Liquid Convection Research Articles

Thermocapillary motion of a solid cylinder near a liquid–gas interface: Janus geometry

In this work, an analytical model is developed for the thermocapillary propulsion of a solid cylinder near a convective liquid–gas interface. Thermocapillarity originates from the temperature-induced surface tension gradients at the liquid–gas interface when the surface temperature of a cylinder residing near the interface differs from the liquid phase. In this work, we consider Janus cylinders with piece-wise constant surface temperatures or heat fluxes. In the former case, we addressed the Gibbs' phenomenon induced by the points of discontinuity. The developed procedure allowed us to study the dynamics of the general case of cylinders with different surface ratios of piece-wise constant temperatures and find the configurations inducing the largest velocities. Most Janus configurations result in motion of the cylinder parallel to the liquid–gas interface. The efficiency of the propulsion parallel to the liquid–gas interface is of the same order of magnitude as the propulsion efficiency of an isotropic cylinder normal to the interface. Considering the emerging interest of scientific community in mechanisms beyond the catalytically induced propulsion, this study may help to shed light on new ways to modulate the propulsion.

Thermal performance of a stack cooling radiator coupled with spray cooling for the future fuel cell electric vehicles

Proton-exchange membrane fuel-cell electric vehicles require an appropriate stack cooling radiator (SCR) system to achieve optimal performance and safe operation. However, SCR cannot achieve high heat rejection under high power demands and hot ambient conditions. Hence, either the SCR needs to be enlarged to manage heat rejection or its ability to reject heat should be enhanced. In this study, a novel low pressure drizzling-aided spray cooling system (SCR-DS) is proposed for the first time. The thermal performance results were compared with those of a high-pressure nozzle-aided spray system (SCR-NS) and a conventional SCR system (SCR-CS). Based on the results, the coolant entry temperature to the stack reduced by up to 1.78 °C, and 2.75 °C when SCR-NS and SCR-DS configurations were active, respectively. Among the various operating factors, the spray cooling performance was significantly influenced by air velocity, spray temperature, and spray flow rate. Furthermore, the experienced mean increments in the heat rejection rate were up to 71.7 % and 123.5 % for the SCD-NS and SCR-DS, respectively, compared to SCR-CS. More importantly, these configurations aid in reducing the size of the SCR by 36.2 % and 45.9 %, respectively, under the same overall heat transfer coefficient conditions. Overall, the SCR-DS configuration was more beneficial than the SCR-NS configuration in terms of thermal performance owing to the slow and steady spray on the SCR surface along with more spray coverage, which aided in better liquid convection and film evaporation.

Analysis of entropy generation and activation energy on a convective MHD Carreau–Yasuda nanofluid flow over a sheet

In recent days, entropy generation has attracted the attention of several researchers due to its applications in manufacturing electronic devices, heat exchangers, conservation of energy, and generation of power. Further, activation energy is an essential requirement in automobile and chemical industries, nuclear reactors, and so on. This paper investigation aims to examine the entropy generation and the mass and energy transfer in the magneto-hydro dynamic movement of convective Carreau-Yasuda nano liquid past a porous stretching sheet with the consequences of activation energy, energy source, and binary chemical reaction. Also, the analysis of the impact of viscous and Joule dissipation in the presence of suction/injection into the Buongiorno model is an essential objective of this study. By introducing a similarity variable, the partial differential equations are altered into a system of ordinary differential equations. Numerical solutions to the modified equations are determined by utilizing a BVP5C MATLAB package. The findings are presented visually for several relevant flow characteristics and explained carefully. The thermophoresis parameter and activation energy parameter optimize the concentration of nanoparticles. These outcomes further indicate that as the larger Brinkmann and permeability parameters the entropy generation is broadened. It is discovered that an augmentation in thermal and solutal Grashof numbers is associated with greater velocity distribution.

