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31.
A cost‐effective curvature calculation approach for interfacial flows on unstructured meshes 下载免费PDF全文
We present a simple and cost‐effective curvature calculation approach for simulations of interfacial flows on structured and unstructured grids. The interface is defined using volume fractions, and the interface curvature is obtained as a function of the gradients of volume fractions. The gradient computation is based on a recently proposed gradient recovery method that mimicks the least squares approach without the need to solve a system of equations and is quite easy to implement on arbitrary polygonal meshes. The resulting interface curvature is used in a continuum surface force formulation within the framework of a well‐balanced finite‐volume algorithm to simulate multiphase flows dominated by surface tension. We show that the proposed curvature calculation is at least as accurate as some of the existing approaches on unstructured meshes while being straightforward to implement on any mesh topology. Numerical investigations also show that spurious currents in stationary problems that are dependent on the curvature calculation methodology are also acceptably low using the proposed approach. Studies on capillary waves and rising bubbles in viscous flows lend credence to the ability of the proposed method as an inexpensive, robust, and reasonably accurate approach for curvature calculation and numerical simulation of multiphase flows. 相似文献
32.
The electric field gradients at27Al and63Cu nuclei which are nearest neighbors to the muon in the face-centered cubic metals aluminum and copper, with muon at an octahedral
interstitial site, are studied. The electron density fluctuations needed for the evaluation of the electronic, or valence,
contributions to field gradients are taken from earlier investigations involving the spherical solid approximation. The enhancement
factors a that have to be applied to the electric field-gradients obtained from these approximations, due to the departures
of the electronic wave-functions from plane-wave character, and the incorporation of antishielding effects, have been obtained
for both APW and OPW approaches to the conduction electron wave-functions and good agreement is found between the results
by the two approaches. Size effects due to the lattice distortion associated with the presence of the muon are included through
actual point ion summations using available calculated displacements of the ions surrounding the muon. The valence contributions
are the dominant ones but the size effect contributions are also significant. The net field-gradient obtained for the27Al site is significantly smaller than experiment while that for63Cu is substantially larger than experiment. Possible sources that could lead to better agreement with experiment are discussed
and it is concluded that major improvement is needed in the valence effect contributions in both metals. 相似文献
33.
Gamma-induced modifications in polycarbonate polymer have been studied in the dose range of 101–106 Gy. Thin films of polycarbonate have been irradiated with different gamma doses from a Co60 source. To monitor the modifications caused by gamma radiation, FT-IR, differential scanning calorimetry and X-ray diffraction studies have been performed. The studies have indicated that at the dose of 106 Gy, phenolic group forms through scissioning of ester linkage. Though the effect of radiation is most significant at the highest dose, the process of modifications starts at 103 Gy. Scissioning of the polymeric chain initiates a different morphological zone within the polymer matrix, and the polymer becomes more crystalline with increasing dose. Owing to chain scissioning, the mobility of the polymer increases, which in turn reduces the glass transition temperature of the polymer. 相似文献
34.
For distinct points x1,x2,…,xn in ℛ (the reals), letϕ[x1, x2,…,xn] denote the divided difference ofϕ. In this paper, we determine the general solutionϕ,g: ℛ → ℛ of the functional equationϕ[x1,x2,…,xn] =g(x1,+ x2 + … + xn) for distinct x1,x2,…, xn in ℛ without any regularity assumptions on the unknown functions. 相似文献
35.
Jitendra Pal Singh Gagan Dixit R.C. Srivastava H.M. Agrawal V.R. Reddy Ajay Gupta 《Journal of magnetism and magnetic materials》2012
We investigated the magnetic behavior of nanosized zinc ferrite with the help of vibrating sample magnetometry and in-field Mössbauer spectroscopy. The nanoparticles of zinc ferrite with crystallite size ranging from 10 to 62 nm were synthesized by a nitrate method. The structure and phase were determined with the help of X-ray diffraction. Attributes of cation inversion were found with the calculated values of lattice parameter. The saturation magnetization decreases with the increase in crystallite size at room temperature, while these values are almost the same at 10 K for all the samples except the one with crystallite size of 10 nm. The thermal magnetization measurement shows a decrease in blocking temperature with increase in particle size for these samples. The synthesized samples exhibit the presence of antiferromagnetic ordering below the blocking temperature as investigated by in-field Mössbauer spectroscopy. 相似文献
36.
