Before I was a scientist I was an artist. Okay, maybe that’s going a little far, but as a child I loved to draw. I always had a pencil in my hand, drawing racing motorcycles, horses, and everything else that was on the move (hint: The constructal law started then). Seeing something in these designs, my parents sent me to art classes after school. In my office at Duke, I still have a drawing of two Dutch ships I made in the fourth grade—and a portrait of my younger daughter, Teresa, I drew in a restaurant in Rome in 1990.
In retrospect, I realize that I had the feeling that I “saw” how things moved and how they fit together. Drawings provide the first clue about operation; they begin to tell us what something is by suggesting what it does. As Michelangelo reportedly observed five centuries ago, “Design (drawing)…is the root of all sciences.” I am always offering my amateur sketches to my students at Duke so they can see what we’re talking about, to remind them that the physical world is not made up of ivory-tower abstractions but images with shape and structure that move across the landscape and conform to physical laws.
Where a drawing provides the outline of an object, science allows us to burrow in and see how it functions—drawings show us the parts; science shows us how they move. Science is effective because it is concise. It converts physical phenomena into statements, formulas, and mathematical equations that have great explanatory power. In the process, it also tends to sever objects from their natural state. The mighty Danube ferrying water from central Europe or an elegant antelope jumping across the savanna loses its essential character when translated into data.
Speaking practically, this wouldn’t matter if design were simply an aesthetic concern. Science goes with what works, pleasantries be damned! The rendering of nature as charts, tables of numbers, graphs, and equations has opened up vast areas of knowledge and understanding. It underpins much of my work. However, it has also blinded us to deeper truths. Like the muck-raker in John Bunyan’s classic novel The Pilgrim’s Progress, it has focused the researcher’s gaze downward on his own small patch of ground.
When we raise our eyes and look around, we encounter a wondrous world of living drawings: birds and airplanes painted against an azure sky, pine trees and skyscrapers reaching for the heavens, rivers and roads snaking across the Earth’s surface. If we take a closer and wider look at the same time, we also see how much these images have in common: similarities in shape and structure so numerous that they can’t be the result of accident.
The constructal law makes “design” a concept in science. It reveals that scientists have been digging in the wrong patch when they ignored configuration or simply took it for granted. Design is, in fact, a spontaneously arising and evolving phenomenon in nature. Design happens all the time everywhere, not as the result of one mechanism but as the expression of a law of physics like Galileo’s principle of gravitational fall and the laws of thermodynamics.
Language can make this hard to grasp. The constructal law uses “design” as a noun that describes a configuration, which is known by many other names: image, pattern, rhythm, drawing, motif, etc. This sense, however, has been conflated with the verb “to design” that refers to the power of the human brain to contrive and to project images and linkages to new, higher planes. To design is human. It is human to absorb images that invade us, to reflect upon them in our minds, and to use them as personal catapults to make our drawings and devices so that we become a better and better species moving more easily on the landscape. In fact, we are so tied to the technologies that enhance our movement that we have evolved into a human-and-machine species (more on this later).
The verb “to design” has been monumentally unproductive in our quest to understand design in nature for three main reasons. First, it led to the common view that the things humans design are “artificial,” in contrast to the “natural” designs that surround us. This is wrong, because we are part of nature and our designs are governed by the same principle as everything else, the constructal law. Second, it has led some of us to search for “the designer”—God, or an individual, who must be behind every design. Science is not and never was the search for “the designer.” The name for that much older search is religion. Finally, it has led other, more scientifically minded people to reject the idea of design in nature as part of a broader repudiation of the traditional idea of a designer.
The constructal law tells us to stop looking for a phantom designer—there is no single mechanism or design-generating entity that can be found in river basins, blood vessels, transportation systems, etc. It teaches us, instead, that design is a phenomenon that emerges naturally as patterns. It also tells us that this evolving shape and structure is predictable. That is, if we know what is moving through a flow system, we can predict the sequence of designs that will emerge and evolve to facilitate the currents that run through it.
