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  • Constrained Hamilton variational principle for shallow water problems and Zu-class symplectic algorithm 免费阅读 下载全文
  • In this paper, the shallow water problem is discussed. By treating the incompressible condition as the constraint, a constrained Hamilton variational principle is presented for the shallow water problem. Based on the constrained Hamilton variational principle, a shallow water equation based on displacement and pressure(SWE-DP)is developed. A hybrid numerical method combining the finite element method for spatial discretization and the Zu-class method for time integration is created for the SWEDP. The correctness of the proposed SWE-DP is verified by numerical comparisons with two existing shallow water equations(SWEs). The effectiveness of the hybrid numerical method proposed for the SWE-DP is also verified by numerical experiments. Moreover,the numerical experiments demonstrate that the Zu-class method shows excellent performance with respect to simulating the long time evolution of the shallow water.
  • Fluid-structure interaction simulation of three-dimensional flexible hydrofoil in water tunnel 免费阅读 下载全文
  • The closely coupled approach combined with the finite volume method(FVM) solver and the finite element method(FEM) solver is used to investigate the fluid-structure interaction(FSI) of a three-dimensional cantilevered hydrofoil in the water tunnel. The FVM solver and the coupled approach are verified and validated by comparing the numerical predictions with the experimental measurements, and good agreement is obtained concerning both the lift on the foil and the tip displacement. In the noncavitating flow, the result indicates that the growth of the initial incidence angle and the Reynolds number improves the deformation of the foil, and the lift on the foil is increased by the twist deformation. The normalized twist angle and displacement along the span of the hydrofoil for different incidence angles and Reynolds numbers are almost uniform. For the cavitation flow, it is shown that the small amplitude vibration of the foil has limited influence on the developing process of the partial cavity, and the quasi two-dimensional cavity shedding does not change the deformation mode of the hydrofoil. However, the frequency spectrum of the lift on the foil contains the frequency which is associated with the first bend frequency of the hydrofoil.
  • Stability analysis method considering non-parallelism: EPSE method and its application 免费阅读 下载全文
  • The e-N method is widely used in transition prediction. The amplitude growth rate used in the e-N method is usually provided by the linear stability theory(LST) based on the local parallel hypothesis. Considering the non-parallelism effect, the parabolized stability equation(PSE) method lacks local characteristic of stability analysis.In this paper, a local stability analysis method considering non-parallelism is proposed,termed as EPSE since it may be considered as an expansion of the PSE method. The EPSE considers variation of the shape function in the streamwise direction. Its local characteristic is convenient for stability analysis. This paper uses the EPSE in a strong non-parallel flow and mode exchange problem. The results agree well with the PSE and the direct numerical simulation(DNS). In addition, it is found that the growth rate is related to the normalized method in the non-parallel flow. Different results can be obtained using different normalized methods. Therefore, the normalized method must be consistent.
  • Fully developed forced convection through semi-elliptic ducts 免费阅读 下载全文
  • Numerical investigation of viscous fingering in Hele-Shaw cell with spatially periodic variation of depth 免费阅读 下载全文
  • Viscous fingering in a modified Hele-Shaw cell is numerically investigated.The cell allows periodic variation of depth in the lateral direction. The wavenumber n of the depth perturbation has great influence on fingering patterns. For n = 1, the fingering pattern due to the interface instability remains the same as that in the conventional Hele-Shaw cell, while the depth variation causes the steady finger to be a little narrower. For n = 2, four different fingering patterns are captured, similar to the available experimental observations in a modified Hele-Shaw cell containing a centered step-like occlusion. It is found that new fingering patterns appear as n further increases, among which, two patterns with spatial oscillation along both edges of the finger are particularly interesting.One is a symmetric oscillatory finger for n = 3, and the other is an asymmetric one for n = 4. The influence of capillary number on fingering patterns is studied for n = 3 and 4.We find that spatial oscillation of the finger nearly ceases at moderate capillary numbers and occurs again as the capillary number increases further. Meanwhile, the wide finger shifts to the narrow one. It is accompanied by a sudden decrease in the finger width which otherwise decreases continuously as the capillary number increases. The wavenumber and the amplitude of depth perturbation have little effect on the finger width.
  • Finite depth Stokes' first problem of thixotropic fluid 免费阅读 下载全文
  • This paper presents a study of the finite depth Stokes’ first problem for a thixotropic layer. The yield behavior of the thixotropic fluid in this problem is investigated for the first time. The main physical features of this problem are discussed, including the flow field, the wall stress, and the depth of the yield region. It is shown that the yield region appears near the wall, and the yield surface moves from the wall into the flow region and moves back to the wall finally. In contrast to the solution of the Newtonian fluid,the velocity of the thixotropic layer generally does not increase with time monotonously during the start-up process. The classical solution of the Newtonian fluid can be recovered from our results in extreme cases.
  • Numerical investigation of transonic flow over deformable airfoil with plunging motion 免费阅读 下载全文
  • Compressible closure models for turbulent multifluid mixing 免费阅读 下载全文
  • Aeroelastic dynamics stability of rotating sandwich annular plate with viscoelastic core layer 免费阅读 下载全文
  • A dynamic model for a rotating sandwich annular plate with a viscoelastic core layer is developed. All fundamental equations and boundary conditions are established based on Hamilton’s principle, and the rotation effect and viscoelastic properties of the sandwich structure are taken into account. The aerodynamics force acting on the plate is described by a rotating damping model, and the constitutive behavior of the viscoelastic core layer is formulated by the frequency-dependent complex modulus. The effects of geometrical and material parameters on frequencies and damping of forward and backward traveling waves and the dynamic stability for the rotating sandwich plate are numerically analyzed by means of Galerkin’s method. The results show that the critical and flutter speeds of the rotating plate can be increased at some certain parameters of the viscoelastic core layer.
  • Decoupling coefficients of dilatational wave for Biot's dynamic equation and its Green's functions in frequency domain 免费阅读 下载全文
  • Green’s functions for Biot’s dynamic equation in the frequency domain can be a highly useful tool for the investigation of dynamic responses of a saturated porous medium. Its applications are found in soil dynamics, seismology, earthquake engineering,rock mechanics, geophysics, and acoustics. However, the mathematical work for deriving it can be daunting. Green’s functions have been presented utilizing an analogy between the dynamic thermoelasticity and the dynamic poroelasticity in the frequency domain using the u-p formulation. In this work, a special term 'decoupling coefficient' for the decomposition of the fast and slow dilatational waves is proposed and expressed to present a new methodology for deriving the poroelastodynamic Green’s functions. The correctness of the solution is demonstrated by numerically comparing the current solution with Cheng’s previous solution. The separation of the two waves in the present methodology allows the more accurate evaluation of Green’s functions, particularly the solution of the slow dilatational wave. This can be advantageous for the numerical implementation of the boundary element method(BEM) and other applications.更多还原
  • INSTRUCTIONS FOR AUTHORS 免费阅读 下载全文
  • 《应用数学和力学:英文版》封面

    主管单位:交通部

    主办单位:上海大学

    社  长:秦钠

    主  编:周哲玮

    地  址:上海市宝山区上大路99号上海大学122信箱

    邮政编码:200444

    电  话:021-66135601 66135219

    电子邮件:[email protected]

    国际标准刊号:issn 0253-4827

    国内统一刊号:cn 31-1650/o1

    单  价:15.00

    定  价:180.00


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