The study considers numerical findings regarding magneto-thermosolutal-aided natural convective flow of alumina/water-based nanofluid filled in a non-Darcian porous horizontal concentric annulus.Two equations are assu...The study considers numerical findings regarding magneto-thermosolutal-aided natural convective flow of alumina/water-based nanofluid filled in a non-Darcian porous horizontal concentric annulus.Two equations are assumed to evaluate the thermal fields in the porous medium under Local Thermal Non-Equilibrium(LTNE)conditions,along with the Darcy-Brinkman-Forchheimer model for the flow.By imposing distinct and constant temperatures and concentrations on both internal and external cylinders,thermosolutal natural convection is induced in the annulus.We apply the finite volume method to solve the dimensionless governing equations numerically.The thermal conductivity and viscosity of the nanofluid mixture are determined utilizing Corcione’s empirical correlations,incorporating the effects of Brownian diffusion of nanoparticles.Steady-state findings are provided for a range of significant parameters,including buoyancy ratio(N=1 to 5),Lewis(Le=0 to 10),Rayleigh(Ra=102 to 105),Hartmann(Ha=0 to 50),and heat generation in the nanofluid and solid phases(Q=0 to 20)when the nanofluid flow is driven by aiding thermal and mass buoyancies at given porous medium characteristics(porosity(ε),Darcy number(Da),porous interfacial heat transfer coefficient(H),and thermal conductivity ratio(γ),to assess the thermosolutal convective circulation beside heat and solutal transfer rates in the annulus.The results reveal that internal heat generation significantly modifies the heat transport mechanism,initially reducing and then enhancing heat transfer rates as Q increases.Interestingly,increasing Le reduces heat transfer at low Q but promotes it when Q>5,while mass transfer consistently increases with Le.The magnetic field represses heat transfer in the absence of internal heat but enhances it when internal heat is present.展开更多
In this study,a powerful thermo-hydro-mechanical(THM)coupling solution scheme for saturated poroelastic media involving brittle fracturing is developed.Under the local thermal non-equilibrium(LTNE)assumption,this sche...In this study,a powerful thermo-hydro-mechanical(THM)coupling solution scheme for saturated poroelastic media involving brittle fracturing is developed.Under the local thermal non-equilibrium(LTNE)assumption,this scheme seamlessly combines the material point method(MPM)for accurately tracking solid-phase deformation and heat transport,and the Eulerian finite element method(FEM)for effectively capturing fluid flow and heat advection-diffusion behavior.The proposed approach circumvents the substantial challenges posed by large nonlinear equation systems with the monolithic solution scheme.The staggered solution process strategically separates each physical field through explicit or implicit integration.The characteristic-based method is used to stabilize advection-dominated heat flows for efficient numerical implementation.Furthermore,a fractional step approach is employed to decompose fluid velocity and pressure,thereby suppressing pore pressure oscillation on the linear background grid.The fracturing initiation and propagation are simulated by a rate-dependent phase field model.Through a series of quasi-static and transient simulations,the exceptional performance and promising potential of the proposed model in addressing THM fracturing problems in poro-elastic media is demonstrated.展开更多
In the present study,the thermal performance of metal foam heat sink was numerically investigated by adopting the local thermal non-equilibrium(LTNE)model and local thermal equilibrium(LTE)model.Temperature field dist...In the present study,the thermal performance of metal foam heat sink was numerically investigated by adopting the local thermal non-equilibrium(LTNE)model and local thermal equilibrium(LTE)model.Temperature field distributions and temperature difference field distributions of solid and fluid phases were presented.Detailed thermal performance comparisons based on the LTE and LTNE models were evaluated by considering the effects of the relevant metal foam morphological and channel geometrical parameters.Results indicate that a distinct temperature difference exists between the solid and fluid phases when the LTNE effect is pronounced.The average Nusselt numbers predicted by both the LTE and LTNE models are approaching with the increase of porosity,pore density,Reynolds number,large thermal conductivity ratio,and large aspect ratio.This is attributed to the significant reduction of the interstitial convective thermal resistance between the solid and fluid phases,as a result,the LTE model can replace the LTNE model for thermal modeling in these conditions.In addition,the overall thermal performance assessment of metal foam heat sink is compared with the non-porous heat sink,and it shows that the thermal performance factor of metal foam heat sink is approximately two times of the non-porous heat sink.展开更多
