Two-dimensional Numerical Model Research Articles

Fluid resonance in the narrow gap for a box close to a bottom-mounted wall with permeable bed

The behavior of fluid resonance in a narrow gap formed between a ship and a wharf on a permeable bed is investigated by using a two-dimensional viscous numerical model based on OpenFOAM package. The influence of the permeable bed is significant in the region of low-frequency and resonant frequency ranges, where the decreased free surface amplitude in the narrow gap can be observed, especially for large box draft and large porosity. The increased effect of permeable bed can be generated by large bed thickness and small bed width. With the increase of incident wave amplitude, the influence of permeable bed gives rise to weak. All of these phenomena can be explained by the variation of the fluid entering the seepage surface, where the large vertical velocity and more fluid volume entering the permeable bed can be computed for the cases of larger permeable bed effect. Finally, the variation tendency of wave forces on the box and the wall is consistent with that of wave amplitude in the narrow gap.

Study on Thermal Disturbance of Frozen Soil Around Piles by Concrete Hydration Heat

In order to study the influence of the heat of hydration of concrete on the thermal disturbance of the frozen soil around the pile during the construction of cast-in-place piles in permafrost regions, a two-dimensional temperature field numerical model was established with non-steady state based on the heat conduction control equation and the freezing-thawing phase transition process. This model has been used to analyze and discuss the refreezing process of the concrete pile foundation, the heat flow transfer process between the pile foundation and the frozen soil, and the positive temperature curing process of the pile body. The research results have shown that the refreezing process of the pile foundation is a slow process. It took 28 days after the completion of the pile foundation construction that the negative temperature arose at the bottom of the pile. And 196 days after construction the temperature at the center of the pile dropped to negative. The heat brought by the cast-in-place pile is mainly released to the surrounding soil through the horizontal heat flow, and the thermal conductivity of the soil has a greater influence on this process.

Discrete element simulation on failure mechanical behavior of transversely isotropic shale under two kinds of unloading paths

Based on the discrete element method, a two-dimensional numerical model of shale with different bedding inclinations was established. Using this model, the macro-and meso-mechanical properties of bedded shale under different unloading paths and bedding inclination were studied. In this study, the damage mechanism of bedded shale during the unloading process is revealed. The simulation uses the displacement-controlled loading method, with a loading speed of 0.05 m∙s−1. The results indicate that the bedding inclination of the shale has a significant impact on both mechanical parameters and failure modes under unloading. The peak strength and the ultimate bearing capacity show a “U” shape trend under both unloading paths. Observations of maximum values are observed at β = 0° or β = 90° while observing the minimum values at β = 30°or β = 45°. The failure mode of shale specimens with β = 0° at lower initial confining pressure, the failure mode is splitting damage along the multiple bedding plans, which gradually changes to shear damage with increasing initial confining pressures crossing the weak surface. The failure mode of the specimens with β = 15–45° at different initial confining pressure is shear-slip damage along the bedding planes. And shale at β = 60–90° failure modes are all conjugate shear damage intersecting with the weak surface. The damage to the specimen caused by unloading and increasing the axial stress is greater than that caused by the unloading and constant axial strain. The effects of β = 0° and 90° on microcracking and stress distribution within the specimen are significantly smaller than for the other bedding inclinations.

Principal Parameters Analysis of the Double-Elastic-Constrained Flapping Hydrofoil for Tidal Current Energy Extraction

Taking the rigid NACA0012 airfoil as the object, the key structural parameters of the spring–mass system that govern the dynamics of the double-elastic-constrained flapping hydrofoil are numerically studied in this paper. A two-dimensional numerical model, based on the CFD software FINE/Marine, is established to investigate the influence of the spring stiffness coefficient, frequency ratio, and damping coefficient on the motion and performance of the flapping hydrofoil. This study demonstrates that when the structural parameters are adequately adjusted, the power factor exceeding 1.0 has been achieved, and the corresponding efficiency is up to 37.8%. Moreover, this system can start and work within a wide range of damping coefficients. However, the hydraulic efficiency and power coefficient are sensitive to the change in damping coefficient, so it is very necessary to design an appropriate power output. Lastly, the most obvious parameter affecting the energy acquisition performance is the spring stiffness coefficients. Frequency ratios in the two directions have little influence on the peak value of the power coefficient, but they will cause the change of damping coefficients of the peak point. The key structural parameters studied in this paper provide a useful guideline for an optimized design of this interesting system through searching for the best performance.

