In case you missed them, two very good articles were published recently on the topic of CFD and simulation.
[The year is still “new,” right? I started writing this article on 03 January and am only getting back to it now.]
Tech Briefs magazine shared the results of their annual discussion with leading simulation software vendors in Industry Roundtable: Analysis & Simulation Software 2013.
And with a forward leaning slant, CAE Watch gave us their annual look at the coming year in computational fluid dynamics, CFD in 2014.
What We Learned from 2013
The eight industry executives interviewed by Tech Briefs provide a pretty good perspective on the state of analysis and simulation software based on what transpired in the previous 12 months.
Simulation is Good
They all agree that simulation is a valuable if not necessary tool for many industries, especially ones built around complex products. SIMULIA’s Dale Berry summed it up “Simulation is not only a necessity, it is a do-or-die requirement for survival in many industries today.”
The mantra is simple: simulate early and simulate often. By performing simulation early in the design process you’ll be more effective in influencing the design before it becomes too rigid (as happens as the design matures). By simulating often you’ll be able to more fully explore the performance envelope and parametric variations on the geometry.
[This is where a cynical reader usually feigns shock that simulation software vendors advocate more simulation.]
An interesting corollary to simulating early in the design process is that the CAD models are usually less mature – in other words, sloppier. While this won’t necessarily effect some types of simulation, it can play havoc with mesh generation for CFD. Of course, the need to defeature might not be as great because detailed design hasn’t started.
Testing Isn’t Going Away
As strong as the advocacy of simulation is, no one has drunk enough of their own bath water to believe the need for physical testing has disappeared. Simulation and testing have always worked hand in hand.
I can still remember back in the late 1980s when a CFD workstation – loaded with completed computations and ready to compute more – was taken to a wind tunnel test for a special aircraft with the purpose of verifying that things were going as expected or to figure out why they weren’t. If I really stretch my memory I can recall my first exposure to CFD while working one summer at the 10×10 supersonic wind tunnel at NASA Glenn (then NASA Lewis). The simulations were performed pre-test to guide the test schedule and post-test to validate the simulations. [And we actually discovered something about the numerics of the solution that had a bigger than expected effect on the results.]
You might be tempted to think that testing is real while simulation is not. But testing (and I’m thinking primarily of wind tunnel testing) is a simulation also. Putting a tiny airplane in slightly larger box and blowing wind over it isn’t really the same as flight test. Scale effects, interference effects, measurement accuracy, and the pesky detail about just how closely the model matches the CAD all lead to interesting engineering.
You have all heard this joke: No one believes the CFD except for the engineer who ran the simulation. Everyone believes the wind tunnel test except for the engineer who ran the test. But never forget that all good humor is based on a kernel of truth.
One recent example flies in the face of this advice against cessation physical testing. As cited in Desktop Engineering, Oracle Team USA used only CFD for all their fluid dynamic design in a successful run at the America’s Cup.
More Computing Power
Remember that advocacy of more simulation? It comes at a cost. Faster CPU, more RAM, bigger disk. And then there’s software license cost.
Fortunately, server clusters – both local and remote (aka cloud) – are available to fill that need. Plus, the software providers are targeting those platforms with their product development.
MSC Software’s Dominic Gallello hit the nail on the head when he said “Yesterday the computer was the bottleneck. Today, it is the engineer who has to interpret all the data.”
- The article begins “In today’s environment of doing more with less…” We should stop saying that because I’ve heard it for 30 years in this business. In this regard, there’s nothing different about 2014 from 1984. As I overheard one senior executive say shortly after starting my first job, “When things are bad here they are really, really bad. And when they’re good they’re not a helluva lot better.” [Or “not hella better” as the kids say.]
- ANSYS’ Barry Christenson and Altair’s Mike Kidder both deserve credit for pushing for CAE (i.e. simulation, performance) to be the language that bridges designers and analysts. This gets back to the core issue of designing for performance instead of geometry. [I will not hold it against Christenson for using the term democratization.]
- The award for best quote goes to CD-adapco’s David Vaughn for “2014 is the year that design optimization grows a beard.”
