Research

My CV (pdf) summarizes my past work. Google Scholar Citations lists my publications. My academic publications and presentations are also archived online here. Some additional details are below.

Water jet breakup and trajectory

I am researching the breakup and trajectory of liquid jets, with a focus on fire protection applications. The overall goals of this research are to understand the factors influencing the trajectory of a water jet and predict the trajectory of a water jet. There is much experimental research on the trajectory of large water jets, but the vast majority of it is poorly characterized and does not measure anything related to the breakup of the jet. Neither does most theories, though mine does. I recently (2019) completed a rather difficult and unfortunately limited series of experiments varying the breakup length of the jet, all else (approximately) equal — results to be published.

The effect of different nozzle geometries on the breakup and trajectory of large water jets has been known for a long time. Towards understanding the influence of nozzle geometry on turbulent jet breakup, I've developed a new theoretical framework which I call conditional damped random surface velocity (CDRSV) theory. This framework is a fair bit more careful than previous simple theories. For validation of CDRSV theory I compiled a large experimental database using data from long pipes. Using a regression to relate the pipe friction factor to turbulence intensity and including rough pipes, I was able to estimate the influence of turbulence intensity on many breakup quantities. Current CDRSV theory does not adequately represent the experimental data, but the theory generally does better than previous comparable theories. After my PhD I will investigate improved CDRSV theories.

More recent work has examined improving the jet breakup regime diagram and the validation of turbulent jet breakup models.

Publications

B. Trettel and O. A. Ezekoye, "Theoretical range and trajectory of a water jet", in Proceedings of ASME 2015 International Mechanical Engineering Congress and Exposition, Houston, TX, 2015. DOI: 10.1115/IMECE2015-52103. (Currently being rewritten, updated, corrected, and improved for publication in a journal.)

B. Trettel, "Conditional damped random surface velocity model of turbulent jet breakup". ICLASS 2018, Chicago, IL, 2018. Preprint DOI: 10.31224/osf.io/35u7g.

B. Trettel, "Estimating turbulent kinetic energy and dissipation from internal flow loss coefficients". ICLASS 2018, Chicago, IL, 2018. Preprint DOI: 10.31224/osf.io/qsfp7.

B. Trettel, "Turbulent theory of velocity-profile-induced jet breakup". ILASS-Americas 2019, Tempe, AZ, 2019. Preprint DOI: 10.31224/osf.io/486jh.

B. Trettel, "Improving the validation of turbulent jet breakup models". ILASS-Americas 2019, Tempe, AZ, 2019. Preprint DOI: 10.31224/osf.io/k2fnm.

B. Trettel, "Reevaluating the jet breakup regime diagram". To be submitted to Atomization and Sprays, 2020. Preprint DOI: 10.31224/osf.io/nqhs5.

Past research

Outflow boundary conditions for buoyancy-driven flows

For my Master's research at UMD, I tested different types of outflow boundary conditions for buoyancy-driven flows. Tim Colonius notes that open boundary conditions present "an open and substantial modeling problem that is no less challenging, and arguably no less important, than subgrid modeling for turbulence." Thus, I explored several different approaches and compared their successes and failures. My Master's thesis is available online. This work was not particularly good, but I was learning at the time. I believe the literature review is the most useful part of this work. Today (2019) I remain interested in improved boundary conditions and am considering returning to this area after my PhD.

Publication

B. Trettel, "Outflow boundary conditions for low-Mach buoyant computational fluid dynamics," MS thesis, University of Maryland, College Park, 2013. URL: http://hdl.handle.net/1903/14700