion profiles were investigated. The introducing of a moderately doped interlayer effectively tailored the diffusion front with reduced depth. In0.53Ga0.47As/InP PIN photodetectors with different structures were fabricated and characterized. Compared with the typical structure, the barrier detector exhibited a significantly lower dark current as well as an approximately three times higher peak detectivity. These results indicated that the diffusion barrier structure is promising for the fabrication of SWIR InGaAs focal plane arrays with both low capacitance and reduced dark current.

Investigation of the Diffusion of Chloride Ions in Blended Cement Pastes

AbstractWhen exposed to aggressive environments containing chlorides, the chlorine ion partially binds to the usual Portland cement mortar and changes its mineralogy. Chlorine ions entering the system displace sulfate from the monosulfoaluminate. Such systems form Kusel's salt at low chloride concentrations and Friedel's salt at higher concentrations. Unbound chloride ions remain dangerous for reinforcing steel, which diffuse deep into the concrete and destroy the passivating layer on the reinforcement. To assess the protective properties of concrete in relation to metal reinforcement, it is proposed to investigate the process of displacement of the diffusion front in cement composites of various compositions. It is also important to study changes in such characteristics as porosity and filtration properties, which significantly affect the penetration depth of an aggressive medium. The study of the structure, mineral and chemical composition is carried out in layers.

Formation of Precipitation Ellipsoidal Disks and Spheres in the Wake of a Planar Diffusion Front.

Pattern formation is one of the examples of self-organization. In the generation of patterns, the coupling between the mass transport of the chemical species and their chemical reactions plays an important role. Periodic precipitation (Liesegang phenomenon) is a type of pattern formation in which layered precipitation structures form in the wake of the diffusion front. Here, we show a new type of precipitation pattern formation in zeolitic imidazolate framework-67 in a solid hydrogel column in a test tube manifested in the generation of precipitation ellipsoidal disks and spheres in the wake of the planar diffusion front of the outer electrolyte (2-methylimidazole). To increase the probability of the emergence of ellipsoidal disks and spheres, the surfaces of the borosilicate test tubes were chemically treated and functionalized. To support the experimental findings, we developed a reaction-diffusion model that qualitatively describes the formation of precipitate ellipsoidal disks and spheres in a test tube.

Predicting residual stresses in SLM additive manufacturing using a phase-field thermomechanical modeling framework

Additive manufacturing (AM) of metallic components has recently become a viable option for series production. In this, the powder of various metallic materials such as steel and aluminum can be processed layer-by-layer to produce dense parts with excellent properties. One of the major challenges in this process is the occurrence of residual stresses, which negatively affect the strength and functionality of the produced components. Understanding the mechanism of distribution of these stresses and the detrimental deformations is one of the main themes covered in this work. In the numerical treatment with the finite element method, a phase-field model (PFM) for phase-change materials is utilized together with a thermo-elastoplastic model to simulate the multi-layer AM process and to evaluate the occurring residual stresses. Using the PFM allows tracking the diffusive melting front and, thus, distinguishing between the melted (soft) and the unmelted (hard) states of the material. One of the novel contributions is the definition of a phase-field history variable, which can capture the irreversible process of metallic powder melting. Additionally, phase-field-dependent material properties are proposed. The coupled governing equations are solved in the open-source FE package FEniCS Project, where three-dimensional initial-boundary-value problems are introduced and the results are compared with reference data from the literature.

Quantifying the mechanisms of rain-triggered seismicity in karstic regions

Seismicity following heavy rainfall events is often considered to be triggered by the pore pressure diffusion front migrating from the surface towards the focal depth, assuming a homogeneous crust. Although this assumption can be justified in some cases depending on local geology (e.g., a homogeneously fractured basement), it is too simplistic for known karst areas. Indeed, the hydraulic behaviour of karst during a flood event is not dominated by pressure diffusion but by highly transmissive karst conduits. This generates rapid and large variations in hydraulic head, possibly leading to large changes in pore pressure at seismogenic depth. We consider the conditions and data from three different case studies with karstic features to evaluate possible seismicity-triggering mechanisms. We identify four potential mechanisms to explain the influence of rainfall on fault stability: crustal loading and its associated poroelastic deformation, pore pressure diffusion, and direct hydraulic connection. We quantify the effect of these mechanisms for parametrisation corresponding to our case studies by considering the specific features of karst and using simplified analytical solutions. Results show that the pore pressure increase resulting from the crustal loading and poroelastic deformation is much smaller than the pore pressure increase resulting from a direct hydraulic connection and its diffusion towards depth over small distances. Moreover, the timing between the intense precipitations and the beginning of seismicity may indicate the mechanism behind the triggering process: no time lag to a time lag of a few hours supposes a direct hydraulic connection, whereas a time lag of a few hours to a few days suggests a coupled solution of a rapid pressure increase resulting from direct hydraulic connection followed by the diffusion process prograding towards the focal depth. Our results highlight the importance of considering the intrinsic properties of karst and its spatial distribution, especially its depth, when studying rain-triggered seismicity in a karstic environment.

