Quadrature Method of Moments Applied to Laminar Flows
This study compares the capabilities of the conventional and quadrature methods of moments to describe condensational growth in a well known laminar flow aerosol reactor model. Governing equations for energy, lower order radial moments of the particle size distribution, and vapor transport are written for a two dimensional model using both approaches.Conventional and quadrature techniques to obtain closure of the moment equations are applied and compared. The conventional method requires certain approximations to the growth law. These include assumptions that the Kelvin effect is negligible and that the particle growth rate function is linear in particle size. In contrast, restrictive constraints of the conventional method of moments to obtain closure are avoided by applying the quadrature method. Numerical results for the laminar flow aerosol reactor model are obtained for a six moment formulation of the seed particle distribution to illustrate application of the quadrature method to continuous polydisperse distributions. We present the first calculations with the new quadrature method of moments to a two dimensional aerosol transport and growth model.
Participants:
Roger H. Rangel, Department of Mechanical and Aerospace Engineering, University of California, Irvine
Darrell A. Terry, Department of Mechanical and Aerospace Engineering, University of California, Irvine
Robert McGraw, Department of Applied Science, Brookhaven National Laboratory, Upton, New York
Publications:
- Terry, D. A.; McGraw, R.; Rangel, R. H.; 2001. Method of Moments Solutions for a Laminar Flow Reactor Model. Aerosol Science and Technology, 34 (4), 353-362.
Particle Formation Processes in Turbulent Flows
This study investigates particle formation processes in high speed, compressible turbulent flows. More specifically, we examine the competition among the nucleation and growth mechanisms in the flows using numerical models.We use a flow field model to describe velocity distributions, and mass and thermal transport properties. The chemical kinetics model is an overlay on the flow field, and includes both heterogeneous and homogeneous growth mechanisms that compete for any available condensable vapor. Coagulation is also included in the chemical kinetics model. In the kinetics model the condensed phase is described statistically using moments of the particle size distribution. Further, a light scattering model, using the moments of the size distributions, is included to provide a physically meaningful interpretation of the size distributions. Finally, results of a parametric study will be described providing insights to sensitivities on physical processes, and insights on competition between nucleation growth mechanisms in turbulent flows.
Participants:
Roger H. Rangel, Department of Mechanical and Aerospace Engineering, University of California, Irvine
Darrell A. Terry, Department of Mechanical and Aerospace Engineering, University of California, Irvine
Robert McGraw, Department of Applied Science, Brookhaven National Laboratory, Upton, New York
Publications:
- Rangel, R., Bian, X. (1998). Undercooling and Contact Resistance in Stagnation-Flow Solidification on a Semi-Infinite Substrate. Int. J. Heat Mass Transfer, 41(12), 1645-1653.
- Terry, D., Rangel, R. A Jet Exhaust Model for Soot Dispersion and Visibility. In 2005 IEEE Aerospace Conference Proceedings. Big Sky, Montana. Paper 9.0102.