Mathematical modeling and performance evaluation of a cathodic bi-population microfluidic microbial fuel cell

Microfluidic microbial fuel cell, as a novel achievement of miniature microbial fuel cell, can be used in various fields such as poison detection, biosensors, etc. To investigate the mass transport and bacterial distribution inside the microfluidic microbial fuel cell, an innovative two-dimensional numerical model of microfluidic microbial fuel cell is proposed in this paper. This model is built via finite element method and the growth of bi-population microorganisms (exoelectrogens and facultative anaerobic bacteria) are coupled into the bioelectrochemical reaction kinetics. The accuracy of the present model is ensured by comparing the simulation results with other studies. After that, the effects of pH, dissolved oxygen and electrode porosity on the cell performance and spatial distribution of microorganisms are explored. Conclusions indicate that the pH gradient caused by the accumulation of hydrogen ions and hydroxide ions inhibits the growth of bacteria and mainly affects the anode performance. Higher electrode porosity enhances substrate transport and facilitates microbial growth. However, the effective conductivity of porous electrodes decreases with increasing porosity, which increases ohmic loss. Therefore, MMFC achieves an optimal power density of 956 W m−3 at a porosity of 0.6. Higher dissolved oxygen concentration contributes to enhancing the performance of microfluidic microbial fuel cell. The proposed model can provide strategies for the optimal design of microfluidic microbial fuel cell.

Field observation and numerical modelling of supersaturated dissolved gas at river confluence

Confluences are common habitats of ecological significance given their complicated hydraulic structures and mass transportation. In hydropower cascades, dissolved gas supersaturation downstream of a dam becomes a negative environmental impact caused by dam spilling, which may cause fish to suffer from gas bubble disease and even death. A difference in the supersaturation level of dissolved gas is consistently noted between the mainstream and tributaries mainly due to their different cascade developments and dam scales, resulting in a significant nonuniform distribution of dissolved gas at a confluence. This study focused on describing the hydrodynamics and dissolved gas distributions under unsteady inflows at an actual confluence of the Min River and Jinsha River in China. A long period of prototype observations on dissolved oxygen (DO) were conducted to demonstrate DO variation at the confluence and calibrate the DO dissipation coefficient. A depth-averaged two-dimensional numerical model was developed that reflects the nonconstant characteristics of flow and supersaturated DO at the confluence and was verified to be in good agreement with the measured data series. The supersaturated DO level at the confluence increases as the inflow DO level of the mainstream Jinsha River increases and decreases as the flow ratio of the branch Min River and Jinsha River increases, representing two aspects influencing the distribution of DO at the confluence. A comparison was performed to evaluate the DO saturation calculation method when DO was laterally mixed downstream of the confluence. The accuracy of the flow weighted average calculation based on the data of the mainstream and a tributary upstream of the confluence was acceptable, but the simulation method was recommended to obtain a refined distribution and spatial utilization of supersaturated DO at the confluence when it was necessary to pay more attention to the ecological function in this region. A two-dimensional unsteady numerical model based on valuable prototype observations was proposed, which provides technical tools for characterizing the hydrodynamics and dissolved gas variations and distributions at confluences and better evaluating the risk for fish in regions of great ecological significance.

