Department of Aerospace Engineering

Computational Fluid Dynamics Center Seminar Series: Damien Kah, CBE Department, "An Eulerian model for the dynamics of polydisperse evaporating Sprays: Combining the multi fluid model with the quadrature method of moments"

 

This CFD Center seminar will be held on Tuesday, October 14, 2008, at 4:10 PM in Room 1235 Howe Hall.

Damien Kah
Visiting Student under the supervision of Dr. Fox
CBE Department - Iowa State University

An Eulerian model for the dynamics of polydisperse evaporating Sprays: Combining the multi fluid model with the quadrature method of moments

Dilute gas-particle flows can be described by a kinetic equation containing terms for spatial transport, gravity, fluid drag, and particle-particle collisions. However, the direct numerical solution of the kinetic equation is intractable for most applications due to large number of independent variables. A useful alternative is to reformulate the problem in terms of the moments of the number distribution function.  In this work, we are interested in size and velocity moments. In the first case, the goal is to describe a polydisperse flow. We go beyond the sectional multi fluid approach by tracking four size moments which proves to give much more accurate results. In the second case, our aim is to deal with flows far from the equilibrium (Maxwellian) limit. The challenge in both cases is the closure of the moment equations. The size distribution function is reconstructed maximizing the Shannon entropy of the system. For the velocity moments. A quadrature-based third order moment closure is derived that can be applied to gas-particle flows at any Knudsen number.  The fluxes in both spaces are treated using a kinetic description. Eventually, a coupling of the two models described before will be provided, allowing description of polydispersion, as well as droplet crossings among same size particles, in an Eulerian framework. While developed here for dilute gas-particle flows, quadrature-based moment methods can, in principle be applied to any application that can be modeled by a kinetic equation.

Biography

– Graduated from Ecole Centrale Paris (France). Major in Energetics

– PhD student in Ecole Centrale Paris and Institut Francais du Petrole (French oil Institute).

The aim of the PhD is to develop a code which simulates polydispersion (i.e. sizedistribution) of a fuel flow in an internal combustion engine, in an Eulerian framework.

Problematics:

– sprays,

– polydispersion,

– non equilibrium flow

– internal combustion engine

– In Iowa State for a semester as an exchange scholar. I work with Dr. Fox on the issue of

quadrature method of moment for non equilibrium flow.

 

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