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Issue: Volume: 32 Issue: 10 (Oct. 2009)

Reconstructing Nature


By: Kenneth Wong
Stumped by a design problem? Running out of ideas? You might want to watch a grasshopper or mentally dissect a fern. That’s what the growing crop of biomimicry practitioners would encourage you to do.

To borrow the words of Ask Nature (www.asknature.org), an open-source biomimicry portal, the new field is “where biology and design cross-pollinate, so bio-inspired breakthroughs can be born.” A casual glance at the list of projects archived online at Ask Nature reveals colored fibers and fabric inspired by the wing scales of Morpho butterflies (Morphotex from Teijin Fibers in Japan), a metropolitan high-rise inspired by the skeleton structure of a sponge (the Gherkin in London), and a soil-moving system inspired by the skin of earthworms (University of Jilin in China).


Anderson Anderson Architecture used Autodesk Revit to model the green pavilion dubbed Texas Prairie Hopper. The 3D model allowed the architects to study the movement of the panels and more.
 
 

Confronted by the limitations and unfortunate consequences of industrialization, many academics, researchers, designers, and architects now turn to nature for clues on developing more sustainable inventions and creations. In this article, we follow in the tracks of a prairie hopper, translate an ageless equation, and magnify our cell structures to learn how biomimicry works. A crucial part of copying nature, as it turns out, is digitally reconstructing and simulating the natural objects’ and organisms’ behaviors using 3D modeling and analysis software.

Green Education from an Insect
Sometime in mid-May, a giant prairie hopper measuring roughly 8x40x9 feet and weighing roughly 9.3 tons (18,600 pounds) began making its way toward the Colonial Country Club in Fort Worth, Texas. The insect traveled not by hopping on its hind legs, but by way of a shipping container. Upon arrival, it was expected to strut its limbs, spread its wings, and perch by the hillside near the No. 6 fairway, where the media and guests of the Crowne Plaza Invitational PGA Tournament had assembled for a glimpse of the oversize bug.

In architecture lingo, the prairie hopper is a portable, prefabricated, modular structure. It can be segmented into individual components, transported to a site in compact form, and reassembled there. Designed as an entertainment pavilion, the two-story installation lets people drink in not just the refreshments from the bar, but also a commanding view of the nearby groves.

Though its primary color is white, the prairie hopper is a green spirit, an example of the latest innovations in sustainable architecture. Standing on a skeleton of recycled steel, the habitable hopper is covered in a mass of thermal- and evaporation-resistant limestone-composite materials. It’s off-grid, capable of heating and cooling itself via wind turbines and photovoltaic panels. The structure relies on solar-thermal collectors for potable, sanitary hot water. Depending on the sun angle of the locale and the preferred orientation of the installation, the hopper’s adjustable screens can be articulated to provide optimal shading. Behind the stairs leading to the upper deck, beds of cacti, muhlies, blue gramas, sand bluestems, and yarrows thrive without regular irrigation.


An example of the physical manifestation of the golden ratio, also known as phi, can be seen in the coil of this fern.
The prairie hopper was brought to life—merely 55 days after the idea hatched as a napkin sketch—with the expertise, labor, and support of Anderson Anderson Architecture, Texas Christian University’s Institute for Environmental Studies, Advantage Steel Service, NextEra Energy, Veristeel, and several other individuals and organizations.

A Bug’s Life
The pavilion was dubbed Texas Prairie Hopper, partly because the collapsible, ground-hugging structure with steel hinges resembles a grasshopper, and also because the modular setup allows it to hop (in a manner of speaking) from one site to the next. But once that became the official name, the project began to take on more and more grasshopper-like characteristics, according to its creators.

By the time Anderson Anderson Architecture accepted Texas Christian University’s invitation to get involved, the Crowne Plaza Invitational was merely two months away. So the team had to find creative ways to shorten the production cycle. Here, they found that the modular assembly worked in their favor.

“We used one T-shaped structure repeatedly, because [the steel fabricator, Advantage Steel Service] was able to produce it easily by ripping apart a standard I-beam,” recalls Karl Vavrek, a project manager at the architecture firm. “We reused it [as a base component] as often as possible for simplicity and consistency in the design. We only changed it when we needed to.”

Anderson Anderson Architecture decided to model the entire project in Auto­desk Revit Architecture, a 3D building information modeling (BIM) software package. “We modeled [the prairie hopper] digitally in extreme detail, essentially every single bolt, partly to speed up the steel fabrication process,” explains Mark Anderson, a founding principal of the firm. He notes that as Vavrek and Yevgeniy Ossipov, another project manager, finished designing one piece, they would send the drawings over to the steel fabricator to manufacture it. So, essentially, they were building the digital model and the real construction components simultaneously.