Grain-size-evolution controls on lithospheric weakening during continental rifting

Variation in the effective strength of the lithosphere allows for active plate tectonics and is permitted by different deformation mechanisms operating in the crust and upper mantle. The dominant mechanisms are debated, but geodynamic models often employ grain-size-independent mechanisms or evaluate a single grain size. However, observations from nature and rock deformation experiments suggest a transition to grain-size-dependent mechanisms due to a reduction in grain size can cause lithospheric weakening. Here, we employ a two-dimensional thermo-mechanical numerical model of the upper mantle to investigate the nature of deformation and grain-size evolution in a continental rift setting, on the basis of a recent growth law for polycrystalline olivine. We find that the average olivine grain size is greater in the asthenospheric mantle (centimetre-scale grains) than at the crust–mantle boundary (millimetre-scale grains). This grain-size distribution could result in dislocation creep being the dominant deformation mechanism in the upper mantle. However, we suggest that along lithospheric-scale shear zones, a reduction in grain sizes due to localized deformation causes a transition to diffusion creep as the dominant deformation mechanism, causing weakening of the lithosphere and facilitating the initiation of continental rifting.

Numerical model for static chamber measurement of multi-component landfill gas emissions and its application

The quantitative assessment of landfill gas emissions is essential to assess the performance of the landfill cover and gas collection system. The relative error of the measured surface emission of landfill gas may be induced by the static flux chamber technique. This study aims to quantify effects of the size of the chamber, the insertion depth, pressure differential on the relative errors by using an integrated approach of in situ tests, and numerical modeling. A field experiment study of landfill gas emission is conducted by using a static chamber at one landfill site in Xi’an, Northwest China. Additionally, a two-dimensional axisymmetric numerical model for multi-component gas transport in the soil and the static chamber is developed based on the dusty-gas model (DGM). The proposed model is validated by the field data obtained in this study and a set of experimental data in the literature. The results show that DGM model has a better capacity to predict gas transport under a wider range of permeability compared to Blanc’s method. This is due to the fact that DGM model can explain the interaction among gases (e.g., CH4, CO2, O2, and N2) and the Knudsen diffusion process while these mechanisms are not included in Blanc’s model. Increasing the size and the insertion depth of static chambers can reduce the relative error for the flux of CH4 and CO2. For example, increasing the height of chambers from 0.55 to 1.1 m can decrease relative errors of CH4 and CO2 flux by 17% and 18%, respectively. Moreover, we find that gas emission fluxes for the case with positive pressure differential (∆Pin-out) are greater than that of the case without considering pressure fluctuations. The Monte Carlo method was adopted to carry out the statistical analysis for quantifying the range of relative errors. The agreement of the measured field data and predicted results demonstrated that the proposed model has the capacity to quantify the emission of landfill gas from the landfill cover systems.

Experimental and numerical study on the effect of electrohydraulic shock wave on concrete fracturing

In order to apply electrohydraulic shock wave (EHS) technology to oil and gas stimulation or assisted rock fracture, it is necessary to analyze how the crack propagation behavior of the rock subjected to the EHS. For this purpose, experiments and numerical simulations are carried out respectively. In the experiment, the relevant parameters of electrical characteristics and acoustic radiation characteristics were given based on the established discharge platform, and 30 times impacts tests are carried out on cubic concrete. The results show that the corner areas of the upper surface of the concrete are the first to be broken; with the increase of impact time, the shape and number of cracks on the surface of the concrete sample change in two stages. In the first stage, the number of microcracks increased rapidly, the cracks are interconnected, and the existing pores gradually become bigger. In the second stage, the growth rate of the number of microcracks gradually decreases, and the width of the formed cracks gradually increases; the damage variable of the concrete obtained by the acoustic test increases sharply first and then increase slowly throughout the impact test. In the numerical simulation, the history match of the EHS pressure is implemented based on the equivalent explosion method (EEM); a two-dimensional numerical model is established to simulate the interaction process between the EHS and the concrete sample; a three-dimensional TNT-water-concrete numerical model is built to simulate the concrete fracturing. The results show that it is reliable to use the equivalent explosion method to simulate the EHS. The concrete sample subjected to the EHS is affected by four aspects: bubble; transmitted wave and reflected wave; diffraction wave; elastic precursor wave and plastic loading wave. When the element deletion method is used to simulate crack generation, adopting the maximum tensile stress failure criterion can accurately simulate the final distribution of cracks, but it is difficult to simulate the evolution process of cracks under cyclic impact loads.

