Date of Award
2026
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Mechanical and Aerospace Engineering
Committee Chair
Babak Shotorban
Committee Member
Jason Cassibry
Committee Member
Natalie Click
Committee Member
Robert Frederick
Committee Member
Kader Frendi
Research Advisor
Babak Shotorban
Subject(s)
Turbulence--Mathematical models, Eddies--Mathematical models, Flame spread--Mathematical models
Abstract
To improve the understanding of the role of firebrands in fire spread, the dispersion and deposition of firebrands carried by turbulent jet flows were simulated by Lagrangian particle tracking and large--eddy simulation. The simulations were configured to replicate previous experiments involving cubiform and cylindrical particles carried by pipe flow and the resulting jet flow before deposition on the ground. First, validations were performed for the jet flow simulations by comparing quantities such as the jet spread rate and velocity decay constant with previous experimental and theoretical values for free jet flows. Then, two series of simulations were performed to evaluate firebrand motion and deposition. In the first series, the motion of firebrands in the pipe was neglected, and they were released at the pipe exit with the focus of the study on particle motion in the jet region. Quantitative analysis using particle time constants and terminal velocities indicated that large--scale turbulence had a dominant effect on the trajectories of the firebrands for the firebrand mass and size considered in this study. Both drag and gravitational forces were found to be important for particle motion. Drag reversal occurred as the firebrands decelerated outside the jet core. Probability distributions of the coordinates of the deposited particles were computed using high--resolution kernel density estimation and compared with previous experimental data. The simulations reproduced experimental deposition means within ten percent. Including rotational motion in the cylindrical particle model improved cross--stream motion and deposition predictions. In the second series, particles were released and carried in the pipe, and then in the jet region before deposition. Internal--pipe initialization of particles further improved streamwise deposition agreement with experimental results, compared with the first scenario, but exposed deficiencies in particle--surface modeling.
Recommended Citation
Damiani, Patrick Wayne, "A computational investigation of the deposition of firebrands subject to a turbulent jet flow" (2026). Dissertations. 478.
https://louis.uah.edu/uah-dissertations/478