Hybrid nanofluids have gained significant attention for their superior thermal and rheological characteristics,offering immense potential in energy conversion,biomedical transport,and electromagnetic flow control syst...Hybrid nanofluids have gained significant attention for their superior thermal and rheological characteristics,offering immense potential in energy conversion,biomedical transport,and electromagnetic flow control systems.Understanding their dynamic behavior under coupled magnetic,rotational,and reactive effects is crucial for the development of efficient thermal management technologies.This study develops a neuro-fuzzy computational framework to examine the dynamics of a reactive Cu–TiO_(2)–H_(2)Ohybrid nanofluid flowing through a squarely elevated Riga tunnel.The governing model incorporates Hall and ion-slip effects,thermal radiation,and first-order chemical reactions under ramped thermo-solutal boundary conditions and rotational electromagnetic forces.Closed-form analytical solutions are derived via the Laplace transform method to describe the transient velocity,temperature,and concentration fields.To complement and validate the analytical model,an artificial neural network(ANN)optimized using the Levenberg–Marquardt backpropagation algorithm(ANN-LMBPA)is trained on datasets generated in Mathematica.Regression and error analyses confirm the model’s predictive robustness,with mean squared errors ranging between 10^(-4) and 10^(-9).In addition,an Adaptive Neuro-Fuzzy Inference System(ANFIS)is developed to estimate the heat transfer rate(HTR),achieving aminimal RMSE of 0.011012 for the heat transfer coefficient(HTC).The findings reveal that rotational motion and Hall–ion slip effects suppress primary velocity but enhance secondary flow,while the modified Hartmann number(Lorentz force)accelerates both components.Thermal radiation increases fluid temperature,whereas higher Schmidt numbers and reaction rates diminish solute concentration.The HTR decreases with increasing radiation and nanoparticle volume fraction,while the mass transfer rate(MTR)improves under stronger chemical reactivity.Overall,the proposed hybrid analytical–AI framework demonstrates high accuracy and efficiency,offering valuable insights for the design and optimization of electromagnetic nanofluid systems in advanced thermal and process engineering applications.展开更多
As a necessary step toward the quantitative predictions of macro-segregation commonly found in metal castings, classical experiments and numerical benchmarks have been used to validate a simplified binary- alloy solid...As a necessary step toward the quantitative predictions of macro-segregation commonly found in metal castings, classical experiments and numerical benchmarks have been used to validate a simplified binary- alloy solidification model. The model consists of fully coupled conservation equations for the transport phenomena （heat transfer, solute redistribution, ~tnd melt convection） that lead to macro-segregation in a solidifying ingot with a fixed solid phase. Simulations were performed for solidification of either a Pb-48wt.%Sn or a Sn-5wt.%Pb alloy in a rectangular cavity. The present predictions were compared with experimental data and numerical reference results reported in the literature. Subsequently, the model was applied to a numerical benchmark problem described in the literature for solidification of a Sn-10wt.%Pb alloy. Simulation results for flow velocity, liquid fraction evolution, and macro-segregation maps also were compared with literature predictions, showing similar trends. It is concluded that additional comparisons to experimental results are still required to assess more complex solidification models.展开更多
The aim of this paper is to numerically investigate the influence of nanoparticles shape on heat and mass transport phenomena in a moving lid cavity under the combined effect of thermo-solutal buoyancy force and magne...The aim of this paper is to numerically investigate the influence of nanoparticles shape on heat and mass transport phenomena in a moving lid cavity under the combined effect of thermo-solutal buoyancy force and magnetic force.The governing equations are transformed into velocity-vorticity form of equations and solved using Galerkin's weighted residual finite-element-technique.The analysis has been carried out with parameters like buoyancy ratio(−5≤N≤5),magnetic field inclination angle(0°≤ϕ≤90°)with four shapes of Al_(2)O_(3) nanoparticle like bricks,blades,platelets and cylinders.The results revealed that the shape factor on Nusselt number is significant depending upon the inclined magnetic field and buoyancy ratio whereas on mass transfer the shape effect is negligible.The diffusion mode of transport process is stronger than the convection mode at higher inclination angle of magnetic field.Based on a given value of N andϕ,blade and cylinder shows the best performance in Nusselt and Sherwood number respectively except the platelet shape that shows maximum frictional loss in terms of wall shear stress.展开更多
