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  • 1
    Electronic Resource
    Electronic Resource
    Erratum: "Behavior of streamwise rib vortices in a three-dimensional mixing layer'' [Phys. Fluids A 5, 1694 (1993)] (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 3013-3013 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858710
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  • 2
    Electronic Resource
    Electronic Resource
    Behavior of streamwise rib vortices in a three-dimensional mixing layer (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 1694-1702 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure and behavior of a streamwise rib vortex in a direct numerical simulation of a time-developing three-dimensional incompressible plane mixing layer is examined. Where the rib vortex is being stretched, the vorticity vector is primarily directed in the vortex axial direction and the radial and azimuthal velocity distribution is similar to that of a Burgers vortex. In the region where the vortex stretching is negative, there is a change in the local topology of the vortex. The axial flow is decelerated and a negative azimuthal component of vorticity is induced. These features are characteristic of vortex breakdown. The temporal evolution of the rib vortex is similar to the evolution of an axisymmetric vortex in the early stages of vortex breakdown. The effect of vortex breakdown on other parts of the flow is, however, not as significant as the interaction between the rib vortex and other vortical structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858846
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  • 3
    Electronic Resource
    Electronic Resource
    Unsteady swirling flow in an enclosed cylinder with reflectional symmetry (1995)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 7 (1995), S. 2700-2714 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A numerical investigation of the multiple stable solutions found in confined swirling flows is presented. The flows consist of fluid in a completely filled cylinder driven by the constant corotation of the two end walls. When reflectional symmetry at the cylinder half-plane is imposed, the flow corresponds to that in a cylinder of half the height driven by the bottom end wall, with the top surface being flat and stress-free. Comparisons with available experiments in this case are made and the observed toroidal recirculation zones attached to the free surface are described in terms of secondary motions induced by the bending of vortex lines. Calculations are also presented where the reflectional symmetry is not imposed and the possibility of the flow breaking this symmetry is discussed. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868717
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  • 4
    Electronic Resource
    Electronic Resource
    On the bifurcation structure of axisymmetric vortex breakdown in a constricted pipe (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 3683-3693 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The bifurcation structure is presented for an axisymmetric swirling flow in a constricted pipe, using the pipe geometry of Beran and Culick [J. Fluid Mech. 242, 491 (1992)]. The flow considered has been restricted to a two-dimensional parameter space comprising the Reynolds number Re and the relative swirl V0 of the incoming swirling flow. The bifurcation diagram is constructed by solving the time-dependent axisymmetric Navier–Stokes equations. The stability of the steady results presented by Beran and Culick, obtained from a steady axisymmetric Navier–Stokes code, has been confirmed. Further, the steady solution branch has also been extended to much larger V0 values. At larger V0, a stable unsteady solution branch has been identified. This unsteady branch coexists with the previously found stable steady solution branch and originates via a turning point bifurcation. The bifurcation diagram is of the type described by Benjamin [Proc. R. Soc. London Ser. A 359, 1 (1978)] as the canonical unfolding of a pitchfork bifurcation. This type of bifurcation structure in the two-dimensional parameter space (Re,V0), suggests the possibility of hysteresis behavior over some part of parameter space, and this is observed in the present study. The implications of this on the theoretical description of vortex breakdown and the search for a criterion for its onset are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868359
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  • 5
    Electronic Resource
    Electronic Resource
    Orbital free ab initio molecular dynamics study of liquid Al near melting (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 2373-2376 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The orbital free ab initio molecular dynamics method is applied to study the static and dynamic structure of liquid Al near the triple point. The method uses a new kinetic energy functional, along with a local pseudopotential constructed within the same kinetic energy functional. The results obtained for the dynamic structure factor are compared with recent experimental data. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1389473
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  • 6
    Electronic Resource
    Electronic Resource
