Multiphase Turbulent Modeling using LES

The modeling of multiphase, turbulent flows and their dynamics has become increasingly important in many environmental, geophysical, and engineering applications. These areas require the use of models that can effectively represent both the multiphase and turbulent characteristics involved in the simulation. Due to the large increase in computational power required to both simulate multiphase and turbulent flow, new methods have been developed in an effort to make these simulations more computationally feasible. Presented here is one type of multiphase system incorporating various types of turbulent models based on large eddy simulation (LES). Multiphase flows by themselves currently constitute a major area of active research. Most of these models rely on the idea that the domain is composed of a continuum of particles. From here, the system can be represented as strictly Eulerian, mixed Eulerian-Lagrangian, or some other type of representation. The decision to go with one representation will have consequences later and should be considered carefully although usually for most systems it is obvious which viewpoint will be the better. For instance if we were modeling a bubbly flow, and the bubble size were on the order of the systems grid spacing, a mixed Eulerianlagrangian method would work best. The main difficulties lie in how to represent the additional coupling terms between each phase (e.g. phase transitions or drag) which are on the order of the number of phases being considered. The other difficulty is in the numerical discretization where each phase occupies a volumetric fraction of ech grid cell. If these phases behave with significantly different physics, i.e. water vs. gas, it may not be adequate to use the volumetric considerations to model each of the mixed cells. For simplicity in this paper we will only consider a two phase Eulerian model, however extensions to Eulerianlagrangian and multiple phase models can be found in [5]. Flows that have high enough Reynold’s numbers to be turbulent also often come up in applications. A major difficulty in modeling turbulence is the enormously disprate scales on which turbulent physics occurs. Many models attempt to capture as much physics as possible while not requiring the modeling of the entire scale range. Turbulent flow models used in practice consequently differ widely depending on the application and level of detail needed to fully