The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdraw...The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdrawal rate is a critical parameter affecting the spatial distribution ofγ/γ′eutectic along gravity direction.The results show that theγ/γ′eutectic fraction of the upper platform surface is always higher than that of the lower one,regardless of withdrawal rate.As the withdrawal rate decreases,there is a significant increase inγ/γ′eutectic fraction on the upper surface,while it decreases on the lower surface.The upward accumulation ofγ/γ′eutectic becomes more severe as the withdrawal rate decreases.It is also found that the percentage of Al+Ta is positively correlated with theγ/γ′eutectic fraction.Thermo-solute convection of Al and Ta solutes in the solidification front is the prime reason for the non-uniform distribution of eutectic.The non-uniform distribution ofγ/γ′eutectic cannot be eliminated even after subsequent solution heat treatment,resulting in excess eutectic on the upper surface and thus leading to the scrapping of the blade.展开更多
A mathematical model coupling the momentum, energy and species conservation equa-tions was proposed to calculate the macro--segregation of Fe--C alloy ingot during solid-ification. The corresponding simulation softwar...A mathematical model coupling the momentum, energy and species conservation equa-tions was proposed to calculate the macro--segregation of Fe--C alloy ingot during solid-ification. The corresponding simulation software which concurrently solves the macro-scopic mass, momentum, energy and species conservation equations has been developedby applying the SIMPLE algorithm.The thermo--solutal convection in a NH_4 Cl--H_2O ingot is verified and the result showsgood agreement with that reported. Then macro--segregation in a steel ingot is simu-lated by using the developed program. The steel ingot is in a rectangular mold with ariser. The fluid flow is mainly induced by the temperature field and the solid fraction.The macro--segregation pattern is mainly affected by the thermo--induced convectionin the mushy zone. The negative segregation forms along the walls of the casting.The positive segregation forms at the top center of the casting into the riser. Thespecies concentration reaches the peak in the center of the ingot where solidificationends lastly.展开更多
文摘Hybrid nanofluids have gained significant attention for their superior thermal and rheological characteristics,offering immense potential in energy conversion,biomedical transport,and electromagnetic flow control systems.Understanding their dynamic behavior under coupled magnetic,rotational,and reactive effects is crucial for the development of efficient thermal management technologies.This study develops a neuro-fuzzy computational framework to examine the dynamics of a reactive Cu–TiO_(2)–H_(2)Ohybrid nanofluid flowing through a squarely elevated Riga tunnel.The governing model incorporates Hall and ion-slip effects,thermal radiation,and first-order chemical reactions under ramped thermo-solutal boundary conditions and rotational electromagnetic forces.Closed-form analytical solutions are derived via the Laplace transform method to describe the transient velocity,temperature,and concentration fields.To complement and validate the analytical model,an artificial neural network(ANN)optimized using the Levenberg–Marquardt backpropagation algorithm(ANN-LMBPA)is trained on datasets generated in Mathematica.Regression and error analyses confirm the model’s predictive robustness,with mean squared errors ranging between 10^(-4) and 10^(-9).In addition,an Adaptive Neuro-Fuzzy Inference System(ANFIS)is developed to estimate the heat transfer rate(HTR),achieving aminimal RMSE of 0.011012 for the heat transfer coefficient(HTC).The findings reveal that rotational motion and Hall–ion slip effects suppress primary velocity but enhance secondary flow,while the modified Hartmann number(Lorentz force)accelerates both components.Thermal radiation increases fluid temperature,whereas higher Schmidt numbers and reaction rates diminish solute concentration.The HTR decreases with increasing radiation and nanoparticle volume fraction,while the mass transfer rate(MTR)improves under stronger chemical reactivity.Overall,the proposed hybrid analytical–AI framework demonstrates high accuracy and efficiency,offering valuable insights for the design and optimization of electromagnetic nanofluid systems in advanced thermal and process engineering applications.
