I have written many times that I am a huge fan of Desktop Engineering Magazine. There was an interesting article recently on Conceptual Design. It is my favorite type of article. They poll four different representatives from four different vendors (Rhino, SolidWorks, Siemens & Autodesk) and ask a variety of questions to see how each tool responds to demands of the market.
The article was near and dear to my heart. Conceptual design is something I live and breath everyday. Each rep from the various vendors had some really cool and unique views of where their products add value in the conceptual phase of design. I came across the following quote and almost fell out of my chair.
“For example,” he says, “wind tunnel or tank testing often is not all that expensive [when] compared to setting up and running CFD analysis. It is often easier to make the design iterations by playing around with a handful of clay and turn the wind tunnel back on, than it is to change the computer model and rerun the CFD analysis. But structural analysis of a large building design has to be done virtually. Physical analysis is economically impossible.”
He was designing a brand new line of poppet valves. He was responsible to ensure the pressure drop was within a certain range, as well as determining the spring needed to maintain stable flow over a wide range of flow rates. His ultimate goal was to have three prototypes (3 different sizes) ready to be outsourced for final physical testing. I asked how much were the outsourcing costs? $8k for three...whoa! Seemed steep to me, but I am all about virtual reality, I suppose.
So, let's say you didn't perform an Upfront simulation of the model and your three original designs were not up to snuff. So, you had to re-do the prototype testing. You have just justified the $$ for an Upfront CFD tool. But this is really just the tip of the iceberg. In reality if you had the simulation tool in place you could confidently pay for one round of validation testing at the end of the design cycle. But, more importantly, the simulation models would allow for innovative design that is not possible in the physical testing world. You aren't able to get in there and peel things away to see inside where the action is happening in a wind tunnel. You are limited on the data available and you induce inaccuracies with the measuring devices.
So, back to the article at hand. I think I understand where the guy was coming from. In the past, CFD was the big gorilla in the room. Everyone was afraid to go near it. It was too "expensive". Things have changed drastically over the years. More and more everyday. Whether its a wind tunnel, a flow bench or a thermal chamber or even a thermal camera, there are significant investments of time and materials required.
My friendly advice is to fire up Google and do a search for Upfront CFD.
“For example,” he says, “wind tunnel or tank testing often is not all that expensive [when] compared to setting up and running CFD analysis. It is often easier to make the design iterations by playing around with a handful of clay and turn the wind tunnel back on, than it is to change the computer model and rerun the CFD analysis. But structural analysis of a large building design has to be done virtually. Physical analysis is economically impossible.”
It is interesting how many people share the same sentiment. The fact is there are only few instances where this may be the case. I was talking to an engineer at a very well-known valve manufacturer about this and he shared a few numbers with me.
He was designing a brand new line of poppet valves. He was responsible to ensure the pressure drop was within a certain range, as well as determining the spring needed to maintain stable flow over a wide range of flow rates. His ultimate goal was to have three prototypes (3 different sizes) ready to be outsourced for final physical testing. I asked how much were the outsourcing costs? $8k for three...whoa! Seemed steep to me, but I am all about virtual reality, I suppose.
So, let's say you didn't perform an Upfront simulation of the model and your three original designs were not up to snuff. So, you had to re-do the prototype testing. You have just justified the $$ for an Upfront CFD tool. But this is really just the tip of the iceberg. In reality if you had the simulation tool in place you could confidently pay for one round of validation testing at the end of the design cycle. But, more importantly, the simulation models would allow for innovative design that is not possible in the physical testing world. You aren't able to get in there and peel things away to see inside where the action is happening in a wind tunnel. You are limited on the data available and you induce inaccuracies with the measuring devices.
So, back to the article at hand. I think I understand where the guy was coming from. In the past, CFD was the big gorilla in the room. Everyone was afraid to go near it. It was too "expensive". Things have changed drastically over the years. More and more everyday. Whether its a wind tunnel, a flow bench or a thermal chamber or even a thermal camera, there are significant investments of time and materials required.
My friendly advice is to fire up Google and do a search for Upfront CFD.
1 comment:
Iterative windtunnel testing less expensive than iteratively changing a CFD model (either upfront OR traditional CFD)??!??!
That's just a dumb, false statement.
Let's say your company actually owns its own windtunnel (unlikely). That's probably millions invested in the facility, the people to man it, and the people to craft those clay prototypes. A little CFD expertise and software would be a mere drop in that bucket.
More likely, your company would look at renting time at someone else's windtunnel. Ever priced that out? More importantly, good luck getting in the queue with other renters ina reasonable amount of time. And, good luck making a change based on the results and trying a new design anytime soon!
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