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91.
92.
A numerical model based on the smoothed particle hydrodynamics method is developed to simulate depth‐limited turbulent open channel flows over hydraulically rough beds. The 2D Lagrangian form of the Navier–Stokes equations is solved, in which a drag‐based formulation is used based on an effective roughness zone near the bed to account for the roughness effect of bed spheres and an improved sub‐particle‐scale model is applied to account for the effect of turbulence. The sub‐particle‐scale model is constructed based on the mixing‐length assumption rather than the standard Smagorinsky approach to compute the eddy‐viscosity. A robust in/out‐flow boundary technique is also proposed to achieve stable uniform flow conditions at the inlet and outlet boundaries where the flow characteristics are unknown. The model is applied to simulate uniform open channel flows over a rough bed composed of regular spheres and validated by experimental velocity data. To investigate the influence of the bed roughness on different flow conditions, data from 12 experimental tests with different bed slopes and uniform water depths are simulated, and a good agreement has been observed between the model and experimental results of the streamwise velocity and turbulent shear stress. This shows that both the roughness effect and flow turbulence should be addressed in order to simulate the correct mechanisms of turbulent flow over a rough bed boundary and that the presented smoothed particle hydrodynamics model accomplishes this successfully. © 2016 The Authors International Journal for Numerical Methods in Fluids Published by John Wiley & Sons Ltd 相似文献
93.
Z. M. Lv H. Y. Wu J. L. Zhang M. Li Z. Wei H. O. Li X. F. Guo L. Z. Cao K. Q. Ruan 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(2):161-165
The magnetic superconductor RuSr2Gd1.4Ce0.6Cu2O10-
δ was studied by means of detailed magnetization measurements in order to clarify its complex magnetic and superconducting
properties. Our experiments agree with a model indicating that the in-plane component of the Ru moment might transform from
a spin-glass ground state to a ferromagnetically coupled excited state by application of a small magnetic field below the
magnetic transition temperature. The experiments also show that a full Meissner state is present at the low temperature, the
low magnetic field region of the phase diagram. This is in contrast to the previous prediction that no Meissner state exists
in this material for an internal magnetic field of several hundred Oersteds in the CuO2 planes exerted by the Ru sublattice and exceeding the lower critical field. 相似文献
94.
An analytical solution of self-similar waves, Hermite-Gaussian solitons, emerging in a strongly nonlocal thermal nonlinear medium with the rectangular boundaries was found. The theoretical analysis and numerical simulation showed that the Hermite-Gaussian solitons are elliptic and form a rectangular matrix cluster. Moreover, the symmetries of the soliton and matrix cluster depend not only on the boundary conditions, but also on the symmetry and power of the input beam as well as the propagation distance. The particular interest lies in that the intensities of the solitons in the edges of the rectangular cluster are bigger than those on the center, the most intense solitons occurring at four angles. 相似文献
95.
96.
Alessio Figalli 《Rendiconti del Circolo Matematico di Palermo》2009,58(2):283-286
In this work we study the global regularity of the free boundaries arising in the optimal partial transport problem. Assuming
the supports of both the source and the target measure to be convex, we show that the free boundaries of the active regions
are globally C
0,1/2.
相似文献
97.
Luciano Gonç alves Noleto Manuel N. D. Barcelos Jr. & Antonio C. P. Brasil Jr. 《advances in applied mathematics and mechanics.》2013,5(2):194-211
This work presents a moving mesh methodology based on the solution
of a pseudo flow problem. The mesh motion is modeled as a pseudo Stokes
problem solved by an explicit finite element projection method. The mesh
quality requirements are satisfied by employing a null divergent velocity
condition. This methodology is applied to triangular unstructured meshes
and compared to well known approaches such as the ones based on diffusion
and pseudo structural problems. One of the test cases is an airfoil with
a fully meshed domain. A specific rotation velocity is imposed as the
airfoil boundary condition. The other test is a set of two cylinders
that move toward each other. A mesh quality criterion is employed to
identify critically distorted elements and to evaluate the performance
of each mesh motion approach. The results obtained for each test case
show that the pseudo-flow methodology produces satisfactory meshes
during the moving process. 相似文献
98.
J. Kplé S. Massou F. Hontinfinde E. Albayrak 《Chinese Journal of Physics (Taipei)》2018,56(3):1252-1261
A bilayer spin-1/2 Ising model consisting of two superposed Bethe lattices with antiferromagnetic/ferromagnetic interactions is studied by the use of exact recursion relations in a pairwise approach in the presence of an external staggered magnetic field. Besides the ground state phase diagrams calculated in different possible planes of the model parameters space, the thermal variations of the order-parameters and the free energy are investigated to obtain the temperature-dependent phase diagrams of the model for different values of the coordination numbers q. Our calculations reveal that depending on the strength of the model parameters, the model exhibits a variety of interesting phase transitions and therefore phase diagrams. 相似文献
99.
《Current Applied Physics》2018,18(10):1149-1157
Different type doped CaBi2Nb2O9 (CBN) ceramics were prepared by a conventional solid state sintering method. The number of oxygen vacancies were decreased or increased by the introduction of W6+ and Ti4+ doping in CBN ceramics. The influence of W6+, Ti4+ and W6+/Ti4+ dopants on the microstructures and electrical properties of CBN-based ceramics was investigated. The voids and spherical morphology in the SEM image of W, Ti co-doped ceramics indicate that W, Ti co-doping could change the microstructure of CBN-based ceramics. Impedance analysis results show that the electrical properties of CBN-based ceramics have a close relationship with the number of oxygen vacancies. W doping and W, Ti co-doping decrease the oxygen vacancies, as a result, the resistance and piezoelectric properties were increased and the frequency dispersion of dielectric properties were restrained. 相似文献
100.
In this work, the effect of the material microstructural interface between two materials (i.e., grain boundary in polycrystalls) is adopted into a thermodynamic-based higher order strain gradient plasticity framework. The developed grain boundary flow rule accounts for the energy storage at the grain boundary due to the dislocation pile up as well as energy dissipation caused by the dislocation transfer through the grain boundary. The theory is developed based on the decomposition of the thermodynamic conjugate forces into energetic and dissipative counterparts which provides the constitutive equations to have both energetic and dissipative gradient length scales for the grain and grain boundary. The numerical solution for the proposed framework is also presented here within the finite element context. The material parameters of the gradient framework are also calibrated using an extensive set of micro-scale experimental measurements of thin metal films over a wide range of size and temperature of the samples. 相似文献