“We modeled the pieces in the order in which they would be built,” says Ossipov. “The first module we modeled was the frame [the system frame used by Veristeel for modular structures]. Then we made the large panels and the rails that would be attached to the frame.”

Each steel beam was cut with a series of holes. At the time of installation, the frames, rails, and panels were meant to be joined together with bungee cords, bolts, and 1500 tiny S-shaped hooks made of UV-resistant material (polyether sulphone, or PES). The advantage of digitally modeling these components in detail, Ossipov notes, was the ability to study the intersecting points and the articulated panels to ensure there were no collisions.

Because the golf tournament was going to take place during hot weather, the group realized it needed lots of shade as well as lots of surface areas for the green roof system and for showing off the native plants. 

“From the beginning, we knew we wanted the panels to be attachable at various angles, depending on the orientation of the installation or the time of day,” notes Vavrek. With Revit’s sun-angle study tools, the team was able to determine the appropriate position of each panel.

“Even though there were several of us working on the same project, we were using a single digital model,” says Vavrek. “So we had good control over the process.”

In the middle of the project, Texas Christian University’s Institute for Environmental Studies requested a photorealistic rendering of the installation, to be published in its media kit. With the Revit 3D model readily available, Ossipov was able to export the geometry of the prairie hopper as a 3D DWG file to McNeel’s Rhino software, then use Next Limit Technologies’ Maxwell Render plug-in for Rhino to produce a series of images. The results can still be seen in the institute’s online project page at www.ensc.tcu.edu/colonial.php.

An Enigmatic Fan

Many mathematicians believe physical manifestations of phi, also called the “golden ratio” or “divine ratio,” could be detected all around us, in the looping circles that form a conch shell, to the cyclical patterns of the galaxies. (Robert Langdon, the hero in Dan Brown’s The Da Vinci Code, insists it could also be found in the pyramids of Giza, the Parthenon at Athens, and Beethoven’s Fifth Symphony, among other places.) You also would find this equation in the propulsion systems and thermodynamic technologies developed by PAX Scientific, a California-based research and development corporation. Many of its patents involve adaptations of phi’s equilibrium principle to industrial processes.


PAX Scientific applies the divine ratio equation in the propulsion systems and thermodynamic technologies it develops. Here, the meshed model of the fan blades allows PaxFan (a licensee of PAX Scientific) to further study the airflow patterns it produces.
At PaxFan, a master licensee of PAX Scientific, phi turns into something cool—quite literally. “Fans made using PAX Scientific technology are quieter and use less energy per flow unit than competitive products,” declares the company. “PAX fans produce these benefits by reducing the amount of turbulence in the air before and after contact with the fan. The curved blades generate a laminar, vortical flow on their downstream side, moving air centripetally and with markedly reduced turbulence.”

“A tornado shows you an example of how nature uses phi to equalize pressure using the vortical pattern,” says Kim Penney, senior design engineer at PAX Scientific. After all, a fan is for producing airflow, so we’re looking at optimizing [the fan blades’] shape to produce that effect.”

PaxFan uses SolidWorks, a 3D mechanical design program, to digitally model its fan blades. But more importantly, PaxFan uses high-end fluid-flow and airflow simulation programs—Ansys’ Fluent and AcuSim’s AcuSolve and AcuConsole—to study the flow patterns using digital mock-ups.

“You can put your hands in front of the fan to feel its effect, but you can’t really see what’s going on with airflow patterns,” says Penney. With Fluent and AcuSim software, designers at PaxFan can subdivide the 3D model of the blades into meshes (known as “meshing” in the field of computer-based analysis and simulation), apply forces as numeric values, and then study the effects on the air around the geometry as color-coded patterns. Parasolid serves as the intermediary file format between the design program SolidWorks and the fluid and flow analysis programs used by PaxFan.

Fluent offers the SolidWorks Connection module, which gives users the ability to perform initial computational fluid analysis. The concept of the SolidWorks Connection is to identify and resolve technical nuances as the geometry model is being created, according to Ansys.

SolidWorks includes a finite-element analysis feature (previously known as CosmosWorks but now simply known as SolidWorks Simulation), which is useful for studying, for instance, the anticipated deformation of the fan blades when they come in contact with a force. SolidWorks also includes SolidWorks Flow Simulation, a set of tools for studying fluid flow and thermal analysis. Penney points out that the software’s flow simulation features would be sufficient for initial tests, but for a more comprehensive study, PaxFan needed Fluent and AcuSim.

