CFD's Image Problem

“So, what do you do?”

Have you been on the end of one of those long silences, when you tell someone you’ve just met, that you do CFD? A potential conversation stopper at a party. But a killer blow in a sales conversation.

Below are just some of the objections that I’ve heard whilst talking to prospects. Some are objections to CFD consultancy. Some are objections to the very idea of CFD. Some of them are misperceptions and can be gently corrected. Some of them can’t easily be countered at all. Some of them are plain wrong-headed. But if your prospect believes it’s a problem, then it’s just become a problem for you too.

Here, in no particular order, are 10 of the more often repeated objections to getting involved with CFD and some ideas for how to counter them:

1. “It’s too expensive”

Cost was one of the areas highlighted by several of the respondants in my recent expert roundup on CFD trends. In particular, how hard it is to find out how much it actually costs to get up and running with CFD software. Richard Smith of Symscape summed it up – “it’s a case of - if you have to ask, you can’t afford”. Perhaps it’s not a surprise that CFD is widely considered too expensive to be economic, especially if you only have a patchy need for it.

If you can demonstrate a positive return on a prospects CFD investment then you can put this one to bed. If you can link fixing a problem with CFD to increased product sales. Or to lower return rates. Or lower total cost of ownership. Then what was once “too expensive” can become “we’d be crazy not to”.

2. “It’s not the real world”

Why is it so much easier to trust numbers from the real world than from the virtual one? It’s not like physical models are always the same as the end product. Scale issues, detail levels, model supports and intrusive measurement equipment are just the start of a long list. But there’s just something about combining a tangible object with a moving fluid that trumps virtual testing at some psychological level.

Maybe CFD can counter this with more data, more insight and more answers? But this is a tricky one.

3. “Too difficult to understand”

CFD produces a lot of data, even a small model spawns more data than your average experimentalist or development engineer is used to. What is important? What do I need to pay attention to? What can I ignore? How can I combine some of these data into something more understandable? What’s actionable? CFD data is overwhelming and difficult to interpret. Especially for a novice. Don’t forget – there’s no such thing as common sense.

As a counter, reduce data overload & present the most important factors first. If drag is important, plot surface drag contours not pressure contours. If surface flow is important use simulated oilflow, not contour plots of individual vectors. Trivial examples, but you get the idea.

4. “It’s too slow”

CFD processes have always been a little more tortoise than hare. It didn’t matter much if it took a day to put a model together, if it then took 3 days to run it. Maybe this perception just hasn’t moved with the times? Maybe it’s propped up by consultants who take a long time and charge by the hour?

Either way it doesn’t really fit any more. If you’re doing it yourself in the spare cycles of an office workstation then maybe it is slow. But in the era of on-demand computing there’s plenty of opportunity turbocharge your CFD process. So much so – you probably won’t be able to CAD your next idea before the current one has finished.

5. “It’s too time consuming”

The time required to get started with CFD is significant. Especially once you factor in training, getting support and actually doing the work. It’s a burden that a small design team can’t easily take on. If your CFD load can’t justify a CFD dude then it gets even worse.

The obvious fix is to stop doing it yourself and offload it to someone who already has their 10,000 hour badge. But then I would say that wouldn’t I?

6. “It’s not useful”

“So they went away, did an ‘optimisation’ and came back recommending something that we couldn’t make – the whole project just wasn’t any use to us” said the prospect, describing his last encounter with a CFD consultancy.

It’s easy to get wrapped up in the “anything is possible” virtual world. But occasionally you need to check things from another perspective. Put your engineer’s cap on. Or your CFO’s bowler hat. Or your stylist’s beanie. But what if you don’t have all of these hats? Just talk to the real people and make sure what you’re doing is useful – to them.

7. “It’s science fiction”

To a 30 year old manufacturing company, just starting to embrace 2D CAD – CFD is science fiction. Done by geeks – for geeks. Not in their wheelhouse.

An easy counter to this is to forget about the tools. Leave talk of CFD for much later (if at all). They don’t understand & you’re putting them off. Talk to them about the types of problems you can help them solve and what that could mean for their business. As long as you deliver they probably won’t care what magic you used.

8. “It’s Wrong”

Some people just can’t get past the idea that they might invest all of the necessary time, money and effort into something that will still be “wrong” by some objective measure. That mental baggage won’t let them see any utility in wrong results. This mindset is hard to overcome – move on?

9. “It’s too easy”

OK, so I’ve never actually heard a prospect say this. But I have noticed something. It’s become very easy for a novice to produce some results. Whether they correspond to what the new CFD-er thought they were modelling is another matter. This can quickly lead to their CFD models, and CFD in general, being consigned to the bin. “We’ve tried that & it didn’t work.” And with that the CFD sales process just got a lot harder, ironically, due to the software getting easier.

10. “It’s too difficult”

More or less the opposite of the previous one. It describes those clients who picked up OpenFOAM (“because it’s free”) and then just couldn’t get it to do what they wanted. It’s not easy for a novice CFD-ist to produce meaningful results, that they can take action on, in any CFD package. It’s borderline impossible in OpenFOAM. As previously, CFD gets consigned to the bin and the bad smell lingers for a long time. You’re going to need a whole case of Febreeze to get these clients on board the CFD train.

What variations on these have you come across? Maybe you were selling yourself or a CFD code. Or maybe you were just trying to sell your boss on why you should adopt CFD? Have you got any particularly good objection busters? Please, share them with the rest of the class (or at least with me).