- I found it odd that two of the industry execs (Vaughn and Kidder) cited software licensing issues in the context of high performance computing. Kidder goes into detail by saying that software costs have not mirrored the commoditization of hardware.
What to Expect in 2014
Perhaps more interesting than looking back with 20-20 hindsight is looking forward and making predictions. On the CAE Watch Blog, Shengwei Ma is “ranting from the perspective of end users” about what’s to come in CFD during 2014.
Technology Is Not As Important As It Used To Be
About a year ago, Antony Jameson was quoted as saying that CFD has been on a plateau for about 25 years. Ma echoes this by pointing out the lack of exciting developments in CFD and the relative sameness of competing products. Given this environment, the cycle goes like this:
- Software vendor needs to make sales.
- Software vendor has no exciting new developments.
- Software vendor adds minor features.
- Software vendor brands this upgrade as new technology.
- Customer upgrades.
- Software vendor starts over at Step 1.
I think Ma is being a bit cynical. The overnight sensation business model wouldn’t apply to CFD even if it were real. (You’d be surprised how many years of preparation it takes to become an overnight sensation.) Plus, I’ve always believed in evolution over revolution when it comes to software development.
But I agree 100% with how Ma concludes this section of his article. Let me quote it here. “Building trust with potential users is more and more important for CFD software vendors.” Social media tools like blogs, Twitter, YouTube allow that trust to be built through a dialog.
More Is More but Less Can Be Better
Probably as a result of the software development cycle Ma cites above, we find ourselves with software that keeps getting bigger and bigger and you can state this in many ways. Ma says 99% of users will only use 1% of the software’s features. Or is it 90-10? Or 80-20? It doesn’t matter because the nugget of truth is there. Here at Pointwise we call them 2% commands because that’s how often they get used.
However, when you need it, a 2% command comes in very, very handy.
I agree with Ma 100% when he advocates vertical applications that target specific classes of geometry. In my opinion, the best opportunity for automating mesh generation is by targeting vertical applications like turbomachinery, aneurysms, wing-body, etc.
And this is why we architected our product with a scripting language that lets it be customized with macros and templates and why we freely share those scripts online. It’s why we added a plugin capability so users can export their grid and boundary condition to their own custom file format.
Back to Ma’s point about feature-bloat, interested readers should consider Clayton Christensen’s The Innovator’s Dilemma.
Meshing, Meshing, Meshing
I don’t know whether to feel belittled or buoyant that Ma says the top 3 problems in CFD are meshing, meshing, and meshing.
He cites the Catch-22: you need to generate a mesh to compute the physics but you need to know the physics to generate a mesh that will compute the physics accurately.
This is why my meshing friends advocate solution-adaptive meshing. But even that’s not a panacea.
I also don’t know of a single CFD code that will automatically – and I mean that literally – converge to an accurate answer given only a mesh and boundary conditions.
No one said CFD was easy. But Ma’s point is that as CFD begins to be applied by non-experts we really need to remove meshing as a potential stumbling block.
A Wealth of Open Source
Let’s begin where Ma ends: “open source CFD software will probably still only make the rich richer.”
If you equate open source software with free software it becomes somewhat paradoxical. How do you become wealthy with free software? Volume!
It seems that Ma’s point is that open source software’s drawbacks (including lack of strong 3rd party support) will limit adoption thereby continuing everyone’s reliance on commercial software – thereby making the rich richer. [Because everyone who works at a commercial CFD software company is filthy, stinkin’ Robin Leach rich.]
Clouds, GPUs, Webinars
- Ma believes everyone will eventually migrate to the cloud for its “pay per use” license model. But I’m still not convinced that there is a consensus opinion of what exactly the cloud is good for.
- Ma seems intrigued by the potential benefits of GPU-accelerated CFD codes but then points out that the coding issues involved are non-trivial [very true] and the graphics cards themselves aren’t cheap.
- Ma thinks most webinars are a waste of bandwidth because too many are simply self-promotional instead of being educational. Like any other medium, webinars can be abused.
Like I wrote in the opening, two very interesting articles that I recommend you read. And even though I may sound somewhat critical of Ma’s forecasts, I applaud his courage in making predictions.
Let me know what you think in the Comments below.
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