PAPER BY UTSI PROFESSOR & FORMER STUDENT OFFERS BETTER THERMAL SIMULATION METHODS

A more efficient way of simulating the cooling of electronic packages is advocated in a recently published technical paper written by a University of Tennessee Space Institute professor and one of his former undergraduate students.

“Our paper illustrates a successful endeavor of working with undergraduates,” said Dr. Joe Majdalani, now UTSI’s Jack D. Whitfield Professor of High Speed Flows.

The International Journal of Heat and Mass Transfer immediately accepted the paper – without the usual lengthy judging process – and published it earlier this year. Dr. W. J. Minkowycz, professor of mechanical engineering and editor of the Journal, praised the paper. In a letter to Majdalani, the editor wrote: “I have reviewed the paper carefully and find it to be of good quality. Indeed the quality standard of the paper merits its acceptance for publication without further review.”

Co-author Kyle A. Brucker, now at the University of California in San Diego, was an undergraduate student of Majdalani’s at Marquette University before the professor joined the Space Institute. Title of the paper is “Effective Thermal Conductivity of Common Geometric Shapes.”

The authors explore the porous block model based on replacing a “heat sink,” or heat removal device, with a volume of air – a technique that helps to simplify the simulation process, according to Majdalani.

“Our proposal – in which the volume of fluid replaces the actual heat sink – helps to model heat sinks in a way that greatly simplifies the procedure,” he added. “For instance, our approach reduces CPU (Central Processing Unit) usage by a factor of 10 to 50.”

Citing “a growing interest” in thermal management of electronic packages, Majdalani said the Accreditation Board for Engineering and Technology (ABET) requires a thermal design project from all undergraduate institutions. A text publisher has recently moved the chapter on this subject from Chapter 14 to the fourth chapter, so that students are exposed to the topic early, Majdalani said.

This enables students to apply these tools to their thermal design projects. These include the simple solutions published by Brucker and Majdalani.

“This (heat transfer in electronic packages) is becoming a key research area,” the professor said.

At Marquette, supported by Cisco and Motorola, Majdalani says, “We engaged in helping companies model heat sinks.”

In the recently published paper, Majdalani says, “We show that analytical technology can solve very complicated equations. We show how to test the strength and breadth of perturbation methods (one of his graduate courses at UTSI) by tackling a large number of complex equations.”

“My experience working with undergraduates has been an excellent one,” Majdalani said. “The success of this particular endeavor is one such example. I have learned that an undergraduate student with the proper attitude toward research can outperform a supercilious graduate who lacks maturity, accountability, or who displays emotional instability.

“In order for a graduate or undergraduate student to be successful, he or she must have a good attitude. I tell students, ‘If you have a good attitude toward research, you can get wherever you want to be.’ Kyle is a good example. He received the prestigious National Defense Science and Engineering Graduate Fellowship.”

Simple “closed form solutions such as is advocated in our paper make for ideal classroom problems,” Majdalani said.

“The explicit solutions that we provide are not limited to the rectangular porous block models used in former studies,” the professor explained. “Rather, we extend the analysis to cover most fundamental body shapes and flow configurations under both free and forced convection modes. The exact or approximate formulations that we provide apply to most common Nusselt number correlations and eliminate the need for guesswork.”

Analytical methods offered in the paper “allowed us to solve 38 free and 24 forced convection equations,” the professor said.

Majdalani thinks the findings listed in the paper “increase our repertoire of engineering approximations, both in industry and academe, especially those devoted to heat transfer processes.”