Patrick Pisciuneri

University of Pittsburgh

Mechanical Engineering, PhD•  December 2008 - August 2013

A new computational methodology is developed for large eddy simulation (LES) with the filtered density function (FDF) formulation of turbulent reacting flows. This methodology is termed the "irregularly portioned Lagrangian Monte Carlo finite difference" (IPLMCFD). It takes advantage of modern parallel platforms and mitigates the computational cost of LES/FDF significantly. The embedded algorithm addresses the load balancing issue by decomposing the computational domain into a series of irregularly shaped and sized subdomains. The resulting algorithm scales to thousands of processors with an excellent efficiency. Thus it is well suited for LES of reacting flows in large computational domains and under complex chemical kinetics. The efficiency of the IPLMCFD; and the realizability, consistency and the predictive capability of FDF are demonstrated by LES of several turbulent flames. http://d-scholarship.pitt.edu/id/eprint/19284

University of Pittsburgh

Mechanical Engineering, MS•  July 2006 - December 2008

Large eddy simulation (LES) is conducted of a turbulent piloted nonpremixed methane jet flame. This flame has been studied experimentally at Sandia National Laboratories. The subgrid scale (SGS) closure in LES is based on the scalar filtered mass density function (SFMDF) methodology. The SFMDF is essentially the mass weighted probability density function (PDF) of the SGS scalar quantities. The SFMDF is obtained from an exact transport equation which provides a closed form for the chemical reaction effects. The unclosed terms in this equation are modeled by a set of stochastic differential equations (SDEs). The SDEs are solved by a hybrid finite-difference/Lagrangian Monte Carlo procedure. This flame exhibits little local extinction. In previous work, the instantaneous flame composition was related to the mixture fraction based on the flamelet model at low strain rates. In the present work, this assumption is relaxed, and a direct solver is employed for finite-rate chemistry. The results via this method agree favorably with those obtained experimentally. The end result is an accurate and affordable method for the LES of realistic turbulent flames. http://d-scholarship.pitt.edu/id/eprint/9659