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Juan Pablo Trelles
University of Minnesota |
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Numerical (Num, heavy-particle temperature) and experimental (Exp, optical images) results of the flow from an arc plasma torch. |
I am a post-doctoral associate working at the High Temperature and Plasma Laboratory (HTPL) in the Mechanical Engineering Department of the University of Minnesota, under the guidance of Dr. Joachim Heberlein and Dr. Emil Pfender on the modeling of thermal plasma flows.
The advancement of science constantly stresses to a higher degree the need for more robust, accurate, and efficient methods for solving even more complex transport phenomena problems. These problems encompass multiple physics, multiple scales, and different degrees of non-equilibrium. My main research goal is the theoretical and computational study of non-equilibrium and multi-scale transport phenomena. I am interested on the development of computational techniques ranging from discretization methods (particularly variational multi-scale finite element methods), to coupling strategies between heterogeneous techniques (i.e. hybrid fluid-particle methods), to parallel implicit solution methods (i.e. Newton-Krylov-Schwarz methods). My research interests involve the study of both, fundamental (e.g. flow instability, flow-surface interactions, kinetic non-equilibrium) as well as applied (e.g. materials processing, design optimization, process design and control) flow problems. In a broader context, my research comprises fields and applications in which non-equilibrium and multi-scale transport phenomena play a leading role; these range from high speed and rarefied gas flows to microfluidics and phase change processes, to flow turbulence and flow generated sound. I am also strongly interested on the development of sustainable energy systems and on the application of in the Service Learning in engineering.
Current and past projects: (for more details click on the title of the project)
Non-Equilibrium Thermal Plasmas:
Considering that the occurrence of non-equilibrium effects in thermal plasma processes is the rule rather than the exception, the need for non-equilibrium description of thermal plasmas is compelling. But, the added complexity of the equations of non-equilibrium models and of their thermodynamic and transport properties, and the subsequent significantly greater computational cost has limited the use of non-equilibrium models for the description of thermal plasma flows in realistic applications, which often involve three-dimensional and time-dependent characteristics. Although several non-equilibrium models have been applied to two-dimensional problems, and several equilibrium models have been applied to three-dimensional steady-state and time-dependent problems, non-equilibrium models applied to three-dimensional problems are scarce. Furthermore, no non-equilibrium model applied to a three-dimensional and time-dependent problem has been reported in the literature yet. In this research a non-equilibrium model based on a two-temperature four-component chemical equilibrium model of an argon plasma is developed. To understand the importance of thermal non-equilibrium in plasma – cold-flow interactions, the results from the non-equilibrium model are copared with those from a thermal equilibrium model. The non-equilibrium model is equivalent to the equilibrium model if thermal equilibrium is assumed. The results obtained with the non-equilibrium model present significant differences from those obtained with the equilibrium model, especially in the observed arc dynamics, the total voltage drops, and outlet temperatures and velocities; the results from the non-equilibrium show improved agreement with experimental observations This project has been developed at the University of Minnesota.
Thermal Plasma Flow Instabilities:
Thermal plasma flows are paramount examples of these phenomena: they involve multi-physics (fluid dynamics, reactive phenomena, electromagnetism, surface chemistry), are inherently multi-scale (due to steep property gradients and imbalances among different internal processes), and often are in different states of non-equilibrium (due to the large disparity between characteristic time scales of the plasma flow and intrinsic relaxation times of the plasma constituents, causing chemical, ionization, and thermal non-equilibrium). Furthermore, thermodynamically, electric arcs can be considered as dissipative structures. My dissertation work consists on the computational study of flow instabilities in Direct Current (DC) arc plasma torches. These torches are the key components of a number of industrial applications, ranging from plasma spraying and cutting, to toxic waste treatment and nanoparticle synthesis. The further development of these processes has been limited by our lack of fundamental understanding of the flow inside plasma torches. This canonical plasma flow is inherently unsteady, three-dimensional, strongly nonlinear, and is susceptible to different fluid-dynamic and electromagnetic instabilities. The extreme conditions inside plasma torches (i.e. temperatures above 20000 K) make numerical simulation the only alternative for its analysis. Mathematically, this flow can be described by a set of conservation equations for a reacting gas flow, fully coupled to a set of electromagnetic equations. This project is part of my Ph.D. dissertation at the University of Minnesota, working under the direction of Dr. Joachim Heberlein and Dr. Emil Pfender.
Portable Standalone Vaccine Refrigeration:
The PerUML is a Service-Learning project directed by Dr. John Duffy and aimed to improve the living conditions of people in remote Peruvian villages through the use of sustainable energies. Through it, faculty and students work in the design, fabrication, and installation of renewable energy systems in medical clinics, schools, and town halls for vaccine refrigeration, lights, radio communication, and computer use. The PerUML faced the challenge of developing a vaccine refrigerator to be used in vaccination campaigns in remote villages in the Peruvian Andes. The design of this device faces extreme energy efficiency and portability constraints, i.e. it needs to keep vaccines between 4 and 7 ° C during several days without any external source of electricity (off grid). Our design combines unique insulation materials, closed-loop thermal control, and thermal and electrical energy storage systems in a light weight, standalone, solar-powered device. This project was part of my work towards my M.Sc. degree from the University of Massachusetts Lowell, working under the direction of Dr. John Duffy.
Design of a Biogas Carburetor:
The use of renewable energies requires the development of new designs and/or the modification of current designs. This project is part of the project “Biogas para la Generacion de Energía” from the Instituto de Motores de Combustion Interna (IMCI), Department of Mechanical Engineering of the Universidad Nacional de Ingeniería (UNI) in Lima, Perú, directed by Ing. Alfredo Oliveros and Dr. Guillermo Lira. The overall goal of this project is to develop technology to modify current internal combustion engines to work with biogas. This project was part of my thesis towards the professional title of Mechanical Engineer, from the Universidad Nacional de Ingeniería working under the direction of Dr. Guillermo Lira.
Ph.D. in Mechanical Engineering (2007)
Minor in Aerospace Engineering
University of Minnesota, Minneapolis, Minnesota
M.S. in Energy Engineering (2003)
University of Massachusetts, Lowell, Massachusetts
B.S. in Mechanical Engineering (2000)
Universidad Nacional de Ingeniería, Lima, Perú
2006 Doctoral Dissertation Fellowship, University of Minnesota, Minneapolis, Minnesota
2003 Graduate Faculty in Mechanical Engineering Financial Award, University of Minnesota, Minneapolis, Minnesota
2003 Outstanding Graduate Student Award, University of Massachusetts, Lowell, Massachusetts
2001 Peruvian distinction: First-rate of Civil Service of the State, Malvas, Perú
2000 Diploma, ranked first from the class of 2000-II, Mechanical Engineering Department, Universidad Nacional de Ingeniería, Lima, Perú
1999 Diploma, ranked first from the Mechanical Engineering Department (from approx. 1500 students), Universidad Nacional de Ingeniería, Lima, Perú
1994 General Brigadier, Leoncio Prado Military School, Callao, Perú
