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  • 1
    Electronic Resource
    Electronic Resource
    The influence of radiative heat transfer upon the collapse of a cylindrical shock wave (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 13 (2001), S. 2682-2692 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the effects of thermal radiation upon the classical self-similar solution of the collapse of cylindrical shock waves in inviscid, ideal gas with a constant ratio of specific heats. The gas is considered to be optically thick and the shock front to be opaque. The ambient gas ahead of the shock front is assumed to be uniform and at rest and its counterpressure concerning the motion of the shock front is neglected. In order to investigate the deviation from the classical adiabatic solution caused only by a small amount of radiation, the shock front in the nonadiabatic case fulfills the same conditions as the shock front in the adiabatic case, except for the fact that in the nonadiabatic case heat is released at the shock front. For different adiabatic exponents self-similar solutions have been obtained determining the eigenvalues and the profiles of the flow variables. The influence of radiation is shown through variation of the mean free path of radiation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286596
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  • 2
    Electronic Resource
    Electronic Resource
    The propagation of spherical and cylindrical shock waves in real gases (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 2154-2164 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Real gas and heat transfer effects are included in the solution of the blast wave resulting from a point or line explosion. Due to the extremely high temperatures, particularly at the beginning of shock propagation, the assumption of perfect gas is not valid. The equation of state takes into account the high temperature effects of vibration, dissociation, electronic excitation, and ionization, as well as the intermolecular forces at high pressures. The computation of the flow problem is carried out using the method of characteristics which has been modified to the effects of radiative and conductive heat transfer. The results show considerable deviation in the initial stages of the explosion from the perfect gas solution, in particular the temperature profiles and the thermodynamic state immediately behind the front.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868218
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  • 3
    Electronic Resource
    Electronic Resource
    Shear stress calculation in asymmetric turbulent flows: A combined ARS-model
    Amsterdam : Elsevier
    Fluid Dynamics Research 14 (1994), S. 289-311 
    Details
    ISSN: 0169-5983
    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
    URL: http://linkinghub.elsevier.com/retrieve/pii/0169-5983(94)90038-8
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  • 4
    Electronic Resource
    Electronic Resource
    Quasi-similar solutions for blast waves with internal heat transfer effects
    Amsterdam : Elsevier
    Fluid Dynamics Research 8 (1991), S. 273-285 
    Details
    ISSN: 0169-5983
    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
    URL: http://linkinghub.elsevier.com/retrieve/pii/0169-5983(91)90047-M
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  • 5
    Electronic Resource
    Electronic Resource
    Blast waves in inhomogeneous atmospheres including real gas and heat transfer effects*
    Amsterdam : Elsevier
    Fluid Dynamics Research 14 (1994), S. 191-216 
    Details
    ISSN: 0169-5983
    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
    URL: http://linkinghub.elsevier.com/retrieve/pii/0169-5983(94)90028-0
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  • 6
    Electronic Resource
    Electronic Resource
    Blast waves in inhomogeneous atmospheres with counterpressure and heat transfer effects (1993)
    Springer
    Shock waves 3 (1993), S. 83-94 
    Details
    ISSN: 1432-2153
    Keywords: Blast waves ; Isothermal atmospheres ; Point explosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract The study on blast waves in cold exponential atmospheres by Bach, Kuhl, and Oppenheim is extended to provide a uniformly valid numerical solution of a point explosion problem in isothermal exponential atmospheres with finite temperature at the centre. This is achieved initially by solving the equations of motion with the help of a perturbation technique which takes into account thermal radiation and heat conduction. Whereas the extended perturbation solution for the strong shock regime (i.e. short times after initiation) serves as a starting solution for the numerical integration, the solution using the method of characteristics is valid for the whole flow field since counterpressure effects and energy losses at the front are not neglected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02115888
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  • 7
    Electronic Resource
    Electronic Resource
    Propagation of blast waves with exponential heat release and internal heat conduction and thermal radiation (1993)
    Springer
    Shock waves 3 (1993), S. 95-104 
    Details
    ISSN: 1432-2153
    Keywords: Chapman-Jouguet detonation ; Explosion ; Heat conduction ; Numerical results ; Reactive blast waves ; Thermal radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract The problem of reactive blast waves in a combustible gas mixture, where the heat release at the detonation front decays exponentially with the distance from the center, is analyzed. The central theme of the paper is on the propagation of reactive blast into a uniform, quiescent, counterpressure atmosphere of a perfect gas with constant specific heats. The limiting cases of Chapman-Jouguet detonation waves are considered in the phenomenon of point explosion. In order to deal with this problem, the governing equations including thermal radiation and heat conduction were solved by the method of characteristics using a problem-specific grid and a series expansion as start solution. Numerical results for the distribution of the gas-dynamic parameters inside the flow field are shown and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02115889