The Influence of Pore Structure of the Core-Scale Fracture-Controlled Matrix Unit on Imbibition: Model Construction and Definition of the Fractal Coefficient

Abstract Imbibition oil recovery plays an important role in the development of low-permeability fractured reservoirs. However, the effects of the complex pore structure of the matrix on imbibition have not been considered comprehensively at different scales in the scientific literature. This paper reports a study of the mechanisms of influence of different matrix pores on imbibition recovery ratio and defines the concept of a fractal coefficient using the method of combining numerical simulation at the core scale with mathematical methods at a pore scale. A matrix model with different pore fractal dimensions and tortuosity of the capillary was established using Python language programming. Y-type and S-type were used to characterize the fractures, and a two-dimensional fracture-controlled matrix unit core-scale numerical model with complex pore structures was established. Based on phase field theory, an oil-water two-phase imbibition numerical simulation was conducted. Comparisons of numerical simulation results and microscopic analysis indicated that imbibition recovery ratio was 39.28% and 50.94%, respectively. The imbibition law revealed by the numerical simulation results is consistent with the results of the microscopic imbibition experiment, and the imbibition effect of bifurcated fractures was better than that of simple curved fractures. As the pore fractal dimension and tortuosity of the capillary increased, the imbibition recovery ratio decreased. A comparison of results of the mathematical model demonstrated that there was a difference between the pore scale and core scale because the pore fractal dimension and capillary tortuosity changed dynamically with pore structure at the core scale. Thus, a parameter that characterizes the relative change of pore fractal dimension and tortuosity was defined and called the fractal coefficient. When the skeleton particles are 200, 400, and 500, the fractal coefficient were calculated to be 0.625 and 0.6, respectively, indicating that when the pore structure changes, the imbibition recovery ratio should be dominated by capillary tortuosity.

Thermal performance analysis of novel receiver for parabolic trough solar collector

Parabolic trough concentrating solar technology (PTC) is the most deployed technology among all solar thermal technologies. The conventional receivers (heat collection elements, HCEs) suffer from issues of high-technology fabrication, high cost and frequent operational failures. This work proposes a novel parabolic trough receiver design which is facile to fabricate, maintain and repair for long-run solar field operation. The novel receiver is tested experimentally (by indoor heat loss testing) to validate a comprehensive numerical model which is then used to simulate various cases. Effect of inclination angle, absorber temperature, surface emissivity, aperture angle and thermal contact resistance are quantitatively studied by the two-dimensional numerical model incorporating natural convection and surface radiation. The resulting thermal performance is compared with standard evacuated commercial HCEs. Whereas commercial evacuated HCEs cost between 250 and 350 $/m, we show that the novel receiver costs only 42 $/m. Insights from the detailed numerical model are incorporated into a technoeconomic comparison of a solar field raising thermic fluid by 100 K from 566 K and fitted with the novel receiver and the Schott PTR HCE. The difference in cost is about 6%.