The heat transfer through a concave permeable fin is analyzed by the local thermal non-equilibrium(LTNE)model.The governing dimensional temperature equations for the solid and fluid phases of the porous extended surfa...The heat transfer through a concave permeable fin is analyzed by the local thermal non-equilibrium(LTNE)model.The governing dimensional temperature equations for the solid and fluid phases of the porous extended surface are modeled,and then are nondimensionalized by suitable dimensionless terms.Further,the obtained nondimensional equations are solved by the clique polynomial method(CPM).The effects of several dimensionless parameters on the fin's thermal profiles are shown by graphical illustrations.Additionally,the current study implements deep neural structures to solve physics-governed coupled equations,and the best-suited hyperparameters are attained by comparison with various network combinations.The results of the CPM and physicsinformed neural network(PINN)exhibit good agreement,signifying that both methods effectively solve the thermal modeling problem.展开更多
Phase change energy storage technology has great potential for enhancing the efficient conversion and storage of energy.While triply periodic minimal surface(TPMS)structures have shown promise in improving heat transf...Phase change energy storage technology has great potential for enhancing the efficient conversion and storage of energy.While triply periodic minimal surface(TPMS)structures have shown promise in improving heat transfer,research on their application in phase change heat transfer remains limited.This paper presents numerical simulations of composite phase change materials(PCMs)featuring TPMS skeletons,specifically gyroid,diamond,primitive,and I-graph and wrapped package-graph(I-WP)utilizing the lattice Boltzmann method(LBM).A comparative analysis of the effects of four TPMS skeletons on enhancing the phase change process reveals that the PCM containing the gyroid skeleton melts the fastest,with a complete melting time of 24.1%shorter than that of the PCM containing the I-WP skeleton.The PCM containing the gyroid skeleton is further simulated to explore the effects of the Rayleigh(Ra)number,Prandtl(Pr)number,and Stefan(Ste)number on the melting characteristics.Notably,the complete melting time is reduced by 60.44%when Ra is increased to 10^(6)compared to the case with Ra at 10^(4).Increasing the Pr number accelerates the migration of the mushy zone,resulting in fast melting.Conversely,the convective heat transfer effect from the heating surface decreases as the Ste number increases.The temperature differences caused by the local thermal non-equilibrium(LTNE)effect over time are significant and complex,with peaks becoming more pronounced nearer the heating surface.This study intends to provide theoretical support for the further development of TPMS skeletons in enhancing the phase change process.展开更多
An analysis is performed to study the influence of local thermal nonequilibrium(LTNE)on unsteadyMHDlaminar boundary layer flowof viscous,incompressible fluid over a vertical stretching plate embedded in a sparsely pac...An analysis is performed to study the influence of local thermal nonequilibrium(LTNE)on unsteadyMHDlaminar boundary layer flowof viscous,incompressible fluid over a vertical stretching plate embedded in a sparsely packed porous medium in the presence of heat generation/absorption.The flow in the porous medium is governed by Brinkman-Forchheimer extended Darcy model.A uniform heat source or sink is presented in the solid phase.By applying similarity analysis,the governing partial differential equations are transformed into a set of time dependent non-linear coupled ordinary differential equations and they are solved numerically by Runge-Kutta Fehlberg method along with shooting technique.The obtained results are displayed graphically to illustrate the influence of different physical parameters on the velocity,temperature profile and heat transfer rate for both fluid and solid phases.Moreover,the numerical results obtained in this study are compared with the existing literature in the case of LTE and found that they are in good agreement.展开更多
Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale,a new two-phase mixture...Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale,a new two-phase mixture model is developed by incor-porating the local thermal non-equilibrium effect.Considering the low-pressure and high overload working conditions of hypersonic flying,the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled,saturated and super-heated states of water coolant under varying saturation pressures.After the validation of the model,transient simulations for different external factors,includ-ing spatially-varied heat flux,coolant mass flux,time-dependent external pressure and aircraft acceleration are conducted.The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure,and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage.The motion of flying has a large influence on the cooling effect,as the inertial force could change the flow pattern of the fluid inside significantly.The comparison of the results from 2-D and 3-D simulations sug-gests that 3-D simulation shall be conducted for practical application of transpiration cooling,as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.展开更多
基金The authors extend their appreciation to the Deanship of Scientific Research at Northern Border University,Arar,Saudi Arabia,for funding this research work through the project number NBU-FFR-2025-2193-15.
