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A darcy-law Based Model for Heat and Moisture Transfer in a Hill Cave

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Fluid Dynamics & Materials Processing 2023年第9期19卷 2345-2359页

作者： Fei Liu Dongliang Zhang Qifu Zhu Qingyong su College of Energy and Building Environment Guilin University of Aerospace TechnologyGuilin541004China College of Mechanical and Electrical Engineering Guilin University of Aerospace TechnologyGuilin541004China

A hill can be regarded as an environmental carrier of heat.Water,rocks and the internal moisture naturally pre-sent in such environment constitute a natural heat accumulator.In the present study,the heat and moisture trans-fer characteristics in a representative hill cave have been simulated via a method relying on the darcy’s law.The simulations have been conducted for both steady and unsteady conditions to discern the inﬂuence of permeability and geometric parameters on the thermal and moisture transfer processes.The reliability of the simulation has been veriﬁed through comparison of the numerical results with the annual observation data.As revealed by the numericalﬁndings,the internal temperature of the hill accumulator is proportional to the permeability,outside surface temperature,overground height,underground constant temperature layer depth,and underground tem-perature of the hill,and it is inversely proportional to the horizontal size of the hill.Moreover,in the considered case,the order of magnitude of the permeability of the hill is contained in the range 10-15–10-13,and displays a certain sensitivity to the rainwater seepage.

关键词： Cave hill thermal and moisture transfer darcy’s law temperatureﬁeld permeability

Motion through spherical droplet with non-homogenous porous layer in spherical container

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Applied Mathematics and Mechanics(English Edition) 2020年第7期41卷 1069-1082页

作者： P.K.YADAV A.TIWARI P.sINGH Department of Mathematics Motilal Nehru National Institute of Technology AllahabadPrayagraj 211004India Department of Mathematics Birla Institute of Technology SciencePilani 333031Rajasthan Department of Mathematics National Institute of Technology PatnaPatna 800005India

The problem of the creeping flow through a spherical droplet with a non-homogenous porous layer in a spherical container has been studied analytically.darcy’s model for the flow inside the porous annular region and the stokes equation for the flow inside the spherical cavity and container are used to analyze the flow.The drag force is exerted on the porous spherical particles enclosing a cavity,and the hydrodynamic permeability of the spherical droplet with a non-homogeneous porous layer is calculated.Emphasis is placed on the spatially varying permeability of a porous medium,which is not covered in all the previous works related to spherical containers.The variation of hydrodynamic permeability and the wall effect with respect to various flow parameters are presented and discussed graphically.The streamlines are presented to discuss the kinematics of the flow.some previous results for hydrodynamic permeability and drag forces have been verified as special limiting cases.

关键词： non-homogenous porous medium stokes equation darcy’s law perme-ability parameter wall effect

The Exponential law Between Dwell Time and the strength of PBX substitute Material

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Acta Mechanica solida sinica 2021年第2期34卷 204-220页

作者： Yizhan Yang Hangjie Lv Jiankang Chen The Faculty of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China

Polymer-bonded sugars(PBss)can be used as a substitute material for polymerbonded explosives(PBXs)due to their ability to simulate the mechanical properties of PBXs.In the process of pressing a PBs,the length of the dwell time has a significant impact on the mechanical properties of the PBs.This reinforcing effect is based on the residual pressure causing the binder to flow and gradually fill each defect.Through the use of darcy5s principle of binder infiltration and viscoelastic theory,an exponential relationship between the compressive strength of PBs and the dwell time has been derived.From the experiments,it was found that the extreme forces that correspond to the compaction stage of the PBs samples with different dwell times were almost the same;this indicates that there is tolerance to damage during the compaction stage.The existence of the compaction stage is related to the brittleness of the PBs.The experimental results showed that as the dwell time increased,the rate of damage evolution of the specimen decreased.

关键词： Polymer-bonded sugars darcy’s law Binder flowing and filling Compressive strength

Hydroelastic Response of VLFs with An Attached submerged Horizontal solid/Porous Plate Under Wave Action

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China Ocean Engineering 2020年第4期34卷 451-462页

作者： FENG Ming-wei sUN Zhao-chen LIANG shu-xiu LIU Bi-jin state Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China school of Civil Engineering and Architecture Xiamen University of TechnologyXiamen 361024China

The hydroelastic responses of a submerged horizontal solid/porous plate attached at the front of a very large rectangular floating structure(VLFs)under wave action has been investigated in the context of linear water wave theory.darcy’s law is adopted to represent energy dissipation in pores.It is assumed that the porous plates are made of material with very fine pores so that the normal velocity across the perforated porous is linearly associated with the pressure drop.In the analytic method,the eigenfunction expansion-matching method(EEMM)for multiple domains is applied to solve the hydrodynamic problem and the elastic equation of motion is solved by the modal expansion method.The performance of the proposed submerged horizontal solid/porous plate can be significantly enhanced by selecting optimal design parameters,such as plate length,horizontal position,submerged depth and porosity.It is concluded that good damping effect can be achieved through installation of solid and porous plate.Porous plate has better damping effect at low frequencies,while solid plate has better damping effect at high frequencies.The optimal ratio of plate length to water depth is 0.25-0.375,and the optimal ratio of submerged depth to water depth is 0.09-0.181.

