Adrian Bejan | Rivers of heat, serendipity, innovation, from Design in Nature

In this video, Adrian Bejan introduces the concept of rivers of heat, a continuation of earlier flow models involving pedestrian flow and rivers of water. Now, the focus shifts to heat flowing through a rectangular slab, a system driven by heat generation per unit volume and shaped by a high-conductivity blade. Bejan presents the architecture as a sequence of cooling elements, each contributing to a larger system. Through this model, he explains how innovations emerge from understanding invisible flows and making decisions based on architecture, conductivity, and volume. Along the way, Bejan introduces the idea of serendipity, revealing how discovery happens unexpectedly through attention to design and flow.

• Bejan presents a rectangular slab with a high-conductivity blade and internal heat generation, illustrating how heat escapes through the blade, much like water flows downhill from hillsides into a river.

• The system evolves into multiple cooling elements, stacked and configured to create a larger structure, each delivering its heat current and contributing to the total flow.

• The heat flow per unit area increases as the system size decreases, showing that miniaturization leads to more effective designs and more performance packed into a smaller space.

• Bejan compares heat flow to knowledge, explaining that both transfer from high to low temperatures. This is a natural tendency linked to the second law of thermodynamics and irreversibility.

• Bejan concludes with the idea that innovation is not a one-time event but a continuous process, driven by the architecture of flow and supported by the investments, both mental and material, made along the way.

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Umit Gunes, Ph.D.
Assoc. Prof.​ |​ Yildiz Technical University
Editor​ | International Communications in Heat and Mass Transfer
Guest Editor​ |​ Philosophical Transactions of the Royal Society A
Guest Editor​ |​ BioSystems
​Web | umitgunes.com