MHD mixed convective Maxwell liquid flow passing an unsteady stretched sheet

This study is aimed to investigate the unsteady two-dimensional combined forced and natural convective motion of MHD Maxwell liquid passing a stretched surface. Non-Newtonian feature of the liquid is portrayed with the ‘upper convected Maxwell fluid’ model. A prearranged surface ‘temperature’ at the boundary is considered. ‘Similarity transformations’ are applied to find the self-similar solutions and then the altered ‘equations’ are numerically solved with the help of ‘Runge-Kutta method with shooting technique’. The behaviours of ‘flow’ and ‘heat’ transportation characters for diverse foremost ‘parameters’ are examined and discussed in detail for clear understanding about the non-Newtonian flow features and related thermal field. The interesting behaviours of flow and heat transfer characters warrant further studies of this problem for other type of situations. Due to unsteadiness, ‘velocity and temperature’ are seen to reduce for ‘buoyancy aided and opposed’ flows. Also, it is noted that for ‘buoyancy aided and opposed flows’, liquid velocity diminishes for rising ‘Hartmann number’. The influences of mounting ‘Maxwell parameter’ are to delay fluid velocity for either value of mixed convection parameter. However, for this case temperature is improved. Owing to mixed convection, liquid velocity increases but the temperature reduces within the ‘boundary layer’ area. Here lies the significance of the present study as this result is very much helpful for industrial applications for cooling purpose of different devices.

Abstract WP30: Therapeutic Hypothermia With Thin Liquid Convection is Safe and Feasible in Acute Stroke Patients: The Helping Stroke Patients With ThermoSuit Cooling (SISCO) Pilot Study

Introduction: Animal studies have shown that therapeutic hypothermia of 32-34°C (TH) leads to a drop in infarct size after cerebral artery occlusion. Data suggests that early, rapid TH must be achieved to maximize neuroprotection from ischemic injury. There have been two RCTs of TH in stroke patients, both of which cooled slowly and failed to show the benefit of TH. Objective: The present study assessed the safety and feasibility of the ThermoSuit System (TSS) to induce rapid TH in acute ischemic stroke patients enrolled in the SISCO pivotal phase I trial. The TSS circulates cold water directly over the patient’s skin to achieve TH and has previously demonstrated significantly faster cooling than other methods. Methods: Eligible stroke patients were enrolled with an NIHSS > 5, less than 8 hours from LKW, or who met the extended window thrombectomy criteria. Patients were sedated and intubated according to protocols. Cooling was initiated by circulating ice-cold water (0-8°C) through the TSS. The patients were cooled until the core temperature reached 34-33°C, and the suit was removed. Temperature was maintained at 32°C to 34°C for 24 hours following the cooling induction using a conventional cooling blanket. Criteria for study success were defined as 1) at least 50% of the patients achieving 32-34°C within 1 hour; 2) NIHSS and mRS scores at 90 days post-stroke were not statistically worse than historical controls; 3) no significant increase in adverse event rates in cooled subjects vs. historical controls. RESULTS 14 subjects were enrolled, and 13 were cooled. 2 patients were excluded due to treatment delays and 1 due to missing outcome data, leaving 10 patients available for complete analysis. The average NIHSS on admission was 18, and the average patient age was 65. 7 patients had an LVO in the anterior circulation and 3 had posterior circulation strokes. All study success criteria were met. The median cooling time to 34°C was 40 minutes. The rates of unacceptable outcomes at 90 days (mRS >3) were 45% in 1314 published historical controls but only 10% in cooled subjects. Conclusion: The TSS is a safe and effective tool for rapid TH in ischemic stroke patients. Further studies are warranted to assess whether this cooling method is neuroprotective for these patients.

Manipulation of Convection Using Infrared Light Emitted from Human Hands.

Control of convection plays an important role in heat transfer regulation, bio/chemical sensing, phase separation, etc. Current convection controlling systems generally depend on engineered energy sources to drive and manipulate the convection, which brings additional energy consumption into the system. Here the use of human hand as a natural and sustainable infrared (IR) radiation source for the manipulation of liquid convection is demonstrated. The fluid can sense the change of the relative position or the shape of the hand with the formation of different convection patterns. Besides the generation of static complex patterns, dynamic manipulation of convections can also be realized via moving of hand or finger. The use of such sustainable convections to control the movement of a floating "boat" is further achieved. The use of human hands as the natural energy sources provides a promising approach for the manipulation of liquid convection without the need of extra external energy, which may be further utilized for low-cost and intelligent bio/chemical sensing and separation.