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Numerical solution for spherical laser-driven shock waves (1998)
    Springer
    Shock waves 8 (1998), S. 139-147 
    Details
    ISSN: 1432-2153
    Keywords: Key words:Laser radiation, Variable energy blasts, Non-self-similar flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract. The history of the flow behind a laser-driven shock is investigated in the context of variable energy blast waves. Thereby the total laser energy absorbed by the blast is assumed to vary proportionally to some power of time. Due to the high temperatures and pressures occurring in the initial phase of the flow a real gas model has been employed. It accounts for vibration, dissociation, electronic excitation, ionization and intermolecular forces. Radiative and conductive heat transfer are considered as well. The numerical computations were carried out using the method of characteristics. A self-similar strong shock solution serves as initial condition. It turns out that the exponent which determines the time-dependent addition of energy at the shock front is limited for physical reasons. The computed far-field solutions expand the temporal scope of the self-similar solution domain, which has been the main subject of the classical literature, into the non-self-similar domain at late time. The differences between the solutions obtained for real gas and perfect gas are less significant than in the case of the classical point explosion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001930050107
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  • 9
    Electronic Resource
    Electronic Resource
    Numerical simulation of a two-dimensional turbulent wall jet in an external stream (2000)
    Springer
    Forschung im Ingenieurwesen 66 (2000), S. 31-39 
    Details
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Zusammenfassung Bei turbulenten Wandstrahlen tritt zwischen den Punkten maximaler Geschwindigkeit und verschwindender Schubspannung ein Bereich mit negativer Produktion von kinetischer Turbulenzenergie auf. Viele Turbulenzmodelle können diese für die Beschreibung der turbulenten Strömung wichtige Eigenschaft nicht wiedergeben. Durch die Kombination einer erweiterten Schubspannungsbeziehung mit einem k–ɛ Modell oder einem algebraischen Reynoldsschen Spannungsmodell entsteht ein Modell, mit dem es möglich ist, diese physikalische Eigenschaft zu zeigen. Dieses Turbulenzmodell beschreibt auch die Strömung in Wandnähe und liefert bei wesentlich kürzeren Rechenzeiten ähnliche Ergebnisse wie ein volles Reynoldssches Spannungsmodell.
    Notes: Abstract Turbulent wall jets possess a region with negative production of turbulent kinetic energy between the points of maximum velocity and vanishing shear stress. This characteristic feature cannot be shown with many turbulence models. The use of an extended expression for the primary turbulent shear stress together with a k–ɛ or an algebraic Reynolds stress model results in a model which can show this physical property. Computed results obtained with this concept are compared with measurements and results obtained with the standard k–ɛ model and a full Reynolds stress closure. It is shown that the computed results with the present and the Reynolds stress model are of similar quality. However, the Reynolds stress solution is more costly in computing time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100100000039
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  • 10
    Electronic Resource
    Electronic Resource
    Numerical calculation of fully developed turbulent flow in curved channels: An extended algebraic Reynolds-stress model (2000)
    Springer
    Forschung im Ingenieurwesen 66 (2000), S. 138-146 
    Details
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Zusammenfassung Die Erweiterung eines algebraischen Spannungsmodells mit Hilfe einer neuen Beziehung fürdie turbulente Schubspannung zur Erfassung negativer Produktion kinetischer Turbulenzenergie, die in Strömungen durch gekrümmte Kanäle im Bereich zwischen Geschwindigkeitsmaximum und verschwindender Schubspannung auftritt, ist Gegenstand der vorliegenden Arbeit. Die sogenannte Energieumkehr kann von vielen Turbulenzmodellen, welche sich auf den Wirbelviskositätsansatz gründen, nicht erfaßt werden. Die Berechnungen werden für die vollentwickelte Strömung in Kanälen mit rechteckigem Querschnitt von großem Seitenverhältnis bei schwacher und starker Krümmung ausgeführt. Die Ergebnisse werden sowohl mit verschiedenen Modellrechnungen als auch mit Meßergebnissen verglichen. Die Genauigkeit der mit dem vorliegenden Modell erhaltenen Ergebnisse ist mit der eines Reynoldsschen Spannungsmodells vergleichbar. Letzteres beansprucht aber eine ungleich größere Rechenzeit und ist somit weitaus kostspieliger.
    Notes: Abstract The primary objective of the paper is to extend an algebraic Reynolds-stress model including a new expression for the turbulent shear stress, in order to describe the negative production of turbulent kinetic energy appearing in curved channel flows in a region between the points of maximum velocity and vanishing shear stress. This so-called energy reversal cannot be captured by the majority of turbulence models with conventional eddy-viscosity formulation. Computations are made for fully developed flows in channels of rectangular cross section and large aspect ratio with mild and strong curvature. The results are compared with different model predictions and experimental data reported in the literature. In the cases considered, the accuracy of present model predictions is comparable to that of a Reynolds-stress model. The latter, however, requires much more computing time and is thus more costly than the model here proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100100000047
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