December 17, 2011
FLO Cycling - How CFD is Changing the Cycling Industry: A Bill Clark Interview
I was recently able to sit down with Bill Clark, the Vice President of Global Operations for CD-adapco, to discuss how Computational Fluid Dynamics (CFD) software is revolutionizing the cycling industry. At FLO Cycling we used CD-adapco's STAR-CCM+ CFD software. For us it was a game changer. It allowed us to drastically lower our R&D cost, reduce time to market, and most importantly improve our aerodynamics. It's our firm belief that CFD aided design is the way of the future and Bill helps explain why.
During this interview you'll learn about CFD software, how it's shaping the cycling products we use today, and how it will affect the products we enjoy in the future.
Bill Clark graduated from Purdue University with a BS in Aerospace Engineering and from Duke University with a MS and Ph.D in Mechanical Engineering with a specific concentration in the simulation of unsteady aerodynamics and aeroelasticity of gas turbine engines. Since joining CD-adapco in 2000 as a consulting engineer, Bill has moved on to become the Senior Vice President of Global Operations.
FLO Cycling: What exactly is Computational Fluid Dynamics Software?
Bill Clark: Simply put, Computational Fluid Dynamics (CFD) Software is a tool that allows an engineer to simulate or predict, on a computer, how a system (perhaps a full bicycle and rider) will perform once built. The beauty of CFD software, is that prior to going into the wind tunnel for final validation, multiple design configurations subject to a variety of operating conditions (headwinds, tail winds, multiple riders, etc.) can be assessed to hone in on an optimal design. This obviously reduces cost and time associated with building multiple prototypes and ultimately results in a superior product as more of the available design space has been explored.
FLO Cycling: How did CD-adapco get its start in the CFD industry with STAR-CCM+?
Bill Clark: CD-adapco has been developing and using simulation software for more than 25 years. Our original product, STAR-CD has been used extensively in the automotive, aerospace and energy sectors since the late 80's. Around 2001 we realized that we needed to "go back to the drawing board" and create a new tool that would take advantage of our prior experience as well as new technologies in hardware (computer chips and architecture) and software (programming languages) that were previously unavailable. While a costly investment, the result was that CD-adapco could not only more effectively incorporate more physics into the simulation tool itself but also bring simulation to a new community of engineers and designers that had previously considered CFD out of reach. STAR-CCM+ has proven to be a fantastic investment that was quickly adopted by the user community and is now heavily responsible for shaping the CFD simulation industry of tomorrow.
FLO Cycling: How does Computational Fluid Dynamics Software compare to designing products in a wind tunnel/real world application?
Bill Clark: As I previously mentioned, CFD is generally used in conjunction with wind tunnels and real world testing. I believe that the most successful and innovative companies find ways to leverage the speed and detailed information provided by high fidelity CFD simulation and their testing programs. Dozens (if not hundreds) of permutations can be tested in a "virtual wind tunnel" using CFD and a computer. Only the best candidates need to be physically prototyped for "real world" testing in the wind tunnel. One thing to understand is that in physical testing, the engineer only gets a limited set of information based on how the component is instrumented (drag, pressure loads, etc). In simulation, the engineer can see not only this limited information, but flow details that would not even be possible to capture or visualize with physical testing. It is precisely this difference that makes simulation an invaluable asset to any product development team pursuing innovative designs.
FLO Cycling: What is the accuracy of STAR-CCM+ data output when compared to real world results?
Bill Clark: I wish I could say that it is always 100% consistent with experimental results but unfortunately that is not the case (yet!). This is why there needs to be a two pronged approach which couples simulation to experimentation. In many cases, simulation results are in near perfect agreement with information obtained from the wind tunnel or other physical testing. In other cases, depending on the physics being modeled (detailed chemistry, complex flows with phase changes, or exotic operating conditions for example) the mathematical models are not 100% faithful at predicting reality. But even in these cases, while simulation may not provide an accurate, absolute value, the trends associated with design changes are often correctly predicted. This is of tremendous value when considering design permutations. Our job is to minimize the differences between mathematical models and reality. Fortunately, CD-adapco has a great team of mathematicians, physicists and engineers dedicated to just that activity.
FLO Cycling: What differences in time to market do you see when using STAR-CCM+?
Bill Clark: It really depends on the product being developed. For example, an aircraft engine has a design cycle that spans years. Proper use of simulation could easily shorten the time to market by 6-12 months and result in a more optimal product once it reaches the consumer. My understanding is that the design cycle in the bicycle industry is quite a bit shorter, so the impact on time to market may be measured in weeks or perhaps a few months. Even this, however, can be the difference in being viewed by consumers as a flight leader or a follower.
