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  • 1
    Electronic Resource
    Electronic Resource
    Numerical simulation of detonation reignition in H $_2$-O $_2$ mixtures in area expansions (2000)
    Springer
    Shock waves 10 (2000), S. 33-41 
    Details
    ISSN: 1432-2153
    Keywords: Key words: Detonation reignition, H $_2$-O $_2$ detonations, Multidimensional detonation dynamics, Transmitted detonations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract. Time-dependent, two-dimensional, numerical simulations of a transmitted detonation show reignition occuring by one of two mechanisms. The first mechanism involves the collision of triple points as they expand along a decaying shock front. In the second mechanism ignition results from the coalescence of a number of small, relatively high pressure regions left over from the decay of weakened transverse waves. The simulations were performed using an improved chemical kinetic model for stoichiometric H $_2$ -O $_2$ mixtures. The initial conditions were a propagating, two-dimensional detonation resolved enough to show transverse wave structure. The calculations provide clarification of the reignition mechanism seen in previous H $_2$ -O $_{2}$ -Ar simulations, and again demonstrate that the transverse wave structure of the detonation front is critical to the reignition process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001930050177
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of cellular structure on detonation transmission (1996)
    Springer
    Shock waves 6 (1996), S. 119-129 
    Details
    ISSN: 1432-2153
    Keywords: Key words:Cellular structure, Reignition, Detonation, Numerical simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract. We present two-dimensional numerical simulations of the transmission of detonation from a rectangular channel into a larger volume. The simulations solve the Euler equations on a Cartesian grid using the method of Flux-Corrected Transport for the fluid equations and a two-step induction parameter model for the chemistry. We simulate detonation in a H $_2$ /O $_2$ /Ar mixture and use sufficient grid resolution to resolve the cellular structure of the detonation. When a planar detonation front without a resolved cellular structure expands into the larger volume, the reaction front separates from the shockfront and the detonation fails. When the planar front is perturbed to induce a quasi-regular cellular structure in the detonation, it again initially begins to fail, but now the presence of the transverse waves leads to reignition of the detonation in the larger volume. The form of this reignition shows striking similarities to the reignition of detonation which has been seen experimentally in H $_2$ /O $_2$ mixtures. We describe this reignition mechanism in detail, and also investigate the dependence of the reignition on the number of cells in the detonation front.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001930050028
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  • 3
    Electronic Resource
    Electronic Resource
    A Numerical Study of an Operator Splitting Method for Rotating Flows with Large Ageostrophic Initial Data (1999)
    Springer
    Theoretical and computational fluid dynamics 13 (1999), S. 143-159 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract: We propose an operator splitting method which is especially suitable for long-time integration of geophysical equations characterized by the presence of multiple-time scales and weak-operator splitting. The method is illustrated on the classical rotating shallow-water equations on a periodic domain with large ageostrophic (unprepared) initial data. The asymptotic splitting decomposes the solution into a first part which solves the quasigeostrophic equation; a second one which is the “slow” ageostrophic component of the flow; and a corrector. The particular decomposition we use ensures that the corrector is small for large rotation. By considering only the “slow” ageostrophic and quasigeostrophic components a numerical approximation to the shallow-water equations is derived that effectively removes the time-step restrictions caused by the presence of fast waves. The splitting is exact in the asymptotic limit of large rotation and includes the nonlinearity of the equations. Numerical examples are included. These examples demonstrate a significant reduction in the computational cost over direct numerical approximations of the shallow-water equations. We conclude with an outline of a general operator splitting method for more general primitive geophysical equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001620050012
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  • 4
    Electronic Resource
    Electronic Resource
    The potential of dried, low-hatch, decapsulated Artemia cysts for feeding prawn post-larvae (1998)
    Springer
    Aquaculture international 6 (1998), S. 421-440 
    Details
    ISSN: 1573-143X
    Keywords: Decapsulated Artemia cysts ; Leaching ; Post-larvae nutrition ; Prawn (Penaeus indicus) ; Survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Low-hatch, decapsulated Artemia cysts were assessed as feed for Penaeus indicus post-larvae (PL) 1–15 days old and the problems resulting from the incorporation of decapsulated cysts into compounded feeds were evaluated. Growth and survival of PL fed on decapsulated cysts (AC) were comparable with Artemia nauplii fed PL (control) and significantly (p 〈 0.05) higher than observed amongst PL fed on two granulated commercial diets (G150 and G300) or a commercial flake feed (AC-F) incorporating decapsulated cysts (80%). PL fed on artificial diets showed poor growth and delay in metamorphosis. However, survival of PL fed on AC-F was significantly higher (p 〈 0.05) than that observed amongst granulated feeds. Decapsulated cysts processed into a granulated feed (AC-G) or dried at 90°C (AC-90) also resulted in slow growth and survival when fed to PL. Overall, artificial feeds showed poor water stability and significantly higher leaching of soluble protein and carbohydrates than decapsulated cysts. AC-90 cysts also showed a high level of bursting and leaching of material. This indicates that low-hatch Artemia cysts retain a living membrane after commercial decapsulation and drying prevents loss of highly digestible nutrients, which allows PL growth equal to that on PL fed live Artemia nauplii. Survival of PL was negatively correlated with leaching of soluble protein (p 〈 0.05), but no correlation was observed for leaching of carbohydrates or between growth and loss of both soluble nutrients. Hence, availability of digestible protein is critical and may influence survival of early stages of post-larval development. Water stability of artificial feeds is an essential factor in promoting efficient nutrition of PL, but other aspects related to heating during processing of feeds also appear to have a deleterious effect on nutritional quality of compounded feeds. Commercially dried, encapsulated Artemia cysts from low-hatch strains remain alive and are highly nutritious for feeding early stages of post-larval prawn but even after death may support acceptable survival when incorporated into a flake diet. © Rapid Science Ltd. 1998
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009231417434
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of Algal Exudates and Bacteria on Growth and Survival of White Shrimp Larvae Fed Entirely on Microencapsulated Diets (1999)
    Springer
    Aquaculture international 7 (1999), S. 137-158 
    Details
    ISSN: 1573-143X
    Keywords: algal exudates ; bacterial balance ; larval culture ; microencapsulated diets ; white shrimp (Penaeus indicus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Intact microencapsulated protozoeal diets (MED), added to 5 μm filtered hatchery water at the recommended concentration of 4 mg L-1 gave no significant difference in bacterial numbers after 6 h, over a 48 h period compared to control groups in autoclaved hatchery water. Disruption of the MED resulted in a significant increase in bacterial numbers up to 12 h compared to controls with intact microcapsules. Protein leach rates were similar in sterile water and 5 μm filtered water, indicating that leaching was independent of microbial activity. MED leached significantly less dietary solubles compared to a microparticulate diet (MPD). There was no evidence to suggest significant attachment of bacteria to diet particles for at least 48 h. In low-quality water after algal blooms, survival of white shrimp (Penaeus indicus) larvae was poor when reared in both sterile and 5 μm filtered water. The addition of bacteria filtered from xenic algal cultures together with the algal exudates to such water gave significant improvements in survival to larvae fed MED in 5 μm filtered water but not in autoclaved culture water. Live algal diets promote high larval survival and growth irrespective of the inclusion of bacteria. It is suggested that algal exudates act as selective bacteriocides and total replacement of algae with MED requires a balanced bacterial community which can be attained at times from natural sea water, or when the natural bacterial community balance is disturbed, corrected by the use of algal exudates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009257902630
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