IMAGINiT Manufacturing Solutions Blog

CFD Analysis Consulting - interview on LifeUpfront CAE Blog

Check out our recorded interview on LifeUpfront.com.  Ryan Stamm, Director of Business Development for
the IMAGINiT CFD services group joins Jeff Waters on LifeUpfront.com.  Ryan discusses our unique and incredibly successful approach to CFD analisys consulting services.

Check it out... http://lifeupfront.com/2013/06/25/ryan-stamm-imaginit-cfd-consulting-rand/

 

CFD Analysis – Solving Everyday Problems

Many mechanical engineers I know have a knee jerk reaction at the mention of CFD analysis. Most often is they quickly pigeon hole it as something those crazy aerospace engineers use for aerodynamics on the space shuttle.   Or they dismiss it as not applicable to anything I’m working on. The truth is that
the vast majority of CFD analyses are applied to products that we use every day. Products like computers, cell phones, car radios, stoves, ovens, the office building you’re sitting in. The value of CFD analysis is unlimited in product development. I’m writing this post because I want to help engineers remove the limiting perceptions of where CFD technology can be leveraged.

Here’s an example that got me charged up. An everyday griddle for the kitchen. Think pancakes and French toast… CFD for griddle design. Makes sense when you consider the goals for even heating distribution and lowered energy consumption. Wonderful thermal optimization… This was a project with Spectrum Brands http://www.spectrumbrands.com on their latest griddle design.

Our team worked directly with Jacob Smith, Sr Mechanical Engineer and below is a comment he sent our way. You’ll see why I mention it got me charged up. Hopefully, somewhere out there is an engineer this will help by spawning some new ideas…

“IDP’s collaborative consulting model fits very well with how we develop new products at Spectrum Brands and I cannot say enough about their expertise and value-add compared to previous CFD consultants we’ve used.  From the beginning they were very clear of the actual problem we were trying to solve and clearly communicated all results in that context, which greatly enhanced our product knowledge, eliminated exploratory testing and will allow us to present a solid business case to marketing and NPD on a recent griddle R&D project.  We’re already strategizing with IDP on our next few projects.”

Jacob Smith – Sr. Mechanical Engineer, Spectrum Brands

The most expensive belief in CFD analysis

My job is talking with engineering companies about solving their flow and thermal design challenges with CFD analysis and quantifying the business reasons for doing it. Invariably the business case involves cost and return, risk mitigation, reduced material and testing costs, increase product performance, lifetime etc. Each week, on average, I speak with 15 different companies and one single idea prevails as the most expensive belief in all of CFD analysis. Caution! This might ruffle a few feathers.

Yesterday I chatted with an engineering manager at a mid-size company. He’s responsible for a team of 6 mechanical engineers that design four product lines. His engineers all do CAD, testing and even manufacturing quality assurance. None of his engineers have a particular slant or background with thermal or fluid dynamics; let alone CFD software. Given the current challenge his team is facing - to pack additional higher wattage components into an existing housing AND keep the thing cool AND have it done in a few months to fulfill a customer order I was astonished at his plan… I asked him about the scope and how our team might help and he said… “we have some kind of CFD software we got, so we’re good.”

Since the team simply has “some kind of CFD software” they’ll just pick it up and get reliable answers to make good decisions. Wow! The idea that just having software solves problems is a true belief out there. This belief wastes enormous amounts of time, money and effort in the engineering world. We see it all too often and frankly, it’s troubling. I wish statistics existed that could shed light on how much time and money companies spend wrestling with analysis software before it becomes shelf-ware after being sold an “easy to use” solution.

To be clear, there is no doubt a place for CFD software at many companies. I believe it’s only successful when it’s an engineer assigned to being the CFD analyst. And even then it’s not always the best place to invest resource and money.

Think of this. Our company deals with hundreds of thousands in taxes. Corporate tax code is an amazing thing especially dealing with multiple state offices. Perhaps one of those wonders of the world even. It would be easy to fall into the belief trap that all we need to do is get Turbo Tax software. But we don’t. In fact, we don’t actually do our taxes in house at all. We hire an outside professional tax firm for that. I was talking with a friend about this blog post and he asked me when we would hire an accountant on the staff. Why? That would be a huge investment of salary all other costs associated when we only need to spend a few thousand each quarter to get the project completed. (By the way, by professionals who know our company and our goals and know the code inside and out.) We know we get the right results with confidence every time without burning our time away from our core business – CFD analysis services.

The point I’m trying to strike at here is that just having CFD software doesn’t solve design problems. Typically it becomes a time waster trying to get it to work over and over.  

I know that somebody out there is gonna rip me up for this one, so let me have it.

Is CFD an Exact Science?

As a CFD analysis consultant I have been subjected to the question "Is CFD Exact?" many times.  How exact is exact,exactly?  Confusing isn't it?  The answer really depends on CFD analysis objectives...

I've been asked to carry out results data to 3 or 4 decimal places!  Really?  Do results showing 4.015 psi drive product development in a different direction than 4 psi?  If so, you don't need CFD simulation, you need a professor and enough capital to embark on a 6 month research project.  Don't get me wrong, CFD analysis can be exact!  However it requires a high degree of scrutiny and more time to capture every minuscule detail.  I come across many engineers who feel the need to include every detail is required to derive any value from simulation.  This cannot be further from the truth.  CFD can be exact but CFD does not have to be exact to drive product development decisions.

CFD results should always be verified with hand calculations and various sanity checks to ensure their validity; however, CFD being a mathematical model constrained by user inputs is inherently different than the physical world so differences in results should be expected.  If an initial baseline analysis shows a 10% discrepancy with physical testing does that mean there is no value in the analysis results?  What about the power in visualizing the flow fields, temperatures gradients, and other trends not accessible through physical testing or hand calculations?  This insight, and it’s interpretation,  will provide the information required to make informed design modifications.  As long as analysis assumptions are maintained across design configurations and sound engineering judgment is used, the result yielded will be a qualitative comparison of which design is better.  Given enough time and resources CFD can be spot on; but it does not have to be if developing a better product (performance, cost, weight, ...etc.) with less time and testing is your goal!