关键词： VLFs hydroelastic response darcy’s law eigenfunction expansion-matching method submerged horizontal solid/porous plate

On the Application of the Lattice Boltzmann Method to Predict soil Meso seepage Characteristics

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Fluid Dynamics & Materials Processing 2020年第5期16卷 903-917页

作者： Dong Zhou Zhuoying Tan Institute of Civil Engineering Huanghe S&T UniversityZhengzhou450063China school of Civil&Environmental Engineering University of Science and Technology BeijingBeijing100083China

In this study,a two-dimensional approach is elaborated to study with the lattice Boltzmann method(LBM)the seepage of water in the pores of a soil.Firstly,the D2Q9 model is selected to account for the discrete velocity distribution of water flow.In particular,impermeability is considered as macroscopic boundary condition for the left and right domain sides,while the upper and lower boundaries are assumed to behave as pressure boundaries controlled by different densities.The micro-boundary conditions are implemented through the standard rebound strategy and a non-equilibrium extrapolation scheme.Matlab is used for the development of the related algorithm.Finally,the influence of porosity,permeability,osmotic pressure and other factors is assessed with regard to seepage characteristics and the ensuing results are compared with darcy’s law.The computations show that,for fixed initial conditions,the pore structure has a certain influence on the local velocity of seepage,but the overall state is stable,and the average velocity of each layer is the same.The larger the pore passage is,the faster the flow velocity is,and vice versa.For low permeability,the numerical results are consistent with the darcy's law.The greater the pressure difference between the inlet and outlet of seepage,the greater the seepage rate.The relationship between them is linear(yet in good agreement with darcy’s law).

关键词： Lattice Boltzmann method numerical simulation seepage field porosity darcy’s law

A Fractal Orifice-Throat Model for seepage Characteristics of Multiscale Porous Media

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Journal of Mechanics Engineering and Automation 2023年第5期13卷 136-142页

作者： Chunling Wang Yan Gao Lida Zhang Jiaoyan Zhu College of science China Jiliang UniversityHangzhou 310018China

The seepage characteristics of multiscale porous media is of considerable significance in many scientific and engineering fields.The darcy permeability is one of the key macroscopic physical properties to characterize the seepage capacity of porous media.Therefore,based on the statistically fractal scaling law of porous media,fractal geometry is applied to model the multiscale pore structures.And a two-dimensional fractal orifice-throat model with multiscale and tortuous characteristics is proposed for the seepage flow through porous media.The analytical expression for darcy permeability of porous media is derived,which is validated by comparing with available experimental data.The results show that the darcy permeability is significantly influenced by porosity,orifice-throat fractal dimension,minimum to maximum diameter ratio,orifice-throat ratio and tortuosity fractal dimension.The present results are helpful for understanding the seepage mechanism of multiscale porous media,and may provide theoretical basis for unconventional oil and gas exploration and development,porous phase transition energy storage composites,CO2 geological sequestration,environmental protection and nuclear waste treatment,etc.

关键词： Multiscale porous media fractal geometry darcy’s law permeability orifice-throat model.

Analysis of Flow Models for Aerostatic Thrust Bearings with Porous Material

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Journal of Mechanics Engineering and Automation 2020年第6期10卷 181-188页

作者： A.schimpf Y.Gu M.Böhle Technical University of Kaiserslautern Chair for Fluid Mechanics and Fluid MachineryKaiserslautern 67663Germany College of Hydraulic science and Engineering Yangzhou UniversityYangzhou 225009China

The numerical determination of static characteristics of bearings allows a cost-efficient and fast pre-design.In this study,two flow models for aerostatic thrust bearings with pressurized porous material are presented and analyzed.The models are based on the coupling of the Reynolds equation for lubricants(REL)and the determination of pressure drop through porous material by darcy’s law.The simplified model is based on the assumption of a one-dimensional axial flow through porous media.The extended model considers the three-dimensional flow in the porous body.The analysis includes pressurized air from 4 to 9 bar(a)with nominal clearance of 5 to 60μm,Commercial CFD(computational fluid dynamics)software was used to verify the results.The extended model allows a more accurate prediction about the performance in the critical gap range.In total,the results show good agreement with CFD within a short computation time.

关键词： Thrust bearing porous REL darcy’s law CFD.

Methane hydrate accumulation model for the Central Nankai accretionary prism

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Methane hydrate accumulation model for the Central Nankai ac...