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Mixed convective flow of a hybrid nanofluid between two parallel inclined plates under wall-slip condition

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Applied Mathematics and Mechanics(English Edition) 2022年第1期43卷 113-126页

作者： hang xu State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

The mixed convection flow of a hybrid nanofluid in an inclined channel with top wall-slip due to wall stripe and constant heat flux conditions is *** analytical solutions are given to the flow velocity,temperature,as well as the pressure in non-dimensional *** flow regime domain,the velocity and temperature distributions,and the dependence of various physical parameters such as the hybrid nanoparticle volume fractions,the wall-slip,the Grashof number,the Reynolds number,and the inclined angle are analyzed and *** is found that the hybrid nanofluid delays the appearance of flow reversal on both walls and the wall-slip postpones the flow reversal on the top wall.

关键词： inclined channel wall-slip hybrid nanofluid mixed convection

A modified model for isothermal homogeneous and heterogeneous reactions in the boundary-layer flow of a nanofluid

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Applied Mathematics and Mechanics(English Edition) 2020年第3期41卷 479-490页

作者： Naili xu hang xu State Key Laboratory of Ocean Engineering Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration(CISSE)School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The homogeneous and heterogeneous reactions in the boundary-layer of a flat surface are considered. The autocatalysts are assumed to be of regular sizes, while the solution is a dilute nanofluid. The heat release due to the chemical reactions is taken into account. The Buongiorno’s model is used to describe the behaviors of this reaction system. This configuration makes the current model be different from all previous publications. Multiple solutions are given numerically to the rescaled nonlinear system, whose stability is verified. The results show that the strength coefficients of the homogeneous and heterogeneous reactions are key factors to cause the appearance of the multiple solutions in the distribution of the chemical reactions. Nanofluids enhance the diffusion of heat and help maintain the stability of chemical reactions.

关键词： nanofluid homogeneous and heterogeneous reactions Buongiorno’s model multiple solutions stability analysis

Novel wavelet-homotopy Galerkin technique for analysis of lid-driven cavity flow and heat transfer with non-uniform boundary conditions

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Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1691-1718页

作者： Qiang YU hang xu Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE) State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University

In this paper, a brand-new wavelet-homotopy Galerkin technique is developed to solve nonlinear ordinary or partial differential equations. Before this investigation,few studies have been done for handling nonlinear problems with non-uniform boundary conditions by means of the wavelet Galerkin technique, especially in the field of fluid mechanics and heat transfer. The lid-driven cavity flow and heat transfer are illustrated as a typical example to verify the validity and correctness of this proposed technique. The cavity is subject to the upper and lower walls’ motions in the same or opposite *** inclined angle of the square cavity is from 0 to π/2. Four different modes including uniform, linear, exponential, and sinusoidal heating are considered on the top and bottom walls, respectively, while the left and right walls are thermally isolated and stationary.A parametric analysis of heating distribution between upper and lower walls including the amplitude ratio from 0 to 1 and the phase deviation from 0 to 2π is conducted. The governing equations are non-dimensionalized in terms of the stream function-vorticity formulation and the temperature distribution function and then solved analytically subject to various boundary conditions. Comparisons with previous publications are given,showing high efficiency and great feasibility of the proposed technique.

关键词： wavelet-homotopy Galerkin technique mixed boundary condition liddriven inclined cavity non-uniform heat transfer

Nonlinear dynamical magnetosonic wave interactions and collisions in magnetized plasma

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Applied Mathematics and Mechanics(English Edition) 2020年第8期41卷 1139-1156页

作者： M.ISHAQ hang xu State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The one-dimensional nonlinear dynamical wave interactions in a system of quasineutral two-fluid plasma in a constant magnetic field are *** existence of the travelling wave solutions is *** modulation stability of linear waves and the modulation instability of weakly nonlinear waves are *** suggest that the Korteweg-de Vries(KdV)system is modulationally ***,the wave interactions including the periodic wave interaction and the solitary wave interaction are captured and *** is shown that these interacting waves alternately exchange their energy during *** Fourier spectrum analysis is used to depict the energy transformation between the primary and harmonic *** is known that the wave interactions in magnetized plasma play an important role in various processes of heating and energy transportation in space and astrophysical ***,few researchers have considered such magnetohydrodynamic(MHD)wave interactions in *** is expected that this work can provide additional insight into understanding of behaviors of MHD wave interactions.

关键词： magnetosonic wave periodic wave solitary wave modulation instability Fourier spectrum dispersion relation

Water diversion and agricultural production:Evidence from China

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Journal of Integrative Agriculture 2023年第4期22卷 1244-1257页

作者： YANG Rui xu hang College of Humanities and Development Studies China Agricultural UniversityBeijing 100193P.R.China College of Economics and Management Northwest A&F UniversityYangling 712100P.R.China

Water diversion can alleviate water shortages caused by the uneven distribution of water ***’s Southto-North Water Diversion Project(SNWD)is the largest water diversion project *** on the prefecturelevel data of China’s Huang-Huai-Hai Plain from 2000 to 2020,this study employs an empirical strategy of Differencesin-Differences(DID)to analyze the impact of SNWD on agricultural *** results show that SNWD has significantly increased agricultural production,measured by the agricultural value *** estimated results of the benchmark model remain robust when the contemporaneous policy is addressed,an alternative outcome is used,subsamples are estimated,and alternative estimation techniques are *** study argues that the potential impact mechanism may be that SNWD significantly increases the acreage for cash crops but reduces that for grain *** analysis shows that in prefectures with high temperature or land potential,SNWD’s impact on agricultural value added is relatively *** contrast,in areas with prolonged sunshine or high slopes,SNWD’s impact on agricultural value added is relatively *** the low added value of grain crops,the government should consider strengthening food security by subsidizing water supply to sustain grain production.

