The Harvey Rosten Award – 2025 Winner

The Harvey Rosten Award, sponsored by Siemens Digital Industries Software, recognises outstanding research in electronics cooling and thermal management. Established in memory of Harvey Rosten, a founder of Flomerics and instrumental in the development of the Simcenter Flotherm software, the award celebrates not only technical excellence, but also the curiosity, creativity, and engineering insight that continue to drive innovation in the field. In this series, we speak with past winners about their research, the ideas behind it, and the personal experiences that shaped their journey into electronics thermal engineering. The award has been running since 1997.

2025 Winner

The most recent award was granted for this publication:

Comparison of 3D manifold architectures for cooling of internal heatsinks using external airflow

G. Farrell¹, R. Nimmagadda¹, S. N. Joshi², D. J. Lohan², E. M. Dede², T. Persoons^1
1School of Engineering, Trinity College Dublin, Dublin, Ireland
²Toyota Research Institute of North America (TRINA), Ann Arbor, Michigan, USA

2025 24th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm) DOI: 10.1109/ITherm55376.2025.11235714

An Interview with…

The corresponding author for the winning publication was Gearóid Farrell, a PhD Student affiliated with Tim Persoons’ Thermal Fluids Lab (https://timpersoons.org/) at Trinity College Dublin.

Here I ask him some questions about his paper, his research journey, and the ideas and experiences that have shaped his interest in electronics thermal management…

What first sparked your interest in electronics thermal management, or brought you into the field?

I was first introduced to the field when I joined my supervisor Tim Persoons’ research group in Trinity College Dublin as a Research Assistant. I was tasked with studying novel heatsink designs as part of a collaboration with Toyota Research Institute of North America (TRINA). Although I found heat transfer modules quite challenging during my undergraduate studies, I really enjoyed the more applied nature of thermal management research. I had always loved Computational Fluid Dynamics (CFD) and numerical methods at university, so it was exciting to apply those skills to developing real-world thermal management solutions.

Your Harvey Rosten Award recognised your work on 3D manifold architectures for cooling of internal heatsinks using external airflow. Could you briefly describe what you were exploring, and what you found most interesting about it?

The work explored novel manifold heatsinks designed to use external airflow as a coolant, even in environments where the air may contain debris or contaminants. Our approach was to develop a manifold geometry that could redirect external airflow through a protected internal heatsink without creating a large obstruction to the outer flow.

What I found most interesting was using fluid mechanics principles to control the airflow paths through the heatsink. Unlike standard manifold designs, where all fluid passes through the internal structure, our CONDIV design used a multi-path approach: part of the flow passed through the internal heatsink while the remainder bypassed it externally. To achieve this, we designed the manifold to create pressure differences through local acceleration and deceleration of the flow, ultimately leading to the converging-diverging manifold concept presented in our paper.

Was there a particular moment during that work where things suddenly clicked, or surprised you?

There was definitely a moment where things suddenly clicked. While we already had a good idea of the overall heatsink structure, we were still struggling to generate the required pressure differential efficiently. Many of the early manifold designs had significant drawbacks. One day, while doodling random manifold fin arrangements as simulations were running, I came up with the converging-diverging concept. After running some quick 2D simulations, it immediately appeared to solve all of the issues associated with the earlier designs and eventually became the basis of the manifold presented in our paper.

Is there anything about electronics cooling that you think is often misunderstood, or perhaps oversimplified?

As a second-year PhD student, I’m probably not the best person to answer this, but one thing that stood out to me was how turbulence and transition are sometimes simplified in numerical studies, particularly at lower Reynolds numbers. In our work, we found that transitional effects in the boundary layer could strongly influence whether convection along heatsink fins remained laminar or became turbulent. Because of this, we found it important to compare standard turbulence models with models that account for transition effects, such as the Transition SST model.

Are there any developments or trends in electronics cooling that you’re particularly interested in at the moment?

Although it’s not the area I currently work in, I find topology optimisation extremely interesting for thermal management applications. I would love to explore this technique at some point in my future work – but might have to wait for it to become a bit more accessible for ANSYS Fluent users!

For someone starting out in this field, what would you suggest they focus on, or stay curious about?

For me, the fundamental physics has always been the most interesting part. When using commercial CFD software, it can be easy to overlook the physics and numerical methods happening behind the user interface. I think developing a strong understanding of the fundamentals not only improves your technical skills but also helps maintain curiosity and motivation.

Has anything outside of engineering, perhaps a hobby or interest, shaped how you think about your work?

Outside engineering, I’ve always enjoyed painting and sketching. While it hasn’t directly influenced the technical side of my work, it has definitely made me focus a lot more on presenting results in a clear and visually appealing way, particularly when creating schematics and diagrams. I think this helps to communicate the results of my work, and hopefully makes the papers more enjoyable to read.

Is there anything I didn’t ask that you wish I had, and what would have been your answer?

I think it’s interesting to ask people how they first became interested in engineering. During secondary school in Ireland, I had very little understanding of engineering careers outside of building services. A few months before finalising my university course choices, I became obsessed with YouTube videos explaining engineering principles and how engineers design everything from coffee machines to jet engines. That helped me realise there were careers where I could apply my interest in science in a practical way, and it ultimately set me on the path I’m on today.

Thank you Gearóid for your answers!

The Harvey Rosten Award Committee

The committee convenes annually and considers over 40 publications from the previous year that conform to the specific requirements of: context, pragmatism, innovation, broad applicability and accessibility. A long list is identified, whereupon a more rigorous selection criteria is applied to determine a shortlist, from which the committee subsequently identifies a winner via a democratic ballot.

The committee comprises:

• Robin Bornoff – Chair
• Jim Wilson
• Cathy Biber
• Ross Wilcoxon
• John Parry