Onset of Rayleigh-Bénard convection in dielectric liquids with electric conduction

Onset of Rayleigh-Bénard convection in dielectric liquids with electric conduction

Modeling of temperature convection in microtubes under point heating: dependence of convection velocity on tilt angle

This paper presents the results of a study of the dependence of the convection velocity of a liquid in a microtube on the angle of inclination during point heating. This study utilizes a previously prepared finite-volume mesh of a cone-shaped microtube for use within the OpenFOAM software package. A detailed analysis and description of the mathematical model and a series of computational experiments using the built-in buoyantBoussinesqPimpleFoam solver are performed. An important step in this paper is the post-processing of the results obtained from a series of computational experiments. The paper provides a detailed description of the features of the data processing carried out for direct quantitative comparison of the results obtained in the individual experiments of the series. In the conducted computational experiments, quantitative data were obtained to reveal the dependence of the liquid convection velocity in a microtube on the angle of inclination during spot heating. From the obtained results, a significant influence of the inclination angle on the convection velocity was revealed, which can serve as a solution for the problems of optimization of mixing processes in microscale systems in the future.

A Unified Approach to Two-Dimensional Brinkman-Bénard Convection of Newtonian Liquids in Cylindrical and Rectangular Enclosures.

A unified model for the analysis of two-dimensional Brinkman-Bénard/Rayleigh-Bénard/ Darcy-Bénard convection in cylindrical and rectangular enclosures (CE/RE) saturated by a Newtonian liquid is presented by adopting the local thermal non-equilibrium (LTNE) model for the heat transfer between fluid and solid phases. The actual thermophysical properties of water and porous media are used. The range of permissible values for all the parameters is calculated and used in the analysis. The result of the local thermal equilibrium (LTE) model is obtained as a particular case of the LTNE model through the use of asymptotic analyses. The critical value of the Rayleigh number at which the entropy generates in the system is reported in the study. The analytical expression for the number of Bénard cells formed in the system at the onset of convection as a function of the aspect ratio, So, and parameters appearing in the problem is obtained. For a given value of So it was found that in comparison with the case of LTE, more number of cells manifest in the case of LTNE. Likewise, smaller cells form in the DBC problem when compared with the corresponding problem of BBC. In the case of RBC, fewer cells form when compared to that in the case of BBC and DBC. The above findings are true in both CE and RE. In other words, the presence of a porous medium results in the production of less entropy in the system, or a more significant number of cells represents the case of less entropy production in the system. For small and finite So, the appearance of the first cell differs in the CE and RE problems.

Fluorinated Graphene Thermally Conductive Hydrogel with a Solid-Liquid Interpenetrating Heat Conduction Network.

Hydrogels with excellent mechanical flexibility are widely used in flexible electronic devices. However, it is difficult to meet further applications of high-power integrated flexible electronics as a result of their low thermal conductivity. Herein, highly thermally conductive composite hydrogels with a solid-liquid interpenetrating thermal conductivity network are constructed by aromatic polyamide nanofibers (ANF) and fluorinated graphene (FG) reinforced poly(vinyl alcohol) (PVA) and cross-linked by tannic acid (TA) solution immersion to obtain a hydrogel with a double cross-linked network. The PVA-ANF-FG3T-11.1% composite hydrogel exhibits good mechanical properties compared to PVA-ANFT, with a tensile modulus of up to 0.89 MPa, a tensile strength of up to 1.23 MPa, and an energy of rupture of up to 3.45 MJ cm-3, which is mainly attributed to the multihydrogen bonding interactions in the composite hydrogel. In addition, the friction coefficient of the PVA-ANF-FG3T-11.1% composite hydrogel is 0.178, making it suitable for use in high-friction coefficient applications. The thermal conductivity of the PVA-ANF-FG3T-11.1% composite hydrogel is 1.42 W m-1 K-1, which is attributed to the synergistic effect of the solid thermal conductivity network and the liquid convection network, resulting in a high thermal conductivity of the composite hydrogel. The high thermal conductivity of the PVA-ANF-FG3T-11.1% composite hydrogel shows great potential for flexible wearable electronics and cooling paste applications.