基金supported by the National Science and Technology Major Project of China(No.2011ZX04014-052)the National Basic Research Program of China(No.2011CB012900)
文摘As a necessary step toward the quantitative predictions of macro-segregation commonly found in metal castings, classical experiments and numerical benchmarks have been used to validate a simplified binary- alloy solidification model. The model consists of fully coupled conservation equations for the transport phenomena （heat transfer, solute redistribution, ~tnd melt convection） that lead to macro-segregation in a solidifying ingot with a fixed solid phase. Simulations were performed for solidification of either a Pb-48wt.%Sn or a Sn-5wt.%Pb alloy in a rectangular cavity. The present predictions were compared with experimental data and numerical reference results reported in the literature. Subsequently, the model was applied to a numerical benchmark problem described in the literature for solidification of a Sn-10wt.%Pb alloy. Simulation results for flow velocity, liquid fraction evolution, and macro-segregation maps also were compared with literature predictions, showing similar trends. It is concluded that additional comparisons to experimental results are still required to assess more complex solidification models.
文摘The aim of this paper is to numerically investigate the influence of nanoparticles shape on heat and mass transport phenomena in a moving lid cavity under the combined effect of thermo-solutal buoyancy force and magnetic force.The governing equations are transformed into velocity-vorticity form of equations and solved using Galerkin's weighted residual finite-element-technique.The analysis has been carried out with parameters like buoyancy ratio(−5≤N≤5),magnetic field inclination angle(0°≤ϕ≤90°)with four shapes of Al_(2)O_(3) nanoparticle like bricks,blades,platelets and cylinders.The results revealed that the shape factor on Nusselt number is significant depending upon the inclined magnetic field and buoyancy ratio whereas on mass transfer the shape effect is negligible.The diffusion mode of transport process is stronger than the convection mode at higher inclination angle of magnetic field.Based on a given value of N andϕ,blade and cylinder shows the best performance in Nusselt and Sherwood number respectively except the platelet shape that shows maximum frictional loss in terms of wall shear stress.
基金Shenzhen Science and Technology Program(JSGG20220831092800001)。
文摘The microstructure of single crystal superalloy is relatively simple,consisting primarily ofγdendrites andγ/γ′eutectics.During the directional solidification process of Ni-based single crystal superalloys,withdrawal rate is a critical parameter affecting the spatial distribution ofγ/γ′eutectic along gravity direction.The results show that theγ/γ′eutectic fraction of the upper platform surface is always higher than that of the lower one,regardless of withdrawal rate.As the withdrawal rate decreases,there is a significant increase inγ/γ′eutectic fraction on the upper surface,while it decreases on the lower surface.The upward accumulation ofγ/γ′eutectic becomes more severe as the withdrawal rate decreases.It is also found that the percentage of Al+Ta is positively correlated with theγ/γ′eutectic fraction.Thermo-solute convection of Al and Ta solutes in the solidification front is the prime reason for the non-uniform distribution of eutectic.The non-uniform distribution ofγ/γ′eutectic cannot be eliminated even after subsequent solution heat treatment,resulting in excess eutectic on the upper surface and thus leading to the scrapping of the blade.
基金This work was financially supported by the National NSFC BaoSteel Conjunct Foun dation(No.50174031).
文摘A mathematical model coupling the momentum, energy and species conservation equa-tions was proposed to calculate the macro--segregation of Fe--C alloy ingot during solid-ification. The corresponding simulation software which concurrently solves the macro-scopic mass, momentum, energy and species conservation equations has been developedby applying the SIMPLE algorithm.The thermo--solutal convection in a NH_4 Cl--H_2O ingot is verified and the result showsgood agreement with that reported. Then macro--segregation in a steel ingot is simu-lated by using the developed program. The steel ingot is in a rectangular mold with ariser. The fluid flow is mainly induced by the temperature field and the solid fraction.The macro--segregation pattern is mainly affected by the thermo--induced convectionin the mushy zone. The negative segregation forms along the walls of the casting.The positive segregation forms at the top center of the casting into the riser. Thespecies concentration reaches the peak in the center of the ingot where solidificationends lastly.