This starts with a drawing, or to use a better metaphor, the first frame of a movie—with what something looks like at a given moment. But nature does not exist in freeze-frame; it is dynamic, ever evolving. As the film rolls, the drawing changes over time in one direction: to flow more easily. I’m tempted to give this never-ending movie a grand and catchy title like Gone with the Flow or I, Constructal. This thrilling blockbuster details how flow systems configure and reconfigure themselves to overcome the friction and other forms of resistance that hinder them. Faster, easier, cheaper in terms of fuel (useful energy, exergy) used and materials required for movement: that is the flow system’s mantra.
In this chapter we show that evolving design in accordance with the constructal law is a universal phenomenon by focusing on three flow systems that would seem to have little in common. The first comprises the man-made cooling systems designed to remove heat from electronic devices. The second is the river basin that represents inanimate, nonbiological systems. The third is the system of blood vessels that carry oxygen and energy throughout our bodies. Each of these systems has been explored in great depth through the years; we know a tremendous amount about their shape and structure. But the systems have also been studied in isolation. This approach has led researchers to consider them not just apples and oranges, but apples and sports cars, oranges and shoes. The constructal law reveals that these flow systems generate strikingly similar designs in order to facilitate their own movement.
All three examples have at least two things in common. First, they are steady-state systems, that is, the currents that run through them (heat, water, blood) do not change much. Second, all three systems face one of the most common challenges in nature: how to move currents (of heat, fluid, people, goods, it doesn’t matter) from a point to an area or from an area to a point. This may sound like an abstract idea, but it is one that affects all of us every day. The movement of water from the reservoir (a point) to the various faucets and taps throughout our community (the area) is one example. So is the movement of sewage from each home and business (the area) to the treatment plant (a point). When we leave our homes each morning to go to work or the mall or to take the kids to school we become part of the volume of people flowing from the area (our neighborhoods) to various points within our local communities. We travel along networks of roads designed to get us where we want to go in the most efficient manner: faster, easier, cheaper. When we zoom along to our destination, obstacles have been mitigated if not eliminated. When we are stuck in traffic because of bottlenecks, we pay the price for outdated design.
I faced an area-to-point problem earlier in my career when I was designing cooling systems for electronics. My objective was to install as much circuitry as possible into the fixed space of a machine. Like everything else that moves, electronic components generate heat as they function. The heat is the result of dissipating (destroying) in the electrical resistances of the circuitry the electrical work taken from the wall outlet, in order to push all the electric currents through the circuitry. The more electronics you squeeze into a confined space, the hotter it gets.
The modern world of multifunctional cell phones and laptop computers hundreds of times more powerful than the room-size units that represented cutting-edge technology during the 1950s would not be possible if engineers hadn’t figured out how to channel away the heat, making these devices smaller, cheaper, and faster all at once. The burgeoning era of nanotechnology—which promises machines smaller than an eyelash—depends in great part on our ability to make those tiny workhorses operate without melting. Most people don’t give it much thought, but countless things we take for granted depend on our ability to remove heat.
There are many ways to cool a system. You can blow air on it, as a fan does inside your personal computer, or you can run coolant through it, as the tubes of Freon in many refrigerators and air conditioners do. Both approaches are effective, but they involve various costs—just as there’s no free lunch, there’s no free cooling. Blowers and cooling tubes take up lots of space. This doesn’t matter much with large appliances. But when we are measuring things in micrometers (a millionth of a meter), we need a better way.
My challenge while doing theoretical research in the early 1990s was to find a way to cool a solid block of circuits so small that it had no space for coolant coils or air. I had to find a way to cool, without a moving fluid, the inside of an electronic rock that was constantly generating intense heat.
~~Design In Nature : How The Constructal Law Governs Evolution In Biology, Physics, Technology, and Social Organization -by- Adrian Bejan and J. Peder Zane
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