Anisotropic Darcy–Brinkman Magnetic Fluid Convection under the Influence of a Time-Dependent Sinusoidal Magnetic Field

The impact of the sinusoidal mode of a magnetic field involving time fluctuations on the threshold of the ferromagnetic smart liquid convection in a saturated permeable medium is investigated using the regular perturbation technique. The Darcy–Brinkman model with anisotropic permeability is used to describe the flow through porous media. The thermal anisotropy is implemented in the energy equation. The problem might be useful in thermal engineering applications such as dynamic loudspeakers and computer hard discs and in medical applications like the treatment of tumor cells and the cell separation, to name a few. The regular perturbation technique is based on the minimum amplitude of a magnetic field modulation, and the onset criterion is dealt with in terms of a correction in the critical Rayleigh number and wavenumber. The thermal Rayleigh number correction depends on the magnetic field modulation frequency, magnetic force, anisotropies, porosity, and Prandtl number. At moderate values of the magnetic field modulation frequency, the impact of various physical factors is perceived to be noteworthy. The influences of the magnetic mechanism, Prandtl number, porosity parameter, and Brinkman number are shown to augment the destabilizing effect of the magnetic field modulation for moderate values of the frequency of a modulation. However, the destabilizing effect of the magnetic field modulation is diminished due to an increase in the values of the mechanical anisotropy parameter and thermal anisotropy parameter. The study reveals that the effect of the magnetic field modulation could be exploited to control the convective instability in an anisotropic porous medium saturated by a ferromagnetic fluid.

Air Purification Study Based on the Adhesion Effect between Low-Curvature Liquid Surfaces and Air Convection Friction

Rapid urbanization and industrialization have heightened concerns about air quality worldwide. Conventional air purification methods, reliant on chemicals or energy-intensive processes, fall short in open spaces and in combating emerging pollutants. Addressing these limitations, this study presents a novel water-film air purification prototype leveraging the adhesion between low-curvature liquid surfaces and air convection friction. Uniquely designed, this prototype effectively targets toxic gases (e.g., formaldehyde, SO2, NO2) and particulate matter (such as PM2.5) while allowing continuous airflow. This research explores the adhesion and sedimentation capabilities of a low-curvature water solution surface under convection friction, reducing the surface energy to remove airborne pollutants efficiently. The prototype was able to reduce the initial concentration in a 30 m³ chamber within 180 min by 91% for formaldehyde, 78% for nitrogen dioxide (NO2), 99% for sulfur dioxide (SO2), and 96% for PM2.5. Experimentally validated indicators—decay constants, CADR, and purification efficiency—enable a comprehensive evaluation of the purification device, demonstrating its efficacy in mitigating air pollution. This innovative design, which is cost-effective due to its use of easily accessible components and water as the primary medium, indicates strong potential for large-scale deployment. This study points to an environmentally friendly and economical approach to air purification, shedding light on a promising direction for enhancing indoor air quality. Further optimization and exploration of diverse pollutants and environmental conditions will propel the practical applications of this pioneering technology.

Unsteady double-diffusive convective flow of an Oldroyd-B hybrid nanofluid in a porous medium with cross-diffusion effects

This research focuses on convection driven by a thermal gradient and a concentration gradient in an Oldroyd-B hybrid nanofluid saturated by a highly permeable layer with cross-diffusion effects. The Buongiorno model is implemented with the diversity of thermophoresis and Brownian diffusion. Using linear stability theory, an analytical expression for thermal Rayleigh number is obtained at the onset of binary liquid convection. For the nonlinear analysis, the governing PDEs are altered into ODEs by making use of similarity transformations. The rate of heat and mass transfer are calculated with the help of the built-in function NDSolve in computational tool MATHEMATICA 12.0. The numerical results are offered for the base fluid as ethylene glycol with hybrid copper and silver nanoparticles. The graphical illustrations are described to understand the impact of all the emerging parameters on the onset of convective phenomenon. Hybrid nanofluid is found to be more stable in comparison with single particle nanofluid. As far as technological applications are concerned, mono nanofluid could be replaced by hybrid nanofluid and this can be stated as a novelty of the article. We have observed that the heat and mass transfer profile is boosted up for increasing viscoelastic parameters i.e. stress relaxation and strain retardation parameters, solutal Rayleigh number and Prandtl number. In addition, the heat transfer displays an increasing nature toward the higher amounts of nanoparticle volume fraction.

