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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of engineering mathematics 31 (1997), S. 305-318 
    ISSN: 1573-2703
    Keywords: exact solution ; stagnation flow ; unsteady ; suction ; viscous
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract The viscous fluid motion generated by axisymmetric stagnation-point flow of strain rate a impinging on a flat plate oscillating in its own plane with velocity amplitude U0 and frequency ω, including uniform suction of strength W0 is considered. A coordinate decomposition transforms the full Navier-Stokes equations into a primary equation describing the steady flow and a secondary equation describing the unsteady motion coupled to the primary solution. The solution to the boundary-value problem is governed by two dimensionless groups: the suction parameter S = W0 √aν and the frequency parameter Ω = ω/a, where ν is the kinematic viscosity. Numerical integrations performed with a Runge-Kutta routine provide an exact solution to the Navier-Stokes equations. Values of the steady shear stress are found to agree with asymptotic results for large values of |S|, with S〉0 representing suction and S〈0 representing blowing. The magnitude and phase of the unsteady shear stress are given over a range of frequencies sufficient to recover analytical asymptotic results at large values of Ω. The unsteady shear stress lags the wall motion by π radians for Ω → 0 and by 5π/4 radians when Ω → ∞. Velocity profiles at selected parameter values during a period of plate oscillation are presented and discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Tropical animal health and production 27 (1995), S. 221-224 
    ISSN: 1573-7438
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1533-1543 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Small perturbation, linear, inviscid stability theory is developed and applied to coflowing chemically reacting jets. A necessary condition for the existence of axisymmetric and azimuthal instabilities is derived. The eigenfunction structure provides considerable insight into the underlying physical mechanism. In nonpremixed cases, high temperature tends to occur in regions where the shear layer tries to roll up; this reduces the available momentum, suppressing the growth of instabilities. It is found that chemical reaction during the growth of instabilities is unimportant, suggesting that this effect could be ignored in a viscous theory. Both nonpremixed and premixed flames in axisymmetric shear layers are generally more stable to small perturbations than in the corresponding cold case. However, while for nonpremixed flames the frequency of the most amplified wave decreases with increasing heat release, the opposite occurs for premixed cases.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 720-728 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The near field of a non-premixed flame in a low speed, coflowing axisymmetric jet is investigated numerically using full simulation. The time-dependent governing equations are solved by a second-order, explicit finite difference scheme and a single-step, finite rate model is used to represent the chemistry. Steady laminar flame results show the correct dependence of flame height on Peclet number and reaction zone thickness on Damköhler number. Forced simulations reveal a large difference in the instantaneous structure of scalar dissipation fields between nonbuoyant and buoyant cases. In the former, the scalar dissipation marks intense reaction zones, supporting the flamelet concept; however, results suggest that flamelet modeling assumptions need to be reexamined. In the latter, this correspondence breaks down, suggesting that modifications to the flamelet modeling approach are needed in buoyant turbulent diffusion flames.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plasma chemistry and plasma processing 16 (1996), S. 417-448 
    ISSN: 1572-8986
    Keywords: Flame-assisted plasma ; variable properties ; diffusion ; laser-induced fluorescence ; electrostatic probe ; current/voltage characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A well-characterized flame-assisted plasma was developed to understand the role of flow nonuniformities and plasma/wall interactions in plasma devices for use in validation of laser-based Doppler shift spectroscopic methods. A hydrogen/oxygen capillary diffusion flame burner was used as a plasma source, with barium seeded into the reactants to provide a source of ions and electrons. For analysis the plasma was assumed to be a stationary, partially ionized, collision dominated, thermal plasma consisting of barium ions, electrons, and neutrals between two parallel-plate electrodes. The plasma was examined in terms of the continuum equations for ions and electrons, together with Poisson's equation to predict spatial profiles of electron and positive ion density and potential as functions of applied potential. First an analytic solution based on constant plasma properties and negligible difusion was introduced. The model was then extended by including effects of diffusion and variable plasma properties. Experimentally, current/voltage characteristics of the plasma were measured conventionally, relative ion concentration and temperature were measured with laser-induced fluorescence, and local potential distribution was measured using an electrostatic probe. The diffusionless theory predicted well the bulk behavior of the plasma, but not the correct spatial distributions of ion concentration and potential. The extended model produced a more satisfactory fit to the data. At conditions of 1.4 equivalence ratio, 70 torn pressure, 300 ppm seed concentration, and 100–400 V applied potentials, electric fields of the order of 102, 103 V/cm were observed near the powered electrode, and of few tens of V/cm in the hulk of tire plasma. The field strength in the sheath ensures the operation of the Doppler shift diagnostics, once the recommendations tor LIF signal detectability are fulfilled.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature medicine 3 (1997), S. 1117-1123 
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The HIV-1 accessory gene product Vpr can influence viral pathogenesis by affecting viral replication as well as host cell transcription and proliferation. We have investigated the effects of Vpr on host cell activation and confirm that it influences cellular proliferation. However, we have also ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Sound and Vibration 36 (1974), S. 179-189 
    ISSN: 0022-460X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Sound and Vibration 77 (1981), S. 149-163 
    ISSN: 0022-460X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Sound and Vibration 36 (1974), S. 285-295 
    ISSN: 0022-460X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Sound and Vibration 41 (1975), S. 311-320 
    ISSN: 0022-460X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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