| Description |
The development of models for use in computational fluid dynamics often rely on a set of assumptions, as resolving the full set of length and timescales is often unfeasible in terms of computational cost for applied flow regimes. Many models rely on statistical formulations as the method for development. In large-eddy simulation, the prescription of inlet conditions affect the overall outcome of the results. Two turbulent inlet methods are implemented into computational fluid dynamics code and simulations are run to compare results to a stationary inlet for an experimental coaxial jet flow configuration. Both of the methods rely on the recreation of first- and second-order statistics the mean and variance in the derivations. A flamelet model is presented that accounts for nonequilibrium effects in combustion systems. Subgrid effects of the model are accounted for with a presumed probability density function method for mixture fraction and scalar dissipation rates. The flamelet library approach is extended from past flamelet studies to include five independent variables: extent of reaction, mixture fraction, scalar dissipation rate, scalar variance, and heat loss. For dispersed multiphase flow simulations, transporting the moments of a population balance equation can often provide good results. Moments methods rely on tracking the statistical properties of a particle size distribution. Utilizing an Eulerian moment method provides a computationally cheaper way to track particles than using a Lagrangian method. The quadrature method of moments is used for the simulation of the particle size distribution of calcium carbonate precipitation. Two sets of simulations are run, the first set uses an idealized geometry with an increasing Reynolds number, the second set of simulations uses pilot scale reactors. The mixing rates that occur in each of these simulation sets affect the outcome of the particle size distributions of the precipitate particles. The conditional quadrature method of moments is used to simulate inert particles of nonnegligible Stokes number. These larger particles require using velocities as an internal coordinate. Simple cases are set up to show the implementation of the method showing proper behavior with particle trajectory crossing and wall interaction cases. A comparison of the method with experimental results of inert particle flow for monodisperse and polydisperse particle size distributions is shown for coaxial jet flow. The method is shown to be extendable to any arbitrary number of internal coordinates, which should make it useful in modeling of complex multivariate particle systems. |