FLO Cycling: How has CD-adapco/STAR-CCM+ helped the cycling industry make advances in aerodynamics?
Bill Clark: I think CD-adapco's contribution is that we enabled the creative and hard working engineers that are out there designing the next generation cycling products to explore design space that they had neither the time nor resource to consider. As a result, the products on the market are better today than they have ever been. We strongly believe that our technology and people facilitate innovation while simultaneously reducing the associated development costs and time. We understand our role in this process is to be supportive. I guess you should think of us as the engineers' domestique. We are truly grateful to be able to participate in this exciting arena.
FLO Cycling: What cycling specific projects has CD-adapco's software been a part of?
Bill Clark: I am aware of three specific projects [in addition to FLO Cycling] (there are probably more) where our technology was used to improve cycling products. These are: Felt's development of their DA and AR lines of TT and road bikes, respectively; Optimization studies carried out on Zipp aero wheels; and most recently, the development of Cervélo's next generation S and R series aero bikes (http://www.cd-adapco.com/downloads/videos/cervelo.html). While the real kudos must go to the engineers who applied simulation technology to make their products the flight leaders they are, we are very excited to be able to support these initiatives. In fact, Phil White, co-founder of Cervélo, has recently agreed to being a keynote speaker at the upcoming STAR Global Conference 2012 (http://www.cd-adapco.com/minisites/global12/) to address the importance of simulation in the design process. Additionally, Cervélo has agreed to provide an R5 bike as a giveaway for those in attendance!
FLO Cycling: What trends are you seeing in the field of Computational Fluid Dynamics Software?
Bill Clark: As applied to the cycling industry, I see three trends. First, there is the general acceptance of simulation by the designers and their management and as a result, simulation is the norm rather than the exception. Second, the organizations that we have had the pleasure to work with are now performing automated optimization studies that efficiently and intelligently search the design space for the "best" design. No longer does the designer just submit one job at a time, evaluate the results, make a design change and repeat until the time runs out. Instead, multiple simulations are set up at once and all the results can be reviewed and used to construct a viable design space. This space can then be explored quite quickly to approach a true optimum design more rapidly. Finally, I see that the model complexity itself has increased. Early on, designers would only look at their component in isolation - the wheel without the frame, or the bike without the rider. Now, because the computer and software are relatively inexpensive the designer can analyze the complete system - which is what we should really be trying to optimize anyway.
FLO Cycling: Where is CFD software headed in the future and how will these advances in technology affect the cycling industry?
Bill Clark: This is a great question as there is so much change presently going on within the industry. My belief is that we are well on our way to making CFD accessible to people who are not "classically trained" in CFD or simulation. In the past, these types of tools (CFD, FEA, CAD) were reserved for engineers with graduate degrees or people with masochistic tendencies. While we must always be looking to incorporate new physics models to extend the applicability of our tools, our biggest push is in advancing the user experience. We need ANY engineer to feel comfortable and confident when reaching for STAR-CCM+. This means that how the user interacts with the software and, of equal or perhaps greater importance, how our company supports the user needs to be continuously assessed and improved. We have some very exciting things to report in this regard, but that is another story.
FLO Cycling: What advice would you give your peers when it comes to utilizing CFD software when designing aerodynamic cycling products?
Bill Clark: If you aren't using CFD routinely now, you are behind. Often times the optimal design is not the most robust design (i.e. heavily impacted by variations in manufacturing) so one needs to not only maximize performance but minimize the impact of variability. This can only be accomplished through the application of simulation. This is an exciting time to be developing aerodynamic cycling products. While it is our hope to have an opportunity to work with you directly, but even if you aren't using our solution, as a cycling enthusiast it is clear - the market will demand products that have benefited from aggressive and innovative design studies that rely heavily on simulation. I always look forward to my next trip to the local cycle shop to see how the engineers have advanced the state of the art. I'm never disappointed.
We hope you enjoyed the interview. We want to thank Bill Clark and Lauren Gautier over at CD-adapco for taking the time out of their busy schedules to help put this interview together. To learn more about CD-adapco and STAR-CCM+ you can visit there site at http://www.cd-adapco.com/. For more great content, please register for our free monthly newsletter at the top of the column on the right. We send links to all the articles we post during the month. Post your comments below to get the conversation started.