文摘The study considers numerical findings regarding magneto-thermosolutal-aided natural convective flow of alumina/water-based nanofluid filled in a non-Darcian porous horizontal concentric annulus.Two equations are assumed to evaluate the thermal fields in the porous medium under Local Thermal Non-Equilibrium(LTNE)conditions,along with the Darcy-Brinkman-Forchheimer model for the flow.By imposing distinct and constant temperatures and concentrations on both internal and external cylinders,thermosolutal natural convection is induced in the annulus.We apply the finite volume method to solve the dimensionless governing equations numerically.The thermal conductivity and viscosity of the nanofluid mixture are determined utilizing Corcione’s empirical correlations,incorporating the effects of Brownian diffusion of nanoparticles.Steady-state findings are provided for a range of significant parameters,including buoyancy ratio(N=1 to 5),Lewis(Le=0 to 10),Rayleigh(Ra=102 to 105),Hartmann(Ha=0 to 50),and heat generation in the nanofluid and solid phases(Q=0 to 20)when the nanofluid flow is driven by aiding thermal and mass buoyancies at given porous medium characteristics(porosity(ε),Darcy number(Da),porous interfacial heat transfer coefficient(H),and thermal conductivity ratio(γ),to assess the thermosolutal convective circulation beside heat and solutal transfer rates in the annulus.The results reveal that internal heat generation significantly modifies the heat transport mechanism,initially reducing and then enhancing heat transfer rates as Q increases.Interestingly,increasing Le reduces heat transfer at low Q but promotes it when Q>5,while mass transfer consistently increases with Le.The magnetic field represses heat transfer in the absence of internal heat but enhances it when internal heat is present.
基金supported by National Natural Science Foundation of China(Grant No.42377149)the Research Grants Council of Hong Kong(General Research Fund Project No.17202423).
文摘In this study,a powerful thermo-hydro-mechanical(THM)coupling solution scheme for saturated poroelastic media involving brittle fracturing is developed.Under the local thermal non-equilibrium(LTNE)assumption,this scheme seamlessly combines the material point method(MPM)for accurately tracking solid-phase deformation and heat transport,and the Eulerian finite element method(FEM)for effectively capturing fluid flow and heat advection-diffusion behavior.The proposed approach circumvents the substantial challenges posed by large nonlinear equation systems with the monolithic solution scheme.The staggered solution process strategically separates each physical field through explicit or implicit integration.The characteristic-based method is used to stabilize advection-dominated heat flows for efficient numerical implementation.Furthermore,a fractional step approach is employed to decompose fluid velocity and pressure,thereby suppressing pore pressure oscillation on the linear background grid.The fracturing initiation and propagation are simulated by a rate-dependent phase field model.Through a series of quasi-static and transient simulations,the exceptional performance and promising potential of the proposed model in addressing THM fracturing problems in poro-elastic media is demonstrated.
基金supported by the National Natural Science Foundation of China(No.51676208 and No.51906257)the fundamental research funds of central universities(No.18CX07012A and No.19CX05002A)the Major Program of the Natural Science Foundation of Shandong Province(No.ZR2019ZD11).
文摘In the present study,the thermal performance of metal foam heat sink was numerically investigated by adopting the local thermal non-equilibrium(LTNE)model and local thermal equilibrium(LTE)model.Temperature field distributions and temperature difference field distributions of solid and fluid phases were presented.Detailed thermal performance comparisons based on the LTE and LTNE models were evaluated by considering the effects of the relevant metal foam morphological and channel geometrical parameters.Results indicate that a distinct temperature difference exists between the solid and fluid phases when the LTNE effect is pronounced.The average Nusselt numbers predicted by both the LTE and LTNE models are approaching with the increase of porosity,pore density,Reynolds number,large thermal conductivity ratio,and large aspect ratio.This is attributed to the significant reduction of the interstitial convective thermal resistance between the solid and fluid phases,as a result,the LTE model can replace the LTNE model for thermal modeling in these conditions.In addition,the overall thermal performance assessment of metal foam heat sink is compared with the non-porous heat sink,and it shows that the thermal performance factor of metal foam heat sink is approximately two times of the non-porous heat sink.
