**Numerical, modeling, and theoretical aspects of scalar transport in turbulent flows**

**Speaker:** Guillaume Blanquart, California Institute of Technology

**Series:** MAE Departmental Seminars

**Location:**
COMPU104

**Date/Time: **Friday, November 15, 2013, 3:30 p.m.
- 4:30 p.m.

**Abstract:**

Passive scalars are used to represent the concentration of chemical species, small temperature changes, and particulates. They are characterized by their Schmidt number (the ratio of gas viscosity to scalar diffusivity). The interaction between convection, diffusion, and turbulent transport leads to the formation of small scale structures, which become increasingly small as the Schmidt number increases. In this presentation, I will focus on three distinct aspects of scalar transport in turbulent flows. First, I will present a new semi-Lagrangian scalar transport scheme using cubic Hermite polynomial reconstruction. This numerical scheme is specifically-designed to be bounded, have low artificial dissipation, and yet have high accuracy. Then, I will discuss current challenges in modeling forced isotropic turbulent flows, namely how to force the momentum and scalar transport equations, and how to model the sub-filter scalar flux term and sub-filter scalar variance (both in the inertial and viscous-convective subrange). Finally, I will revisit Bachelor's theory, and more specifically the predicted k^-1 scaling of the scalar energy spectrum, by analyzing the scalar structure functions through the forced version of the equation Yaglow derived in 1949.

**Biography:**

Guillaume Blanquart is an Assistant Professor in the Mechanical and Civil Engineering department at Caltech. He received his BS and his first MS in Applied Mathematics from École Polytechnique, France, in 2002. He received a second MS in Aeronautics and Astronautics in 2004 and his PhD in Mechanical Engineering in 2008, both from Stanford University. He continued as a Postdoctoral Scholar under the supervision of Professor Heinz Pitsch at Stanford University before joining Caltech in 2009. He received the NSF Career Award in 2011 and the DOE Early Career Award in 2011. His research is funded currently by the DOE, NSF, AFOSR, Boeing, and Energent.