• [2013-06-14]

  Lagrangian and multi-scale investigations of turbulent flows

Speaker： Yang Yue, Ph.D. 
Time：15:00 pm
Date：June 19, 2013
Venue：Room 210, COE Building No.1
Host: Prof. Shiyi Chen 

Abstract:

The Lagrangian method for the study of turbulence is a classical but challenging approach. We present a series of Lagrangian investigations of turbulent flows with increasing complexities, from the dispersion of tracer particles to the evolution of Lagrangian material surfaces, from Lagrangian kinematics to Lagrangian vortex dynamics, and from the subgrid-scale modeling of inert turbulent mixing to the large-eddy simulation (LES) of turbulent combustion with Lagrangian particle methods. The goal is to develop novel computational and multi-scale methods for quantitative predictions of turbulent mixing and combustion. In particular, we study the non-local geometry of finite-sized Lagrangian structures in homogenous isotropic turbulence and wall-bounded turbulence. The multi-scale geometric analysis is applied on the evolution of Lagrangian fields, to extract Lagrangian structures at different length scales and to characterize their non-local geometry in a space of reduced geometrical parameters. In order to explore the connection and corresponding representations between Lagrangian kinematics and vortex dynamics, we develop a theoretical formulation and numerical methods for computation of the evolution of a vortex-surface field. In the Lagrangian framework, we apply the probability density function (PDF)approach to turbulent combustion with a LES/PDF modeling study of a non-premixed CO/H2 temporally-evolving turbulent planar jet flame. The performance of the hybrid LES/PDF methodology is assessed through detailed a posteriori comparisons with direct numerical simulation of the same flame.

Biography: 

Yue Yang received double BE degrees in Thermal Engineering and Computer Science from Zhejiang University in 2004, MS degree in fluid mechanics from Institute of Mechanics, Chinese Academy of Sciences in 2007, and PhD degree in Aeronautics from California Institute of Technology in 2011. In his PhD dissertation, advised by Prof. Dale Pullin, Yang developed a novel Lagrangian formulation and multi-scale diagnostic tools to study fluid turbulence and vortex dynamics. Yang received theRichard Bruce Chapman Memorial Award for distinguished research in Hydrodynamics from Caltech and the Combustion Energy Research Fellowship from CEFRC, Princeton University in 2011. Yang is working with Prof. Stephen Pope of Cornell University and Dr. Jacqueline Chen of Sandia National Laboratories on advanced simulations of turbulent combustion.