Satyabrata Sahoo Y.K. Ho 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(1):52-62
We present theoretical photoionization cross sections for He 1s2s 1S and He 1s2p 1P states in a Debye plasma environment by the complex coordinate rotation method, using a finite L2 basis set constructed from one electron Laguerre orbitals. The plasma environment is found to appreciably influence the photoionization cross sections near the ionization threshold. In this regard, the photoionization cross sections of isolated He are compared with other theoretical and experimental results. Our results are in good agreement with the previous results. A new minimum appears in the photoionization cross section curve for the metastable 1s2s 1S state. Results are given for the S- and D-wave partial photoionization for the excited 1s2p 1P state. 相似文献
37.
Bikash Sahoo 《Communications in Nonlinear Science & Numerical Simulation》2009,14(7):2982-2998
The steady Von Kármán flow and heat transfer of an electrically conducting non-Newtonian fluid is extended to the case where the disk surface admits partial slip. The fluid is subjected to an external uniform magnetic field perpendicular to the plane of the disk. The constitutive equation of the non-Newtonian fluid is modeled by that for a Reiner–Rivlin fluid. The momentum equations give rise to highly non-linear boundary value problem. Numerical solutions for the governing non-linear equations are obtained over the entire range of the physical parameters. The effects of slip, magnetic parameter and non-Newtonian fluid characteristics on the velocity and temperature fields are discussed in detail and shown graphically. Emphasis has been laid to study the effects of viscous dissipation and Joule heating on the thermal boundary layer. It is interesting to find that the non-Newtonian cross-viscous parameter has an opposite effect to that of the slip and the magnetic parameter on the velocity and the temperature fields. 相似文献
38.
A new method for exact solutions of variant types of time‐fractional Korteweg‐de Vries equations in shallow water waves 下载免费PDF全文
The current article devoted on the new method for finding the exact solutions of some time‐fractional Korteweg–de Vries (KdV) type equations appearing in shallow water waves. We employ the new method here for time‐fractional equations viz. time‐fractional KdV‐Burgers and KdV‐mKdV equations for finding the exact solutions. We use here the fractional complex transform accompanied by properties of local fractional calculus for reduction of fractional partial differential equations to ordinary differential equations. The obtained results are demonstrated by graphs for the new solutions. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
39.
Effect of Temperature and Discharge Rate on Electrochemical Performance of Fiber Nickel–Cadmium Cell
Senthilkumar M. Satyavani T. V. S. L. Raman M. Venkat Sahoo P. K. Kumar A. Srinivas 《Russian Journal of Electrochemistry》2022,58(1):43-49
Russian Journal of Electrochemistry - The effect of temperature and discharge rate on the discharge capacity of nickel–cadmium (Ni?Cd) cell is investigated quantitatively. Ni–Cd... 相似文献
40.
The optical response time of a nematic liquid crystal (NLC) decreases due to incorporation of carbon nanotubes (CNTs) in the liquid-crystal host. Such reduction is believed to be due to an increase in the elastic constant of the nanotube-doped LC system. In this paper, we present the effect on optical response due to doping an NLC with octadecylamine functionalised single-walled carbon nanotubes (ODA-SWCNT) in a twisted alignment mode. The electro-optic switching amplitude of ODA-SWCNT nanocomposites of NLC decreases compared to pure NLC. A fast response time is observed with an increase in the concentration of ODA-SWCNT in NLC host. Additionally, optical response of pure NLC in a twisted nematic (TN) cell fabricated using mixtures of polyimide (PI) and ODA-SWCNT as an alignment layer is investigated. The optical response time decreased by ~75% in a TN cell fabricated with a mixture of PI and ODA-SWCNT compared to that of a TN cell prepared using a pure PI alignment layer. The presence of ODA-SWCNT in the alignment layer enhances the surface anchoring of the NLC molecules leading to an increase in the elastic constant and a decrease in the optical response time of NLC. 相似文献