May 1, 2005
Developers answer the question: What must happen next for manufacturing to embrace upfront CFD?
By Louise Elliot
Although CFD (computational fluid dynamics) has led the rapid growth of CAE (computer-aided engineering) technologies over the last few years, the technology is used by design engineers only irregularly. We asked a number of companies that offer designer-level CFD programs what needs to happen next to make upfront fluid analysis take off.
Overall, the participants agreed that greater awareness of the potential benefits and the tools available would be important to the next growth spurt. They also agreed that more intelligence built into the software would help drive this market—and that the availability of faster low-cost computer platforms and inexpensive memory were already helping to grow the market.
|This CFdesign image of the Seadoo Sea Scooter illustrates the integration of MCAD and upfront CFD. The simulation is fully associative with the native SolidWorks assembly and includes the full motion of the rotating prop. Setup took about 10 minutes, meshing was automatic.|
Among the stumbling blocks mentioned: in larger companies, dedicated analysts who feared losing their positions; in smaller companies, an unwillingness to spend scarce money on software that didn’t need to be used on a daily basis. All the participants define design engineers using CFD tools as degreed engineers (B.S. holders usually), or very experienced design practitioners.
Educating the Potential Market
After saying that business had increased fourfold over the last five years, Ed Williams of Blue Ridge Numerics adds that it could quadruple again in the next five years. “It’s an issue of awareness,” he says. “If we can show prospective users, especially those who have never used CFD and rely on building and testing physical prototypes, how the software works on their designs—it floors them.”
Even beyond the “Wow!” factor, he says, the breakthrough comes when they realize that they can learn more from CFD analysis than physical tests. “They can’t put sensors and probes everywhere. Being able to run two analyses in 30 minutes on their CAD designs grabs them. If they can see inside their own products, can see the results of multiple what-ifs that they can’t do with physical prototypes—they want the software.”
Blue Ridge grew its markets fastest during the recent recession. Williams points out that economic pressures led many of its targeted small to midsize companies to reduce staff and change the way they do things—and simulation technology benefited.
Arvind Krishnan of COSMOS says that part of the educational process is building awareness in the manufacturing sector that in addition to getting accurate results from CFD, they will create better designs faster and at lower cost.
“Most of our customers are first-time CFD users,” Krishnan says. “To teach them they can trust the results, we have almost 100 verification problems to which they have the answers, proved by a variety of methods, and we can match them with COSMOSFloWorks results. We also run benchmarks on products for which they know the results, making them more confident.”
|A COSMOSFloWorks screen shot showing a study of the effectiveness of cooling for different layouts of electronic components by plotting temperatures and visualizing trajectories of cooling fluid. Click on image to enlarge.|
Companies need to decide how many times they want to make and test prototypes, he says, and ask themselves how much money and time they can put into that. “Then they need to know that the software will show them more about the behavior of fluids than tests can. Too many people think of CFD as a research science, and they don’t know that in the case of products such as valves, which have functioned for years on accepted principles, they can optimize designs by using CFD software.”
He adds that in its areas of heaviest use— electronics, medical products, some consumer products, and industrial equipment—only 5% to 10% of designers use it, “but 80% could use and benefit from it.” (For more on CFD in electronics, see the sidebar “Specializing in a Single Industry” below or clickhere.)
Tying Midrange and High-End Use Together
Fluent, CD-adapco, and ESI CFD all make Tier One CFD—i.e., CFD with very complex physics that requires additional education to use successfully— and designer-level CFD programs. They have the advantage of being well known to larger companies with analyst staff—and the disadvantage of entering the upfront market later than their midrange competitors.
Andre Bakker of Fluent says that designers face complex problems, and need easy-to-use software (See the sidebar “Hosted Up-Front CFD Can Cut Costs” below or click here). “The problems can be difficult on the physics side—compression, cavitation, complex non-Newtonian fluids, and oils that are temperature-dependent. Despite such problems, they need software that gives reliable results.”
|This sequence of FLUENT 6.1 CFD studies of a bicycle helmet helped engineers choose an aerodynamic model for the British Olympic cycling team.|
In addition, because designers use fully realized geometry from MCAD, the geometry is often more complex than that used by analysts and laboratory scientists who create their own models. “So, designers need powerful software that’s different from what the experts use. Because they don’t have a lot of experience, designers can’t separate good and bad results—and they don’t have the time to learn to do so. As developers, we need to write software that can handle complex geometry with easy- to medium-complexity physics that’s fast, reliable, and safe. FloWizard will flag any questionable results,” Bakker says.
The Fluent Version 6 engine powers FloWizard—as STAR-CD and ACE Plus do for the design-level offerings from CD-adapco and ESI. Bakker believes that as experience with the upfront tools grows, users will be more confident. “The software is very fast. We used to have to use a Cray overnight for a problem that now runs in FloWizard in 30 minutes on a laptop,” Bakker says. “That’s a good selling point, because designers don’t want to wait for over an hour, whereas researchers using the Tier One software think they’re doing well if they finish in 50 hours.”
Dennis Nagy of CD-adapco says that the ability to move problems from STAR-CAD to a higher level program, either STAR-CCM+ or STAR-CD, gives buyers confidence. “We will either train their people and lease the software, or we’ll do the problem for them if the physics go far beyond the design engineer’s experience level. Although we target designers, we do warn companies that they may need greater capability,” he says.
|Polyhedral mesh of an airplane in STAR-CAT5 from CD-adapco.|
If a company has CFD specialists on staff, adds Nagy, “there’s often a cultural problem. The company may send all the problems to a central group just because they’ve always done it that way—and those groups are very self-protective. If they are open-minded enough to act as facilitators for wider use, including design engineers, the technology will spread into product development. But they often fear for their jobs and resist.”
He agrees with Bakker that the MCAD geometry used by design engineers creates some difficulty from a simulation viewpoint. For CFD, he points out, materials and surfaces are far less important than structure and texture, because the flow goes in and around, and the program needs to know the 3D volume to mesh and analyze.
Equally obstructive, Nagy says, is the unwillingness of people in smaller companies to pay for software that’s used only occasionally. “If, however, we can show that the benefits from using the software as little as twice a year will still pay for it—and it often does—they’ll be interested.” He believes that the more sales are made on the basis of cost justification, the more other companies will take notice and follow suit.
|This CFD-CADalyzer image shows the airflow around a motor. . (Model image courtesy of Sold Edge.)|
Neil Perez of ESI CFD thinks that in engineering departments segregated into design engineers and analysts, ideally CFD-CADalyzer can be used while designing, and then at the end of the design cycle, analysts can work with both that software and ESI’s ACE Plus, as well as other tools. “Analysts are reluctant to accept that designers can do fluid analysis,” he says.
|This image shows the CFD-CADalyzer environment. . (Model image courtesy of Sold Edge.)|
But if the company has no analysts, CFD-CADalyzer makes it possible for the designer to analyze—even though he doesn’t have access to extra conditions, where greater knowledge of the physics involved comes in. “The upfront tool is meant for initial analyses, using the native CAD model. It does automatic meshing, and this avoids the biggest area of possible error,” Perez says.
He also emphasizes that companies need to be educated to know that built-in limitations restrict the kinds of problems done by designers, and that designers and analysts don’t do the same job. “Engineering staff needs to be educated to work together, and the designer needs to know that he can learn a lot about the product with CFD.”All agree that there’s no silver bullet. The market is growing—and education, experience, and competitive advantage can only grow it faster.
Contributing Editor Louise Elliott is a freelance writer based in California. Offer Louise your feedback on this article through [email protected]