Evidences for diffusion-induced phase evolution and crack generation of intermetallic at Bi2Te3/Sn interface of thermoelectric generator electrode

Bismuth telluride-based thermoelectric generators (TEG) were widely used in waste heat recovery, but the failure problem at the electrode interface was serious, which was related to the severe diffusion between Sn and Bi2Te3. However, the diffusion behavior and process have not been reasonably evaluated and mechanism analyzed, which was not conducive to the design and improvement of TEGs. In this work, hot-end electrode aging was performed at 150 °C, and the diffusion, intermetallic compounds (IMC), as well as crack induction between Bi2Te3 and Sn-based solder were systematically investigated. It was found that the interdiffusion of Sn and Te atoms led to the formation of Bi2Te with HCP structure and SnTe with FCC structure at the interface. Bi2Te was a Bi-rich layer formed after the migration of Te atoms away from Bi2Te3, and SnTe had a double-layer structure respectively attributing to the diffusion of Sn and Te atoms. Diffusion-induced cracks tended to occur at Bi2Te/SnTe interfaces and SnTe/Sn interfaces. The former was related to the diffusion-induced phase transformation at the diffusion front of Sn atoms, while the latter generated from the initiation and expansion of Kirkendall voids. In addition, the brittleness of the Bi-rich phase aggravated the crack propagation. The shear test results of the electrodes confirmed that these cracks were the weakness of TEG electrodes. It was recommended to introduce a barrier layer at the interface to provide protection, and the fabrication of direct soldering was not suggested.

Silicon diffusion in AlN

In this study, we investigate the diffusion of Si donors in AlN. Amorphous Si1−xNx sputtered on the surface of bulk AlN with low dislocation density is used as a Si source. The diffusion experiments are conducted through isochronal and isothermal annealing in a protective N2 atmosphere at temperatures between 1500 and 1700 °C. The Si depth profiles measured by secondary ion mass spectrometry exhibit a convex box-like shape with a steep diffusion front. These concentration profiles are best described with a diffusion coefficient that depends on the square of local Si concentration. From the characteristic box-shaped Si profiles, we conclude that diffusion of Si in AlN is mediated by singly negatively charged dopant–vacancy pairs SiAlVAl−. The strong concentration dependence of Si diffusion is due to the electric field associated with the incorporation of Si donors (SiAl+1) on substitutional Al lattice sites and reflects that Si is fully electrically active at diffusion temperature. The experimentally obtained extrinsic Si diffusion coefficient is reduced to intrinsic doping conditions. The temperature dependence of Si diffusion for intrinsic conditions is described by an activation enthalpy of (10.34±0.32)eV and a pre-exponential factor of 235−203+1485cm2s−1. The migration enthalpy of the donor–vacancy pair SiAlVAl− is estimated to be around 3.5 eV. This estimation is based on the activation enthalpy of the transport capacity of SiAlVAl− and theoretical results concerning the formation energy of negatively charged vacancies on Al-sites in AlN.

Study on hydrodynamic diffusion law of the swelling particle slurry in karst pipeline

The swelling particle grouting material has demonstrated remarkable plugging effectiveness in high-pressure and large-flow burst water within karst pipelines. Currently, current research on the rheological model, flow computation theory, and plugging mechanism of this material is lacking. The conventional grouting slurry diffusion process, using the liquid-liquid two-phase flow method, fails to accurately simulate high solubility slurry and particle swelling. To address these limitations, this study established a precise constitutive model to describe the swelling particle slurry diffusion process in dynamic water. Additionally, a coupling calculation method was proposed to analyze the spatiotemporal heterogeneity of viscosity during slurry diffusion by considering the migration of slurry and the changes in viscosity. To investigate the interaction between particle swelling and flow field changes, a Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupling model was developed for the diffusion of swelling particle slurry. It is demonstrated that slurry viscosity increases exponentially within the diffusion front as the particle swelling rate rises, and the drag force exhibits an intriguing behavior of initially increasing and then decreasing as the slurry flows through the pipeline. Furthermore, the CFD-DEM coupling model proved to be more accurate in describing viscosity distribution and diffusion distance compared to the finite element solution. The primary objective of this paper is to reveal the plugging mechanism and provide theoretical support for the engineering application of the swelling particle grouting material.