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991.
Unsteady model of drop Marangoni migration in microgravity 总被引:1,自引:0,他引:1
The experiments of drop Marangoni migration have been performed by the drop shift facility of short period of 4.5 s, and the
drop accelerates gradually to an asymptotic velocity during the free fall. The unsteady and axisymmetric model is developed
to study the drop migration for the case of moderate Reynolds numberRe=O(1), and the results are compared with the experimental ones in the present paper. Both numerical and experimental results
show that the migration velocity for moderate Reynolds number is several times smaller than that given by the linear YGB theory.
The project supported by the National Natural Science Foundation (19789201) and the Ministry of Science and Technology of
China (95-Yu-34) 相似文献
992.
陈松林 《应用数学和力学(英文版)》2002,23(5):618-618
ThefollowingLemmastated (in :AppliedMathematicsandMechanics (EnglishEdition) ,2 0 0 1 ,2 2 ( 1 1 ) :1 3 52 -1 3 56)wasappliedtodescribetheasymptoticbehaviorsofsolutionsofaclassofreaction_diffusionequation .Onaccountofthespecialpropertyofthesupersolution(i.e .,anonzerosolution… 相似文献
993.
A new model shift mapping was given in bilateral symbol space. It is topologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, a model was constructed correspondent to the model shift mapping, i.e., a class of mapping on Mbius strip was given. Its attractors’ structure and dynamical behaviour were described. 相似文献
994.
Magnetoconvective instabilities in a rapidly rotating, electrically conducting fluid layer heated from below in the presence
of a non-uniform, horizontal magnetic field are investigated. It was first shown by Chandrasekhar that an overall minimum
of the Rayleigh number may be reached at the onset of magnetoconvection when a uniform basic magnetic field is imposed. In
this paper, we show that the properties of instability can be quite different when a non-uniform basic magnetic field is applied.
It is shown that there is an optimum value of the Elsasser number provided that the basic magnetic field is a monotonically
decreasing or increasing function of the vertical coordinate. However, there exist no optimum values of the Elsasser number
that can give rise to an overall minimum of the Rayleigh number at the onset of magnetoconvection if the imposed basic magnetic
field has an inflexion point.
The project supported by the National Natural Science Foundation of China (40174026 and 40074041) 相似文献
995.
The method of boundary layer with multiple scales and computer algebra were applied to study the asymptotic behavior of solution
of boundary value problems for a class of system of nonlinear differential equations. The asymptotic expansions of solution
were constructed. The remainders were estimated. And an example was analysed. It provides a new foreground for the application
of the method of boundary layer with multiple scales.
Contributed by Jiang Fu-ru, Original Member of Editorial Committe, AMM
Biography: Xie La-bing (1976∼); Jiang Fu-ru(1927∼) 相似文献
996.
It is observed that the harmonic balance (HB) method of parametric identification of nonlinear system may not give right identification
results for a single test data. A multiple-trial HB scheme is suggested to obtain improved results in the identification,
compared with a single sample test. Several independent tests are conducted by subjecting the system to a range of harmonic
excitations. The individual data sets are combined to obtain the matrix for inversion. This leads to the mean square error
minimization of the entire set of periodic orbits. It is shown that the combination of independent test data gives correct
results even in the case where the individual data sets give wrong results. 相似文献
997.
A. S. Bansode Siddharth Patel T. Rajesh Kumar B. Muralidhar T. Sundararajan Sarit Kumar Das 《Heat and Mass Transfer》2007,43(10):1037-1047
A 3D numerical study was carried out to analyze flow, heat and mass transfer first in a single half-cell cathode channel of
proton exchange membrane (PEM) fuel cell. From practical point of view, it is necessary to put the appropriate number of cells
in a stack. Hence, the above study on a single half-cell is extended to a stack of channels. Due to stacking, the assumption
of uniform flow distribution would no longer hold true. Therefore, the channel flow-maldistribution is considered. The water
formed at the active surface due to the electrochemical reaction diffuses through the porous layer and eventually enters the
gas flow duct. The higher gas velocities in the duct result in faster water vapour removal which leads to a lower value of
water vapour into the duct and hence a lower Nusselt number. 相似文献
998.
Jaume Llibre Paulo R. da Silva Marco A. Teixeira 《Journal of Dynamics and Differential Equations》2007,19(2):309-331
Singular perturbations problems in dimension three which are approximations of discontinuous vector fields are studied in
this paper. The main result states that the regularization process developed by Sotomayor and Teixeira produces a singular
problem for which the discontinuous set is a center manifold. Moreover, the definition of sliding vector field coincides with
the reduced problem of the corresponding singular problem for a class of vector fields.
相似文献
999.
Morphological measurements in 3D for pore space characterization (connectivity pore-body/throat classification, shape factors,
virtual fluid intrusion) are based on computed intensive digital-thinning operations for skeletonization and medial axis extraction
from 3D digital images. We present an alternative method that is measurably faster and allows sub-voxel definition of the
pore space network. The method allows extracting—based on morphological considerations only—the centered and shortest stream-lines—i.e.,
the paths—to follow in order to go through the pore space from one given point to another and to exit. In addition the method
penalizes long and narrow pore-throats in favor of short stubby/ones—i.e., it has a built-in exemplification capacity. It
exploits well-established mathematical methods successfully applied in medical endoscopy. 相似文献
1000.
Héctor Gómez Ignasi Colominas Fermín Navarrina Manuel Casteleiro 《Heat and Mass Transfer》2008,45(2):219-226
A number of contributions have been made during the last decades to model pure-diffusive transport problems by using the so-called hyperbolic diffusion equations. These equations are used for both mass and heat transport. The hyperbolic diffusion equations are obtained by substituting the classic constitutive equation (Fick’s and Fourier’s law, respectively), by a more general differential equation, due to Cattaneo (C R Acad Sci Ser I Math 247:431–433, 1958). In some applications the use of a parabolic model for diffusive processes is assumed to be accurate enough in spite of predicting an infinite speed of propagation (Cattaneo, C R Acad Sci Ser I Math 247:431–433, 1958). However, the use of a wave-like equation that predicts a finite velocity of propagation is necessary in many other calculations. The studies of heat or mass transport with finite velocity of propagation have been traditionally limited to pure-diffusive situations. However, the authors have recently proposed a generalization of Cattaneo’s law that can also be used in convective-diffusive problems (Gómez, Technical Report (in Spanish), University of A Coruña, 2003; Gómez et al., in An alternative formulation for the advective-diffusive transport problem. 7th Congress on computational methods in engineering. Lisbon, Portugal, 2004a; Gómez et al., in On the intrinsic instability of the advection–diffusion equation. Proc. of the 4th European congress on computational methods in applied sciences and engineering (CDROM). Jyväskylä, Finland, 2004b) (see also Christov and Jordan, Phys Rev Lett 94:4301–4304, 2005). This constitutive equation has been applied to engineering problems in the context of mass transport within an incompressible fluid (Gómez et al., Comput Methods Appl Mech Eng, doi: 10.1016/j.cma.2006.09.016, 2006). In this paper we extend the model to compressible flow problems. A discontinuous Galerkin method is also proposed to numerically solve the equations. Finally, we present some examples to test out the performance of the numerical and the mathematical model. 相似文献