CFD modelling of the non-isobaric evaporation of cryogenic liquids in storage tanks

A new CFD model relevant to non-isobaric cryogen evaporation has been developed. It considers the heat influx, from the surroundings to the liquid and vapour phases, and the heat transfer between the phases. The phase change is modelled considering two contributions: an interfacial energy balance far from the tank wall, and by direct wall-to-liquid conduction near the wall. The model provides well resolved liquid and vapour temperature and velocity profiles, as well as pressure build-up and evaporation rates. It shows that below the vapour-liquid interface, liquid natural convection is dampened by thermal stratification, which is driven by the increase of the interfacial temperature due to increase in pressure. The pressure build-up is mainly governed by the heating of the vapour, particularly at the beginning of the evaporation. The model was used to analyse liquid velocity profiles for two different sets of experimental data for evaporation of liquid nitrogen by optimizing empirical parameters, namely the wall heat partitioning fraction and the overall heat transfer coefficients. The results show that a large fraction of the vapour heat ingress is not transferred to the vapour phase bulk. Instead, it is transported through the walls and transferred to the liquid at the liquid-vapour-wall contact point, driving phase change. Heat conduction from the walls to the interface has a significant effect, even for low heat fluxes, and cannot be neglected.

Strong coupling of flow structure and heat transport in liquid metal thermal convection

A typical feature of thermal convection is the formation of large-scale flow (LSF) structures of the order of system size. How this structure affects global heat transport is an important issue in the study of thermal convection. We present an experimental study of the coupling between the flow structure and heat transport in liquid metal convection with different degrees of spatial confinement, characterized by the aspect ratio $\varGamma$ of the convection cell. Combining measurements in two convection cells with $\varGamma =1.0$ and 0.5, the study shows that a large-scale circulation (LSC) transports ${\sim }35\,\%$ more heat than a twisted LSC. It is further found that when the LSF is in the form of the LSC state, the system is in a fully developed turbulence state with a $Nu\sim Ra^{0.29}$ scaling for the heat transport. However, the twisted LSC state with a heat transport scaling of $Nu\sim Ra^{0.37}$ appears when the system is not in the fully developed turbulence state. Bistability is observed when the system evolves from the twisted-LSC-dominated to the LSC-dominated state.

Three-dimensional flow structures in turbulent Rayleigh–Bénard convection at low Prandtl number Pr = 0.03

In this paper we report on an experimental study focusing on the manifestation and dynamics of the large-scale circulation (LSC) in turbulent liquid metal convection. The experiments are performed inside a cylinder of aspect ratio $\varGamma = 0.5$ filled with the ternary alloy GaInSn, which has a Prandtl number of $Pr = 0.03$ . The large-scale flow structures are classified and characterized at Rayleigh numbers of ${Ra} = 9.33 \times 10^6, 5.31 \times 10^7$ and $6.02 \times 10^8$ by means of the contactless inductive flow tomography which enables the full reconstruction of the three-dimensional (3-D) flow structures in the entire convection cell. This is complemented with the multi-thermal-probe method for capturing the azimuthal temperature variation induced by the LSC at the sidewall. We use proper orthogonal decomposition (POD) to identify the dominating modes of the turbulent convection. The analysis reveals that a single-roll structure of the LSC alternates in short succession with double-roll structures or a three-roll structure. This is accompanied by dramatic fluctuations of the Reynolds number, whose instantaneous values can deviate by more than 50 % from the time-average value. No coherent oscillations are observed, whereas a correlation analysis indicates a residual contribution of the torsion and sloshing modes. Results of the POD analysis suggest a stabilization of the single-roll LSC with increasing $Ra$ at the expense of flow structures with multiple rolls. Moreover, the relative lifetime of all identified flow states, measured in units of free-fall times, increases with rising $Ra$ .

Stability of magnetohydrodynamics free convective micropolar thermal liquid movement over an exponentially extended curved surface

Micro polar fluids have a wide variety of applications in biomedical, manufacturing, and technical activities, such as nuclear structures, biosensors, electronic heating and cooling, etc. The aim of this study is to investigate the properties of heat transfer on a magnetohydrodynamic free convection movement of micro polar fluid over an exponentially stretchable curved surface. The flow is non-turbulent and steady. The effects of Joule heating, varying thermal conductivity, irregular heat reservoir, and non-linear radiation are anticipated. The modelled PDEs are converted to ODEs via transformation, and the integration problems are then addressed using ND-Solve method along with bvp4c package. It is observed that velocity is reduced and the micro rotation field is increased as the micro rotation parameter is increased. It is witnessed that the temperature of the fluid enhances as the Eckert number is augmented. The velocity is increasing function of the curvature parameter while the decreases with increasing magnetic factor. The distribution of temperature is improved by a rise in temperature-dependent thermal conductivity characteristic. It is investigated that as the values of temperature ratio, Prandtl number, and the Biot number are increased the temperature distribution is enhanced. For the stability of the numerical results, the mean square residue error (MSRE) and total mean square residue error (TMSRE) are computed. For the confirmation of the present analysis, a comparison is done with the published study and excellent settlement is found.

