did any one seen some frame cfd calc
if yes where
cees
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did any one seen some frame cfd calc
if yes where
cees
http://www.entertainmentengineering.com/...ex.html?page.23.html
Just search on “Trek” and “CFDesign” and you should find a bunch of stuff…not a lot of detail, but interesting nonetheless.
http://www.entertainmentengineering.com/...ex.html?page.23.html
thanks but pic are all over the net i want to see calc !!(also meaby with pic meaby pressure info and some differant drag info)
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not sure specifically what you are looking for, but http://www.cd-adapco.com/press_room/dynamics/25/tourdefrance.html has rider included, and pretty pictures to boot! nothing makes the hours of sitting for your mesh to develop worth it in the end like a gradient picture of the results, mmm…
We have a pedantic CFD program here at work. I’ve done a few “runs” for various buildings (I’m a mechanical engineer by trade) and I’ve learned several things.
It’s really complicated to do. Accurately modelling the object is extremely difficult and time consuming. With our program, I don’t think a model of a bike is a realistic possibilty as the 3D grid (blocks) doesn’t work very well with bike tube shapes. Therefore modelling different frame styles would be nigh on impossible. It takes AGES to do multiple runs to achieve ‘stability’ for realistic answers
I could probably do a rudimentary version, like a lego bike, but the results would be pretty much worthless except for the pretty pictures of the flow arrows. Might be impressive to see for the uninitiated, but useless in computational terms. Not the best use of a week of my time, that is for sure.
I would be interested to see what could be done with a decent CFD program however, particularly with different frames, with validation from real wind tunnel tests.
Or I could just ride a Cervelo P3C and be done with it! 
http://www.entertainmentengineering.com/...ex.html?page.23.html
thanks but pic are all over the net i want to see calc !!(also meaby with pic meaby pressure info and some differant drag info)
I think you may have to actually PAY for something like that
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I would be interested to see what could be done with a decent CFD program however, particularly with different frames, with validation from real wind tunnel tests.
so what is in your opion a good cfd program?
as with a talk today with a aerospace engineer and cfd specialist
he does not trust any commercial cfd program like ansys or fluent to name a few
some he say you cannot trust their drag numbers becuase the calc of these numbers are too complex
but you can see pressure and velocity and some other things
but reall numbers concerning drag he said no way!!
as i have lot of windtunnel test of differant frame’s and other equipment so i can compare these to what the program calc
and never see a number match what measured in the wind tunnel
but we also test with wind flow on video and realtime vortex of the air partical
this is something developed here and used in special aerospace center
I only have experience with the “Air” CFD program. I don’t even know the names of any others. Our company directors looked at others a while back and found them to be crazy expensive. Our program works well enough for our purposes (to impress our uninformed building clients) so we continue to use it from time to time, when they are willing to pay us to do it. We use it most often to determine air tempertures and air flow patterns in office building lobbies for example. Takes about a week of work to get dependable answers and there is a certain amount of simplification of the model and some selective caressing of numbers to get it to display reasonably 
Works fine for that, but that’s about it.
From what I’ve been able to figure out, the program appears to be some PhD students thesis project from about 20 years ago. It’s been going a while and has been added to by the guy, who is now a professor in Sydney Australia. It works for air flow and temperatures in and around buildings, plus works pretty well in simulating fire conditions within buildings. The run time for any sort of accuracy is pretty long so is very time consuming and frustrating to use and to de-bug errors in the model. Regardless of how big I make my grid, I always seem to make it too fine and that drives up the accuracy of course, but kills it time wise. Large grids are just too coarse for me to believe the results.
“but you can see pressure and velocity and some other things
but reall numbers concerning drag he said no way!!”
Interesting point of view. How does he explain getting velocity and pressure correct, but not drag? With velocity and pressure, it’s straightforward to integrate the stress tensor over the body surface to get drag. I think it’s safe to assume we’re dealing with incompressible, Newtonian fluids, no?
“but you can see pressure and velocity and some other things
but reall numbers concerning drag he said no way!!”
Interesting point of view. How does he explain getting velocity and pressure correct, but not drag? With velocity and pressure, it’s straightforward to integrate the stress tensor over the body surface to get drag. I think it’s safe to assume we’re dealing with incompressible, Newtonian fluids, no?
CFD is not your thing, right? So WhyTF are you chiming in? I mean, seriously!
Edit: Just googled you. Looks like I won’t get that Sandia job!!!
you talking to me paulo???
No, I’m talking to Anthony Geller, Sandia National Laboratories.
Maybe you can get me a job, Cees? Does it rain a lot in Holland? I don’t like the rain much…
ok ,understand
rain mmmmmmm 10 cm of hail today so and yes lots lots or rain
well all global warming i guess
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“CFD is not your thing, right? So WhyTF are you chiming in? I mean, seriously!”
I don’t know if CFD is my thing or not. if you Googled me, you could have checked my Pubs and can decide for yourself.
But since you have implied previously that CFD is your thing, maybe you can explain to me what field variables go into calculating the drag on an object other than the pressure and velocity. Seriously.
I’ve had some experience with the Fluent software for analyzing flows over HPV’s. Not the simplest to work with, but a good program if you can get your hands on it.
I’ve had some experience with the Fluent software for analyzing flows over HPV’s. Not the simplest to work with, but a good program if you can get your hands on it.
I’ve been using CFDesign (Blue Ridge Numerics) coupled with Pro/Engineer (solid modeler) to look at electronics cooling designs. It’s VERY easy to use.
I haven’t been able to try it out on any aerodynamic drag problems yet so I can’t comment on how well it does on those types of analyses…plus, the version I’m using doesn’t have the “rotating/moving component” option (I wish it did)…
I’ve had some experience with the Fluent software for analyzing flows over HPV’s. Not the simplest to work with, but a good program if you can get your hands on it.
so i have also a project for a hpv , so would be interested in results and the flow and pressure as well other data wich fluent version?
i think for a frame you do not need moving components parts …
, the version I’m using doesn’t have the “rotating/moving component” option (I wish it did)…
i think for a frame you do not need moving components parts …
, the version I’m using doesn’t have the “rotating/moving component” option (I wish it did)…
If you’re just looking at the frame, no. But, if you wish to include any “interactions” with moving objects (i.e. wheels, legs, etc.) it sure would be helpful
, legs, etc.) it sure would be helpful if we only could model human easy
even with a laserscan
not the same ,as when its moving with muscle changes and all
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