Simplified modeling for elastic analysis of a floating body in heave motion

PurposeThis study aims to propose a numerical modeling procedure for response analysis of elastic body floating in water and submitted to regular waves. An equivalent simplified mechanical single-degree-of-freedom system allowing to reproduce the heave movements is first developed, then the obtained lumped characteristics are used for elastic analysis of the floating body in heave motion.Design/methodology/approachFirst, a two-dimensional numerical model of a rigid floating body in a wave tank is implemented under DualSPHysics, an open source computational fluid dynamics (CFD) code based on smoothed particle hydrodynamics method. Then, the obtained results are exploited to derive an equivalent mechanical mass-spring-damper model. Finally, estimated equivalent characteristics are used in a structural finite element modeling of the considered body assuming elastic behavior.FindingsObtained results concerning the floating body displacements are represented and validated using existing experimental data in the literature. Wave forces acting on the body are also evaluated. It was found that for regular waves, it is possible to replace the complex CFD refined model by an equivalent simplified mechanical system which makes easy the use of structural finite element analysis.Originality/valueThe originality of this work lies in the proposed procedure to evaluate the mechanical properties of the equivalent elastic system. This allows to couple two different software tools and to take advantages of their features.

Numerical investigations on the beating behavior of self-excited combustion instability in a hydrogen-fueled Rijke type combustor

Beating, a specific oscillation mode of combustion instability, occurred in a premixed hydrogen fueled Rijke tube was investigated. A two-dimensional transient numerical model for the self-excited combustion instability was developed and well validated. In a beating cycle, the amplitude of pressure oscillations increased to 1400 Pa and then decreased to 70 Pa, exhibiting an obvious feature of low frequency modulation. The joint time-frequency analysis showed that the dominant frequency shifted from 230 Hz to 330 Hz over time at each cycle. To shed lights on the inherent mechanisms of beating instability, the coupling processes between the combustion and flow dynamics were investigated. At each beating cycle, the shapes of flame were relatively stable in growing stage, while strongly fluctuated in transition stage and recovered to stable state in decaying stage. Notably, due to the large amplitude of pressure oscillations, an obvious recirculation zone was formed around the flame and sucked the high temperature exhausted gas to the flame root during the transition stage. Accordingly, the high temperature area was formed around the flame and affected the oscillation mode. By employing the proper orthogonal decomposition analysis, the apparent oscillations at 1 Hz were observed in the modes of heat release rate, velocity vectors and temperature. Later, it was found that with the increase of the amplitude of pressure oscillations, the mass flow rate of air supply at tube inlet dramatically decreased, which reduced the oxygen around the flame and changed the fluctuation mode of heat release rate. The coupling process was also identified by the phase difference and Rayleigh index.

Horizontal Force Required for Subduction Initiation at Passive Margins With Constraints From Slab Detachment

Subduction zones are essential drivers of plate tectonics. However, the processes causing subduction zone initiation (SZI), involving the formation of a new plate boundary, and the forces required remain disputed. Here, we focus on horizontally forced SZI at passive margins and quantify the horizontal force required for SZI with two-dimensional petrological-thermomechanical numerical models. The initial configuration, involving two passive margins bounding a 400 km wide basin with exhumed mantle, is calculated by a numerical rifting simulation to guarantee thermomechanical feasibility and isostatic equilibrium. SZI occurs at one passive margin during convergence of the basin-margin system. SZI is caused by thermal softening due to local shear heating. A local temperature increase of only ca. 50°C is sufficient to cause SZI. Corresponding simulations without shear heating do not show SZI, showing unequivocally that thermal softening controls SZI. We systematically limit the lithospheric deviatoric stress to determine the minimum force required for SZI. A minimum force (per unit length) of ca. 14 TN m−1 is required for SZI; a force magnitude that agrees with independent estimates from mantle convection models. However, for the associated stress limit of 200 MPa the lithosphere is so weak that slab detachment (SD) already occurs at the onset of basin closure in the horizontal, non-subducted region of the subducting plate. Only for stress limits >=300 MPa (yielding a force of ca. 15 TN m−1) subduction of continental crust occurs and SD occurs in the subducted slab. The force required for SZI is a proxy for the effective compressive lithospheric strength. This strength also controls subsequent SD due to tensile slab pull, which increases during subduction, also since our models include the olivine–wadsleyite phase change. Our simulations show a causal link betweeen SZI and subsequent SD: If forces required for SZI are smaller, then the lithosphere is weaker and then SD occurs at shallower levels and corresponding slabs are shorter. Concerning the European Alps, our results imply that if there was no SD since the Europe–Adria collision some 30 Myr ago (as proposed by some studies), then the subducted lithosphere must be considerably strong.