基金funding this work through Small Research Project under grant number RGP.1/141/45。
文摘The heat transfer through a concave permeable fin is analyzed by the local thermal non-equilibrium(LTNE)model.The governing dimensional temperature equations for the solid and fluid phases of the porous extended surface are modeled,and then are nondimensionalized by suitable dimensionless terms.Further,the obtained nondimensional equations are solved by the clique polynomial method(CPM).The effects of several dimensionless parameters on the fin's thermal profiles are shown by graphical illustrations.Additionally,the current study implements deep neural structures to solve physics-governed coupled equations,and the best-suited hyperparameters are attained by comparison with various network combinations.The results of the CPM and physicsinformed neural network(PINN)exhibit good agreement,signifying that both methods effectively solve the thermal modeling problem.
基金supported by the National Natural Science Foundation of China(Grant No.51976111).
文摘Phase change energy storage technology has great potential for enhancing the efficient conversion and storage of energy.While triply periodic minimal surface(TPMS)structures have shown promise in improving heat transfer,research on their application in phase change heat transfer remains limited.This paper presents numerical simulations of composite phase change materials(PCMs)featuring TPMS skeletons,specifically gyroid,diamond,primitive,and I-graph and wrapped package-graph(I-WP)utilizing the lattice Boltzmann method(LBM).A comparative analysis of the effects of four TPMS skeletons on enhancing the phase change process reveals that the PCM containing the gyroid skeleton melts the fastest,with a complete melting time of 24.1%shorter than that of the PCM containing the I-WP skeleton.The PCM containing the gyroid skeleton is further simulated to explore the effects of the Rayleigh(Ra)number,Prandtl(Pr)number,and Stefan(Ste)number on the melting characteristics.Notably,the complete melting time is reduced by 60.44%when Ra is increased to 10^(6)compared to the case with Ra at 10^(4).Increasing the Pr number accelerates the migration of the mushy zone,resulting in fast melting.Conversely,the convective heat transfer effect from the heating surface decreases as the Ste number increases.The temperature differences caused by the local thermal non-equilibrium(LTNE)effect over time are significant and complex,with peaks becoming more pronounced nearer the heating surface.This study intends to provide theoretical support for the further development of TPMS skeletons in enhancing the phase change process.
文摘An analysis is performed to study the influence of local thermal nonequilibrium(LTNE)on unsteadyMHDlaminar boundary layer flowof viscous,incompressible fluid over a vertical stretching plate embedded in a sparsely packed porous medium in the presence of heat generation/absorption.The flow in the porous medium is governed by Brinkman-Forchheimer extended Darcy model.A uniform heat source or sink is presented in the solid phase.By applying similarity analysis,the governing partial differential equations are transformed into a set of time dependent non-linear coupled ordinary differential equations and they are solved numerically by Runge-Kutta Fehlberg method along with shooting technique.The obtained results are displayed graphically to illustrate the influence of different physical parameters on the velocity,temperature profile and heat transfer rate for both fluid and solid phases.Moreover,the numerical results obtained in this study are compared with the existing literature in the case of LTE and found that they are in good agreement.
基金This research is supported by the National Natural Science Foundation of China-Deutsche Forschungsgemeinschaft Mobility Programme(M-0368).
文摘Aiming to efficiently simulate the transient process of transpiration cooling with phase change and reveal the convection mechanism between fluid and porous media particles in a continuum scale,a new two-phase mixture model is developed by incor-porating the local thermal non-equilibrium effect.Considering the low-pressure and high overload working conditions of hypersonic flying,the heat and mass transfer induced by capillary and inertial body forces are analyzed for sub-cooled,saturated and super-heated states of water coolant under varying saturation pressures.After the validation of the model,transient simulations for different external factors,includ-ing spatially-varied heat flux,coolant mass flux,time-dependent external pressure and aircraft acceleration are conducted.The results show that the vapor blockage patterns at the outlet are highly dependent on the injection mass flux value and the external pressure,and the reduced saturation temperature at low external pressure leads to early boiling off and vapor blockage.The motion of flying has a large influence on the cooling effect,as the inertial force could change the flow pattern of the fluid inside significantly.The comparison of the results from 2-D and 3-D simulations sug-gests that 3-D simulation shall be conducted for practical application of transpiration cooling,as the thermal protection efficiency may be overestimated by the 2-D results due to the assumption of an infinite width length of the porous plate.
