The Development of a Dissipation Transport Equation and its Application to Particle Laden Turbulent Channel Flows

 Date: Tuesday, March 24, 2009
Time: 10:00am - 11:00am
Location: LBNL bldg. 50A, Room 5132

Speaker:
John Schwarzkopf
Washington State University

Abstract:
Particle laden turbulent flows are commonly found in combustion,
atmospheric flows and industrial applications. This presentation
will focus on the development of a volume averaged dissipation
equation to aid in modeling the carrier phase turbulence in particle
laden flows. By volume averaging, an additional production of
dissipation term due to particle surfaces is identified. During the
development, it was assumed that each coefficient was the sum of the
coefficient for single phase flow and a coefficient quantifying the
contribution of the particulate phase. The coefficient for the new
production of dissipation term (due to the presence of particles)
was found from experimental data related to homogeneous turbulence
generated by particles, and the coefficient for the dissipation of
dissipation term was determined from homogeneous, isotropic
turbulent decay with stationary particles using DNS. To assess the
effects of the dissipation equation, a numerical model was developed
and applied to particles falling in a channel of downward turbulent
air flow. Boundary conditions were also developed to ensure that the
production of turbulent kinetic energy due to mean velocity
gradients and particle surfaces balanced with the turbulent
dissipation near the wall. The coefficients associated with the
production of dissipation terms were varied to understand the role
of the particle dissipation on the carrier phase turbulent kinetic
energy across the channel. The results show that the model
predictions compare reasonably well with the experimental data and
that the dissipation coefficients play a critical role in predicting
the turbulent kinetic energy in particle laden turbulent flows.

Host of Seminar:

    John Bell