N2O dynamics in the hyporheic zone due to ripple migration

The migration rate of ripples along the streambed has a profound effect on the hyporheic exchange and nitrogen dynamics. However, how the denitrification intermediate N2O is released in mobile bedforms still remain unclear. In this study, the ripple domains are established based on the sediment stability criteria by using the mean channel flow velocity U and the median sediment grain size D50. A two-dimensional numerical model coupling hyporheic flow, ripple migration and N2O transformation is proposed to investigate how ripple celerity affects N2O dynamics in streambeds. The results show that there are different patterns for the release of N2O from migrating ripples with different medium grain sizes D50 (0.06–0.3 mm). N2O can be released via upwelling of anoxic pore water from the deeper area in immobile or slow-mobile ripples. However, rapid ripple migration and the resulting fast vertical flow reversal can suppress the net pore water displacement and lead to the formation of a redox seal, which separates the deeper anoxic area from the above oxic area and inhibits N2O emissions. The magnitude of the nutrients concentration gradient and the N2O flux between these two areas depend only on the dispersive and diffusive transport. Therefore, the controls of N2O emission flux hence shift from the pumping- dominated regime in stable ripples to a grain size dominated regime of the migrating ripples. The possible implications about the effects of hydrodynamic changes due to the migration of ripples are presented. Our results emphasize that knowledge of N2O production-consumption hotspots within streambeds is essential to understand the mechanisms of N2O emissions from the sediment–water interface.

The effect of eccentricity on the collapse behaviour of sandwich pipes

Sandwich pipes (SPs) with adequate strength performance and thermal insulation capacity have become an attractive choice for oil and gas transportation in deep water. The SP has a more complex structural configuration than the traditional single wall pipe. The fabrication process can induce eccentric behaviours of the pipe layers, influencing the external pressure resistance capacity. In this paper, a two-dimensional numerical model of eccentrical sandwich pipes under external pressure is developed using the finite element software ABAQUS. Experimental results are employed to calibrate the numerical models. The verified numerical model combined with a Python scripting program is employed to develop the parametric analysis models. The effects of geometric parameters, material properties, and interlayer friction coefficients with different eccentricities on the SP collapse behavior are investigated. The results show that eccentricity has a significant effect on the collapse of SPs. With the increase of eccentricity, the collapse pressure of SP decreases significantly. Based on the numerical simulations, the optimized design under different geometric parameters, material properties, and interlayer friction coefficients is proposed, reducing the eccentricity effect while optimizing the collapse strength of the sandwich pipe. The present results will support the design and engineering application of deepwater sandwich pipe structures.

Analysis on the Influence of Flood Drainage of Cao’e River Sluice on the Hydrodynamics of Waiguantang River

In order to fully study the impact of Cao’e River Sluice drainage on the external pipe pond and improve the water quality of Shaoxing plain river network, this paper establishes a two-dimensional hydrodynamic model, analyzes the rivers and lakes in Shaoxing plain, and uses the established model to simulate the initial conditions. Through the comparative analysis of the information of the two-dimensional numerical hydrodynamic model and the condition of the river network, we can draw the following conclusions: under normal circumstances, the decline rate of the water surface elevation in Waiguantang river is faster than that in the river network, the overall water surface elevation is relatively stable, and the water surface elevation decreases with the increase of water source distance. The variation range of velocity from the source is large, which is different from the uniform change of water surface elevation. Therefore, the occurrence of flood disaster can be reduced through accurate data analysis.

