This study focused on kinetic modeling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic reaction steps, as exemplified by the practical kinetic analysis of the experimental kinetic curves for the thermal decomposition of molten ammonium dinitramide (ADN). It is known that the thermal decomposition of ADN occurs as a consecutive two step mass-loss proc...

This study assesses the sensitivity of numerical results of air flow modelling within an urban environment to the six different turbulence models applied in a specific case of a studied staggered cross-road. The principal parameters investigated in this comparison are position of centres of vortices within a street canyon, two components of the spatial velocity vector, turbulent kinetic energy,...

The possibility of a dynamical core helium Ñash has been studied with two-dimensional hydrodynamic simulations using three separate turbulence models for the treatment of time-dependent convection. Two of these are simple algebraic eddy viscosity models. The third model involves a separate equation for the turbulent kinetic energy density, which then feeds into an expression for the eddy viscos...

The flow field has significantly impact on seeding performance in the suction seeding device. A three-dimensional, incompressible, viscous, RNG turbulence model and the SIMPLE method were used by computational fluid dynamics(CFD), and the flow fields of suction cylinder-seeder with different socket’s radiuses were simulated by Fluent. When vacuum is 4kPa and productivity is 350 trays/h, the sim...

Compressibility may strongly reduce the redistribution of turbulent kinetic energy. The question of how such effects can be taken into account in turbulence models is addressed here. First, a corresponding stochastic turbulence model is developed on the basis of a simplification of the generalized Langevin model for turbulent velocities. This model is then reduced to a deterministic model that ...

The dissipation rate transport equation remains the most uncertain part of turbulence modeling. The difficulties are increased when external agencies like rotation prevent straightforward dimensional analysis from determining the correct form of the modelled equation. In this work, the dissipation rate transport equation and subgrid scale models for rotating turbulence are derived from an analy...

Kinetic Monte Carlo simulations are used to investigate nucleation of two-dimensional islands on a substrate with nanoscale patterning. The patterned substrate is incorporated into a basic solid-on-solid model by introducing inhomogeneous energy barriers for surface diffusion. Growth on a patterned substrate promotes the spatial ordering of islands, which also leads to a narrow island size dist...

the adsorption of lead (11) and copper (11) in a fixed bed column using activated carbonprepared from nipa palm nut was investigated. thomas model and yoon and nelson kinetic models were used to analyze the column performance. the rate constant for thomas model increased with increase in flow rate and initial ion concentration but remained constant at varying bed height. adsorption capacity for...

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Detailed chemical kinetic modeling based on computational quantum chemistry has been quite successful in making quantitative predictions about some systems, particularly the combustion of small hydrocarbons and certain areas of atmospheric chemistry. The gas phase chemistry of many processes in high-temperature inorganic systems, from materials synthesis to propulsion to waste incineration, cou...