Modified thermal and solutal fluxes through convective flow of Reiner-Rivlin material

Heat transport in mixed convection Reiner-Rivlin liquid flow due to stretching cylinder is addressed. Cattaneo-Christov double diffusive relation is utilized to discuss heat and solutal transport features. Variable thermal conductivity and mass diffusivity impacts are incorporated. Adequate transformations are used to reduce non-linear differential expressions for dimensionless expressions. The given non-dimensional expressions are solved through implementation of Optimal homotopy analysis technique (OHAM). Physical features of fluid flow, concentration and temperature against influential parameters are examined. Clearly higher mixed convection parameter boost the liquid flow. Decay in temperature is detected against thermal relaxation time. Similar impact of temperature is witnessed by curvature and thermal conductivity variables. Velocity enhances against Reiner-Rivlin material variable. Decline in concentration is detected for higher Schmidt number. Concentration boosts against mass diffusivity parameter. Higher solutal relaxation time parameter leads to decline concentration. Reduction in temperature is noticed for Prandtl number whereas opposite behavior witnessed for heat transport rate. An increment in mass transport rate occurs for mass diffusivity and solutal relaxation time variables.

On the free convection of magneto-micropolar fluid in association with thermal radiation and chemical reaction and optimized heat transfer rate using response surface methodology

An analysis is carried out for the free convection of magneto-micropolar liquid via a stretching surface for the inclusion of thermal radiation and chemical reaction. The transverse magnetic field is employed on the normal direction of flow with the impact of Peclet number relating to thermal and solutal transfer profiles. Referring to the current applications in several engineering problems, industrial applications, and more importantly the peristaltic pumping processes, blood flow phenomena, etc. the role of micropolar fluid is significant. Therefore, the objective of thismodel is to develop by incorporating thermal radiation which has several applications in aforesaid areas. However, the proposed model is solved analytically using the differential transform method (DTM) and prior to that transformation to ordinary system is obtained by using similarity transformations. The characteristic of various physical components associated with the governing equations is deployed graphically. The analysis of these parameters is described briefly in the discussion section. Further, a statistical approach response surface methodology (RSM) is used to optimize the heat transfer rate for the factors such as magnetic parameter, thermal radiation, and Peclet number.

Effects of seasonal rainfall variations on the hydrothermal state and thermal stability of the permafrost active layer in the central Qinghai-Tibet Plateau of China

Rainfall significantly impacts the hydrothermal state and thermal stability of the permafrost active layer by modifying surface energy boundary conditions. The quantitative characterization of hydrothermal changes in the Qinghai-Tibet Plateau has long been a crucial issue, yet the mechanisms underlying the effects of seasonal rainfall on the hydrothermal state within the permafrost active layer remain poorly understood. Therefore, this study investigated the influence of seasonal rainfall variations on the hydrothermal state within the permafrost active layer based on a water-vapour-heat coupled model that optimises the surface energy balance boundary conditions. The results show that regardless of whether the spring rainfall changes or not, the Bowen ratio is >1, indicating that the main energy exchange mode between the atmosphere and surface is sensible heat flux. But following the increase in rainfall in summer and autumn, the Bowen ratio is <1, indicating that the main energy exchange mode is latent heat flux. Meanwhile, increased seasonal rainfall leads to an increase in liquid water flux and a decrease in water vapour flux, whereas decreased seasonal rainfall leads to the opposite trend. Heat conduction, water vapour thermal convection, and water vapour diffusion latent heat decrease with increasing rainfall in various seasons. However, liquid water thermal convection increases with increasing rainfall during various seasons. Seasonal rainfall variations ultimately affect permafrost thermal stability by influencing water-vapour migration and energy changes within the permafrost active layer. Among them, the active layer thickness remains basically unchanged after the spring rainfall increases by 2.0 times, whereas it decreases by 4 and 6 cm after the summer and autumn rainfall increase by 1.5 and 2.0 times, respectively. Additionally, when the rainfall during spring, summer, and autumn decreases by 2.0, 1.5, and 2.0 times, respectively, the active layer thickness increases by 7, 6, and 3 cm, respectively. Therefore, increased seasonal rainfall can alleviate permafrost degradation. Otherwise, it is unfavourable for the preservation of permafrost thermal stability.