关键词： South-to-North Water Diversion Project agricultural production Differences-in-Differences China

Homotopy Coiflets wavelet solution of electrohydrodynamic flows in a circular cylindrical conduit

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Applied Mathematics and Mechanics(English Edition) 2020年第5期41卷 681-698页

作者： Anyang WANG hang xu Qiang YU State Key Lab of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 201306China

In previous studies, the nonlinear problem of electrohydrodynamic(EHD)ion drag flows in a circular cylindrical conduit has been studied by several authors. However, those studies seldom involve the computation for large physical parameters such as the electrical Hartmann number and the magnitude parameter for the strength of the nonlinearity due to the existence of strong nonlinearity in these extreme cases. To overcome this faultiness, the newly-developed homotopy Coiflets wavelet method is extended to solve this EHD flow problem with strong nonlinearity. The validity and reliability of the proposed technique are verified. Particularly, the highly accurate homotopy-wavelet solution is obtained for extreme large parameters, which seems to be overlooked *** about the effects of related physical parameters on the axial velocity field is presented.

关键词： homotopy-wavelet method Coiflets electrohydrodynamic(EHD)flow nonlinear boundary value problem(BVP)

Analysis of periodic pulsating nanofluid flow and heat transfer through a parallel-plate channel in the presence of magnetic field

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Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1957-1972页

作者： Qingkai ZHAO Longbin TAO hang xu School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100Jiangsu ProvinceChina Department of Naval Architecture Ocean and Marine EngineeringUniversity of StrathclydeGlasgow G4 OLZU.K. State Key Lab of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

In this paper,we focus on the two-dimensional pulsating nanofluid flow through a parallel-plate channel in the presence of a magnetic *** pulsating flow is produced by an applied pressure gradient that fluctuates with a small amplitude.A kind of proper transformation is used so that the governing equations describing the momentum and thermal energy are reduced to a set of non-dimensional *** analytical expressions of the pulsating velocity,temperature,and Nusselt number of nanofluids are obtained by the perturbation *** the present study,the effects of the Cu-H2O and Al_(2)O_(3)-H2O nanofluids on the flow and heat transfer in pulsating flow are compared and *** results show that the convective heat transfer effect of Cu-H2O nanofluids is better than that of Al_(2)O_(3)-H2O ***,the effects of the Hartmann number and pulsation amplitude on the velocity,temperature,and Nusselt number are examined and discussed in *** present work indicates that increasing the Hartmann number and pulsation amplitude can enhance the heat transfer of the pulsating *** addition,selecting an optimal pulsation frequency can maximize the convective heat transfer of the pulsating ***,improved understanding of these fundamental mechanisms is conducive to the optimal design of thermal systems.

关键词： nanofluid pulsating flow heat transfer applied magnetic field

The jet over a stretching wall with suction or injection

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Science China(Physics,Mechanics & Astronomy) 2011年第3期54卷 502-510页

作者： xu hang WU GuoXiong State Key Laboratory of Ocean Engineering School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Mechanical Engineering University College London London WC1E7JE UK

The steady laminar wall jet over a stretching surface in the presence of lateral suction or injection is considered. Similarity solutions absent in previous publications are found in some new ranges of parameters in the governing equation. The accuracy and reliability of the solutions have been checked through detailed convergence study and compared with the solutions from the numerical method and analytic method, and excellent agreement has been found. This gives the strongest evidence that those solutions are indeed new ones.

关键词： wall jet stretching wall injection/suction similarity solution

ACCELERATION METHODS OF NONLINEAR ITERATION FOR NONLINEAR PARABOLIC EQUATIONS

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Journal of Computational Mathematics 2006年第3期24卷 412-424页

作者： Guang-wei Yuan xu-deng hang Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O.Box 8009 Beijing 100088 China

This paper discusses the accelerating of nonlinear parabolic equations. Two iterative methods for solving the implicit scheme new nonlinear iterative methods named by the implicit-explicit quasi-Newton （IEQN） method and the derivative free implicit-explicit quasi-Newton （DFIEQN） method are introduced, in which the resulting linear equations from the linearization can preserve the parabolic characteristics of the original partial differential equations. It is proved that the iterative sequence of the iteration method can converge to the solution of the implicit scheme quadratically. Moreover, compared with the Jacobian Free Newton-Krylov （JFNK） method, the DFIEQN method has some advantages, e.g., its implementation is easy, and it gives a linear algebraic system with an explicit coefficient matrix, so that the linear （inner） iteration is not restricted to the Krylov method. Computational results by the IEQN, DFIEQN, JFNK and Picard iteration methods are presented in confirmation of the theory and comparison of the performance of these methods.

关键词： Nonlinear parabolic equations Difference scheme Newton iterative methods.