Numerical modelling of detonation performance

1992 ◽  
Vol 339 (1654) ◽  
pp. 419-429 ◽  
Keyword(s):  
Steady State ◽  
Reaction Zone ◽  
Fluid Dynamic ◽  
Detonation Front ◽  
Wave Structure ◽  
Detonation Performance ◽  
Primary Data ◽  
Reactive Flow ◽  
Temperature Dependent ◽  
Flow Models

Detonation performance is defined in terms of the steady state wave structure of the detonation front, and the initiation behaviour of the explosive. Some common techniques for modelling detonation performance are described, based on semi-analytic hydrodynamic and computational fluid dynamic reactive flow models. Accurate modelling of detonation performance is shown to require resolution of the reaction zone in the explosive, for non-ideal and for intrinsically unreactive systems. The ability of detonation models to predict steady state and initiation performance is discussed. Examples of resolve reaction zone models of explosives of varying degrees of ideality are presented. The sensitivity of predictions to primary data is examined for steady state reaction zone modelling of the insensitive explosive PBX W115, and Composition B3. Future directions for development of reactive flow models are examined. Particular emphasis is drawn to the need for more detailed temperature dependent kinetic schemes, and the inclusion of more detailed reaction geometries in such flow models.

scholarly journals Accumulation of Non-steroidal Anti-inflammatory Drugs by Gingival Fibroblasts

2006 ◽  
Vol 85 (5) ◽  
pp. 452-456 ◽  
Author(s):  
M.M. Zavarella ◽  
O. Gbemi ◽  
J.D. Walters
Keyword(s):  
Steady State ◽  
Connective Tissue ◽  
Inflammatory Mediator ◽  
Dependent Manner ◽  
Gingival Fibroblasts ◽  
Temperature Dependent ◽  
Tnf Α ◽  
Steady State Levels ◽  
Inflammatory Drugs ◽  
Anti Inflammatory

Non-steroidal anti-inflammatory drugs (NSAIDs) are used to manage pain and inflammatory disorders. We hypothesized that gingival fibroblasts actively accumulate NSAIDs and enhance their levels in gingival connective tissue. Using fluorescence to monitor NSAID transport, we demonstrated that cultured gingival fibroblasts transport naproxen in a saturable, temperature-dependent manner with a Km of 127 μg/mL and a Vmax of 1.42 ng/min/μg protein. At steady state, the intracellular/extracellular concentration ratio was 1.9 for naproxen and 7.2 for ibuprofen. Naproxen transport was most efficient at neutral pH and was significantly enhanced upon cell treatment with TNF-α. In humans, systemically administered naproxen attained steady-state levels of 61.9 μg/mL in blood and 9.4 μg/g in healthy gingival connective tissue, while ibuprofen attained levels of 2.3 μg/mL and 1.5 μg/g, respectively. Thus, gingival fibroblasts possess transporters for NSAIDs that are up-regulated by an inflammatory mediator, but there is no evidence that they contribute to elevated NSAID levels in healthy gingiva.

Charge Generation in PbS Quantum Dot Solar Cells Characterized by Temperature-Dependent Steady-State Photoluminescence

ACS Nano ◽  
2014 ◽  
Vol 8 (12) ◽  
pp. 12814-12825 ◽  
Author(s):  
Jianbo Gao ◽  
Jianbing Zhang ◽  
Jao van de Lagemaat ◽  
Justin C. Johnson ◽  
Matthew C. Beard
Keyword(s):  
Solar Cells ◽  
Steady State ◽  
Quantum Dot ◽  
Temperature Dependent ◽  
Charge Generation ◽  
Quantum Dot Solar Cells ◽  
Pbs Quantum Dot

Optimization of fluid characteristics in the main nozzle of an air-jet loom

2021 ◽  
pp. 004051752110395
Author(s):  
Xinlei Huang ◽  
Lee Michael Clemon ◽  
Mohammad Saidul Islam ◽  
Suvash C. Saha
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Sudden Expansion ◽  
Dynamic Features ◽  
Original Design ◽  
Flow Models ◽  
Air Jet ◽  
Acceleration Tube ◽  
Air Jet Loom ◽  
Fluid Characteristics

