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403 results on '"Coimbra C"'

87. Variable Order Modeling of Diffusive-convective Effects on the Oscillatory Flow Past a Sphere.

Author

PEDRO, H. T. C., KOBAYASHI, M. H., PEREIRA, J. M. C., and COIMBRA, C. F. M.

Subjects
DRAG (Aerodynamics), VISCOUS flow, FLUID dynamics, REYNOLDS number, CALCULUS, VISCOSITY
Abstract

This work advances our understanding of the drag force acting on a particle due to the oscillatory flow of a viscous fluid with finite Reynolds and Strouhal numbers. The drag force is is determined using the novel concept of variable order (VO) calculus, where the order of derivative can vary with the parameters and variables, according to the dynamics of the flow. Using the VO formulation we determine: (i) The region of validity of Tchen's equation for oscillatory flow, (ii) the region where the order of the derivative is fractional but constant, and (iii) the region where the strong non-linearity of the flow requires a variable order derivative to account for the increased complexity of the flow. [ABSTRACT FROM AUTHOR]

Published
2008
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96. History effects on the viscous motion of acoustically forced particles.

Author

Allen, J. S., Kobayashi, M. H., and Coimbra, C. F. M.

Subjects
PARTICLES, VISCOSITY, EIGENFUNCTIONS, MATHEMATICAL functions, MOTION
Abstract

We examine memory viscous effects on the motion of a particle in the vicinity of nodal points. The Basset history force has a fractional derivative dependence of order 3/2 on the particle displacement, and its contribution to the dynamics of acoustically forced particles is demonstrated for typical conditions occurring in acoustic separation devices. The inclusion of the Basset history force in the formulation has the net effect of changing the eigenfunctions of the problem from exponential to Mittag-Leffler functions, thus affecting the overall balance of forces considered. [ABSTRACT FROM AUTHOR]

Published
2006
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97. D1S80 locus variability in South American Indians

Author

Hutz, M. H., Mattevi, V. S., Callegari-Jacques, S. M., Salzano, F. M., Coimbra, C. E. A., Santos, R. V., Carnese, R. F., Goicoechea, A. S., and Dejean, C. B.

Abstract

We have studied the hypervariable D1S80 locus in 185 individuals from five South American Indian tribes, integrating these results with previous investigations. Three alleles (*18, *24 and *30) were common to all tribes, but their frequencies varied between northern and southern populations. Brazilian tribes have a high frequency of *30 (average 35%) while in Argentinian and Chilean Indian populations this allele is present, on average, in 7% of the chromosomes only. Allele *24, the most common in other ethnic groups, was observed in 10% and 25% of northern and southern Amerindians respectively. Genetic distance and dendrogram analyses placed the Argentinian and Chilean tribes closer to Brazilian Caucasians, suggesting non-Indian admixture among them.

Published
1997
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