“The density of the meshes in the fan blades themselves isn’t as important as the mesh density of the objects around the fan,” Penney advises. “That’s especially true when a fan is housed within some type of chamber. You need to be able to see how many components you can fit in between the blade tips and the nearby structure [without compromising the airflow].”

The PaxFan product line is a set of technologies available for licensing, to be incorporated into electrical appliances, refrigeration units, and HVAC (heating, ventilation, and air-conditioning) products.

“Looking to nature for engineering answers was something ancient philosophers and thinkers did, da Vinci among them, but they didn’t have the computational tools to test out their theories,” Penney points out. At PAX Scientific, he adds, designers frequently use a CAT scan—something da Vinci couldn’t have possibly possessed—to document natural objects, to study their inherit advantages inside out.

Molecular Architecture

Some might say Jenny Sabin specializes in blowing things out of proportion. To see her body of work is, in a sense, to see the microcosm of the human body in a larger scale, to literally get lost inside our own cellular structure.

Sabin, who teaches design studios and elective seminars in the Department of Architecture at the University of Pennsylvania, has a long-standing fascination with adapting biological processes to architecture. “I have been collaborating with molecular biologist Peter Lloyd Jones for close to four years now,” she says. “We formally co-direct a hybrid research and design unit called Sabin?+?Jones LabStudio.”

One of the outcomes of the Sabin-Jones partnership was an exhibit called Branching Morphogenesis, currently on display at Ars Electronica (Linz, Austria). The installation, in Sabin’s words, “explores fundamental processes in living systems and their potential application in architecture.”


images courtesy Sabin + Jones LabStudio.

The installation dubbed Branching Morphogenesis is the outcome of a collaboration between architect Jenny Sabin and molecular biologist Peter Lloyd Jones, as they adapt biological processes to architecture.

Constructed out of 75,000 tiny interconnected cable strips, the overall structure dangling from the ceiling resembles a piece of transparent, flexible, organic fiber, exhibiting the recognizable characteristics (perhaps more recognizable to biologists) of the endothelial cells that form the vascular lining of our blood vessels. Visitors are encouraged to wander within the maze-like tapestry of the installation. For researchers, the exercise lends insights into not only how cellular networks behave within a 3D environment, but also how new materials and fabrics might be developed for architectural use.

One of the software packages used by Sabin in the Branching Morphogenesis project was Generative Components from Bentley Systems, described by its creators as “an associative and parametric modeling system used by architects and engineers.” Through a combined use of programming and geometry modeling, the software allows users to automatically generate derivative shapes and variations of base objects. The automation is usually driven by user-defined rules.

“The software [gave us] a bottom-up approach to developing forms,” says Sabin. “We developed our own algorithms and scripts that ran on top of Generative Components.” The group used it in two ways. First, they used it to simulate the behavior of cell networks by extracting the rules and relationships they observed at the micro-scale. Next, they used it to filter through the actual scientific datasets.

The transformation algorithms developed by Sabin and her team are used to simulate, at the most basic level, the shapes and characteristics of individual cells, how they interact with nearby cells, and how they interact with the environment. “In one of our projects, we set up a number of cells and programmed how they would behave,” says Sabin. “Then, we modeled the overall environment in geometry. That let us observe the role that environment has upon specifying the overall form, function, and structure of cells.”

In putting together the Branching Morphogenesis installation (with the help of LabStudio design assistant Andrew Lucia and roughly a dozen rotating students), Sabin and her crew referred back to their parametric and associative simulation models to predict fairly accurately the volume of materials they would need to produce the piece in the desired dimensions.

In pursuit of biomimicry, Sabin encourages her peers to resist the temptation to copy the geometric shapes and forms discovered in natural surroundings (for example, a mushroom-shaped single-family dwelling, with leaf-shaped windows).

“I’m more interested in observing the dynamic behaviors found in nature and adapting them to architecture,” Sabin explains. “It would be easy for us to use the form, but to study nature like we did takes rigor and time. It also takes time to develop the computational tools needed for visualization. But for me, it has been incredibly inspiring to find possibilities of new materials based on biological forms. We might then build buildings that breathe—not in the literal sense, but in the way they interact with their surroundings and environments.”

Sabin’s advice to those starting out in biomimicry is, “Focus more on nature’s process, and less on the final form.”
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