As part of the propulsion system, the fluid dynamic features of the main nozzle can immediately affect the stability and efficiency of an air-jet loom. This study aims to optimize the fluid characteristics in the main nozzle of an air-jet loom. To investigate ways of weakening the effect of airflow congestion and backflow phenomenon occurring in the sudden expansion region, the computational fluid dynamics method is employed. Three-dimensional turbulence flow models for a regular main nozzle and 12 prototypes with different nozzle core tip geometry are built, simulated, and analyzed to get the optimum performance. Furthermore, a set of modified equations that consider the direction of airflow are proposed for better estimation of the friction force applied by the nozzle. The result shows that the nozzle core tip's geometry has a significant influence on the internal airflow, affecting the acceleration tube airflow velocity, turbulence intensity, and backflow strength of the sudden expansion region, and other critical fluid characteristics as well. Several proposed models have succeeded in reducing the backflow and outperforming the original design in many different aspects. Models A-60 and C-P, in particular, manage to increase the propulsion force by 37.6% and 20.2% in the acceleration tube while reducing the maximum backflow by 57.1% and 52.2%, respectively. These simulation results can provide invaluable information for the future optimization of the main nozzle.

On Assessing the Quality of Particle Tracking Through Computational Fluid Dynamic Models

2002 ◽  
Vol 124 (2) ◽  
pp. 166-175 ◽  
Author(s):  
Mauro Tambasco ◽  
David A. Steinman
Keyword(s):  
Velocity Field ◽  
Computational Fluid Dynamic ◽  
Particle Deposition ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Mass Conservation ◽  
Carotid Bifurcation ◽  
Quantitative Information ◽  
Flow Models ◽  
Path Dependent

Quantification of particle deposition patterns, transit times, and shear exposure is important for computational fluid dynamic (CFD) studies involving respiratory and arterial models. To numerically compute such path-dependent quantities, it is necessary to employ a Lagrangian approach where particles are tracked through a pre-computed velocity field. However, it is difficult to determine in advance whether a particular velocity field is sufficiently resolved for the purposes of tracking particles accurately. Towards this end, we propose the use of volumetric residence time (VRT)—previously defined for 2-D studies of platelet activation and here extended to more physiologically relevant 3-D models—as a means of quantifying whether a volume of Lagrangian fluid elements (LFE’s) seeded uniformly and contiguously at the model inlet remains uniform throughout the flow domain. Such “Lagrangian mass conservation” is shown to be satisfied when VRT=1 throughout the model domain. To demonstrate this novel concept, we computed maps of VRT and particle deposition in 3-D steady flow models of a stenosed carotid bifurcation constructed with one adaptively refined and three nominally uniform finite element meshes of increasing element density. A key finding was that uniform VRT could not be achieved for even the most resolved meshes and densest LFE seeding, suggesting that care should be taken when extracting quantitative information about path-dependent quantities. The VRT maps were found to be useful for identifying regions of a mesh that were under-resolved for such Lagrangian studies, and for guiding the construction of more adequately resolved meshes.

scholarly journals Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate

2016 ◽  
Vol 37 (3) ◽  
pp. 109-138 ◽  
Author(s):  
Henryk Bieliński
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Vertical Section ◽  
Volumetric Flow Rate ◽  
Working Fluid ◽  
Two Phase ◽  
Generalized Model ◽  
Flow Models ◽  
Theoretical Predictions ◽  
The One

AbstractThe current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the lower vertical section and a condenser on the upper vertical section. The one-dimensional homogeneous and separated two-phase flow models were used in calculations. The latest minichannel heat transfer correlations available in literature were applied. A numerical analysis of the volumetric flow rate in the steady-state has been done. The experiment was conducted on a specially designed test apparatus. Ultrapure water was used as a working fluid. The results show that the theoretical predictions are in good agreement with the measured volumetric flow rate at steady-state.

Reactive flow models of the Anarraaq Zn–Pb–Ag deposit, Red Dog district, Alaska

2008 ◽  
Vol 43 (7) ◽  
pp. 735-757 ◽  
Author(s):  
Christian Schardt ◽  
Grant Garven ◽  
Karen D. Kelley ◽  
David L. Leach
Keyword(s):  
Reactive Flow ◽  
Flow Models
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