    Flow between a stationary and a rotating disk shrouded by a co-rotating cylinder (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 8 (1996), S. 2605-2613 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Boundary layers on stationary and rotating disks have received much attention since von Kármán's [Z. Angew. Math. Mech. 1, 233 (1921)] and Bödewadt's [Z. Angew. Math. Mech. 20, 241 (1940)] studies of the cases with disks of infinite radius. Theoretical treatments have focused on similarity treatments leading to conflicting ideas about existence and uniqueness, and where self-similar solutions exist, whether they are physically realizable. The coupling between the boundary layer flows and the interior flow between them, while being of practical importance in a variety of situations such as turbomachinery and ocean circulations, is not well understood. Here, a numerical treatment of the axisymmetric Navier–Stokes equations, together with some experiments for the case of finite stationary and rotating disks bounded by a co-rotating sidewall is presented. We show that in the long time limit, solutions are steady and essentially self-similar. Yet the transients are not. In particular, axisymmetric waves propagate in the stationary disk boundary layer when the vortex lines entering the boundary layer develop inflection points, and there are subsequent eruptions of vortical flow out of the boundary layer deep into the interior at large Reynolds numbers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.869047
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  • 7
    Electronic Resource
    Electronic Resource
    MONITORING SUSPENDED PARTICULATE MATTER IN PUERTO RICO: FIELD MEASUREMENTS AND REMOTE SENSING (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 30 (1994), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The spatial distribution of suspended particulatematter (SPM) was estimated in Mayagüez Bay on the west coast of Puerto Rico by using traditional ship board measurements and remotely sensed data acquired over four days during January 1990. This effort was part of a joint project between NASA and the University of Puerto Rico to develop techniques to monitor the water quality of a Caribbean coastal zone. This paper presents the methods and algorithms developed to map and analyze short term changes in the source and spatial distribution of SPM in Mayagüez Bay by using remotely sensed data acquired by the Calibrated Airborne Multispectral Scanner (CAMS). A PC-based data acquisition system was developed to record continuous ship measurements of select in- water variables. Spectral reflectances derived from CAMS red and near-IR data were corrected for atmospheric effects and then used to generate maps of SPM. These maps displayed SPM plumes associated with the mouths of the bay's three river systems. Significant day-to-day differences in the spatial characteristics were observed, suggesting that changes in river discharge occurred. However, an analysis of estimated river discharge, sediment yield, local wind field, and thermal river plume indicates that observed sediment plumes result primarily from wind-driven resuspension events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1994.tb03290.x
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  • 8
    Electronic Resource
    Electronic Resource
    ADRENOCORTICOTROPIN AND PLASMA ALDOSTERONE CONCENTRATION AND DEOXYCORTICOSTERONE IN MAN (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 297 (1977), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1977.tb41867.x
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  • 9
    Electronic Resource
    Electronic Resource
    Evolution of an initially columnar vortex terminating normal to a no-slip wall (2000)
    Springer
    Experiments in fluids 29 (2000), S. 309-321 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The early evolution of an initially columnar vortex normal to a solid wall was examined. The vortex was generated by a pair of flaps in a water tank. Detrimental effects from the wall during the vortex generation were avoided by producing the vortex normal to a free surface and subsequently bringing a horizontal plate into contact with the surface. Digital particle image velocimetry (DPIV) measurements of the velocity and vorticity, together with laser induced fluorescence (LIF) visualizations, in a meridional plane revealed a toroidal structure with the appearance of an axisymmetric vortex breakdown bubble. Agreement was found between the measurements and numerical simulations of the axisymmetric Navier–Stokes equations. The results show that the flow in the effusive corner region is dominated by a Bödewadt-type spatially oscillatory boundary layer within the core region and a potential-like vortex boundary layer at large radii. The toroidal structure results from the interaction between these two boundary layers, leading to the roll up of a dominant shear layer within the Bödewadt structure, and does not develop from the columnar vortex itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003489900086
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  • 10
    Electronic Resource
    Electronic Resource
    Thermal behaviour of bioactive alkaline-earth silicophosphate glasses (1995)
    Springer
    Journal of materials science 6 (1995), S. 353-359 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The thermal behaviour (sinterability and first crystallization) of a series of alkaline-earth silicophosphate glasses has been studied by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The samples were prepared from a base bioactive glass of the system CaO−P2O5−SiO2−CaF2, by (a) slightly changing the F/O ratio; (b) replacing part of the CaO by SrO or MgO; and (c) increasing the total alkaline earth concentration by MgO additions. The results show that the addition of MgO is the most effective way of improving sinterability. In these samples, a decrease of the glass transition temperature, together with an increase in the temperature of the first crystallization, is observed. The difference between both temperatures is proposed to be an adequate indicator of the sinterability. The initial stages of the first crystallization (which produces an oxo-fluorapatite), and its composition dependence, are discussed in terms of the results of sinterability, and the classical theory of nucleation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120304
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