Numerical simulation of interaction between wave-driven currents and revetment on coral reefs

The stability of a revetment breakwater is vital for the safety of islands and reefs formed with reclaimed sand under the action of a complex marine environment. The interactions in wave-reef-revetment systems are complex and difficult to accurately simulate; in addition, it is difficult to describe the dynamic wave pressures distribution by empirical formula, although these parameters are important for the safety of reefs and revetments; hence, more studies are required. In this study, an investigation of the interaction between the wave-driven current on the reef flat and rear revetment breakwater is performed, and the hydrodynamic pressure on the revetment is discussed. A two-dimensional numerical model is established using the Navier–Stokes equation to explore the interaction and calculate the pressure distribution on the revetment, which is verified by an experiment designed and implemented in a wave flume. The simulation illustrates that the wave-driven current is stratified in the vertical direction, and the velocity at the surface is approximately 2–3 times that of the average value, and the maximum flow velocity can reach 13 m/s. By varying the parameters of the geomorphology of the coral reef, the results suggest that for steeper fore-reef slopes, longer reef flats, and larger relative distances, the peak value of the pressure increases consistently. The detailed and sophisticated hydrodynamic pressure distribution on the revetment is obtained, and the numerical results indicate that the fifth-order polynomial can match the regulation of pulsating pressure at the wave surface with the relative submerged water depth.

Investigation on Thermal Behavior During Pressurization Discharge of Liquid Oxygen Under Different Acceleration Levels

Cryogenic pressurization discharge involves on complex heat exchange and fluid flow issues, and the related thermal physical performance should be comprehensively investigated. In this study, a two-dimensional axisymmetric numerical model is adopted to research the outflow characteristic from a cylindrical liquid oxygen storage tank with the gas injection. The VOF method is utilized to predict the pressurization discharge with 360 K high-temperature gaseous oxygen as the pressurant gas. Validated against the liquid hydrogen discharge experiments, the numerical model is turned out to be proper and acceptable with the calculation errors limited within 20%. On the basis of the numerical model, effect of the flight acceleration level on the tank pressurization and liquid outflow performance are numerically simulated and analyzed, with the gas injection rate of 0.18 kg/s and the liquid outflow rate of 36.0 kg/s. Some valuable conclusions are obtained finally. The present study is significant to the safety flight of launch vehicle and may supply some technical supports for the design of cryogenic propellant system.

Numerical Simulation of Hydrate Decomposition during the Drilling Process of the Hydrate Reservoir in the Northern South China Sea

The process of drilling in natural gas hydrate reservoirs in sea areas involves problems such as hydrate decomposition and wellbore instability. To study the response behaviors of a reservoir during the drilling process, a two-dimensional numerical model of drilling fluid invading a hydrate reservoir in a cylindrical coordinate system was established to simulate the processes of heat and mass transfer, gas–liquid two-phase flow, and hydrate formation and decomposition in the hydrate reservoir during the drilling process. Based on the hydrate reservoir at station W17, Shenhu area of the South China Sea, the physical property response of the hydrate reservoir under different drilling fluid temperatures and salinity values was studied. The simulation results showed that during the drilling process, the temperature and pressure of the reservoir respond rapidly in a large area, further promoting the hydrate decomposition in the reservoir around the wellbore and leading to secondary hydrate formation. Moreover, a high hydrate saturation zone appears near the decomposed hydrate area in the layer without free gas, which corresponds to the low water saturation and high salinity zone. The hydrate decomposition area in the layer with free gas is larger than that without free gas. The increase in the drilling fluid temperature significantly enhances the hydrate decomposition in both layers of the reservoir. The hydrate decomposition near the wellbore under the high drilling fluid temperature will cause a sharp increase in the pressure in the reservoir, leading to the flow of pore fluid into the wellbore. The increase in drilling fluid salinity has little effect on the range of the hydrate decomposition in the reservoir but significantly increases the salinity of the pore water in the layer with free gas. As the drilling fluid temperature increases, the possibility of the gas invasion from the reservoir into the wellbore will be greatly increased at the early stage.