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Blue Bomber Man 03-17-2009 10:11 AM

Needed: CFD analysis on a SolidWorks assembly drawing
 
Unfortunately I have no way to perform a CFD on my assembly since I don't have access to FloWorks (the part of Solidworks that does CFD). So I am hoping to either find some free software that can perform the CFD from my .sldasm file or someone to perform the CFD for me to determine my project's Cd.

If you want to see screenshots of the project visit the Fossil Free forum for the post that involves my custom EV build or visit the blog in my signature.

Thanks!

big_dave 03-17-2009 04:59 PM

I've got solidworks and floworks, I'll do the calculations if you want.

I should add I am a beginner, so if you let me know exactly what you need doing I'll be happy to give it a go.

Blue Bomber Man 03-17-2009 05:10 PM

1 Attachment(s)
Awesome Dave!

I still need to clean things up and finish the rear of the vehicle. I also want to figure out how I can direct air around the wheels efficiently, so probably in a week I will try and hit you up on that offer and I'll send you a zip file of the whole assembly.

Here's some eye candy from PhotoWorks.

http://ecomodder.com/forum/attachmen...1&d=1237324023

I just started playing with those tools today so I'm pretty limited on what I've been able to do with that so far. It takes my computer about 4-5 images to render the images in Photoworks, but I think they will come out really nice once I learn all the in's and out's of that program.

big_dave 03-17-2009 05:20 PM

My friend made a fairly basic model of his Polo and it takes about an hour to do the calculations in FloWorks, and that's on my workstation (8 x 2.83Ghz).

Once I've worked out why I don't receive an email on new posts I'll look out for your reply.

aerohead 03-17-2009 05:23 PM

analysis
 
If you bear in mind VW's 1-liter car you could easily reach Cd 0.15.If you move the wheels out away from the chassis,mono-posto style and carefully fair in all suspension and wheels,you might squeeze Cd 0.11 as with Sylph.Go to the fish section of your supermarket and buy a frozen mackerel.You can take all your dimensions from that and scale it up.

Blue Bomber Man 03-17-2009 05:56 PM

I'm worried that putting the wheels on outriggers will increase the frontal area in way that is not offset by the decrease in Cd.

Thoughts?

aerohead 03-17-2009 06:09 PM

outriggers
 
Quote:

Originally Posted by Blue Bomber Man (Post 93030)
I'm worried that putting the wheels on outriggers will increase the frontal area in way that is not offset by the decrease in Cd.

Thoughts?

It is an issue,although it does widen the tripod base for the rig.The Sylph won't tip,is very stable as reported and at Cd 0.10-11 ( windtunnel at JPL I think ) approaches the lower limit for Cd in ground-effect.------------------------------------------------------------------- I'm running an old air-cooled VW torsion-bar double-tube setup on my Frankensteinian mini-Hypercar project.I'll pay a penalty in Af,but it will also stand up to the monster pot-holes around here,and if I get slammed at the front in a wreck,may save my bacon.-------------------------------------- You've got the right idea with the two-up front,single rear trike,as it provides the greatest potential for drag reduction.-------------------------------------------------- I like your graphics,keep us up-dated.

Blue Bomber Man 03-17-2009 06:33 PM

I will have to think about it once I get a better idea on how my current build performs. The idea is to keep all costs down, so I certainly make all efforts to improve aerodynamics so that I can keep the drivetrain costs down. I think that having the wheels on outriggers and then trimming them out so that they are aerodynamic could be a bit cost prohibitive, but I think I will definitely play around with it when I get more fluent in Solidworks.

Good chance I will look into a larger 4-wheel design with fully inclosed wheels that has a bit more ground clearance then this design where the wheels will almost be like on stilts, kinda like Aptera's rearwheel except for all 4.

aerohead 03-17-2009 06:45 PM

Quote:

Originally Posted by Blue Bomber Man (Post 93037)
I will have to think about it once I get a better idea on how my current build performs. The idea is to keep all costs down, so I certainly make all efforts to improve aerodynamics so that I can keep the drivetrain costs down. I think that having the wheels on outriggers and then trimming them out so that they are aerodynamic could be a bit cost prohibitive, but I think I will definitely play around with it when I get more fluent in Solidworks.

Good chance I will look into a larger 4-wheel design with fully inclosed wheels that has a bit more ground clearance then this design where the wheels will almost be like on stilts, kinda like Aptera's rearwheel except for all 4.

Blue Bomber Man,did you ever see a photo of the 3-wheeler that Doug Maleweicki (sp?) was putting together for his "One tank across America" attempt? It's pretty tasty and exhibits a creative front end with very low cross-section to enclose suspension/steering/wheels.It's worth a look.

Blue Bomber Man 03-17-2009 07:00 PM

I'll look it up =)

Cd 03-17-2009 09:39 PM

Blue Bomber Man, you are of course aware of all of the free open-source CFD software out there aren't you ? "thumbs-up"

( I'm not good with math, so I just do 3D modeling.)

Blue Bomber Man 03-18-2009 04:18 AM

Actually I am not aware of any program that will take a 3d cad program file and do a CFD analysis, but I would love to learn of some, thanks!

RobertSmalls 03-24-2009 10:58 PM

1 Attachment(s)
Quote:

Originally Posted by Cd (Post 93063)
Blue Bomber Man, you are of course aware of all of the free open-source CFD software out there aren't you ? "thumbs-up"

( I'm not good with math, so I just do 3D modeling.)

Yes, do tell us about the free CFD software. I've been utterly unable to find any.

I whipped up the attached in SolidWorks today. It needs fewer lines and more radiused edges, and then there are aerodynamically important complexities such as a radiator, suspension, &c. Without a radiator and a full engine bay, how will I know whether to build a variable-geometry grille?

I don't have FlowWorks, but I would love to run several models through the CFD analysis: the attached model, three with nose-cones of three different heights, and one with a boat-tail. That would determine how effective these aero add-ons would be, and whether to try to send air over the car or under it.

I'd be happy to make my .SLDPRT files available in the public domain. Anyone know of a good, free .SLDPRT of an engine, radiator, or maybe even a sophisticated model of a car?

RobertSmalls

Cd 03-24-2009 11:25 PM

Robert,. have you Googled "open source CFD software" ?
There is quite a selection .

RobertSmalls 03-28-2009 11:08 PM

Hmm, I see that there is. Can anyone recommend an easy-to-use one that I can feed a SolidWorks or Pro/E CAD drawing into?

RichardB 05-10-2011 05:40 AM

Quote:

Originally Posted by big_dave (Post 93019)
I've got solidworks and floworks, I'll do the calculations if you want.

I should add I am a beginner, so if you let me know exactly what you need doing I'll be happy to give it a go.

Dave do you still have access to flowworks, I have an autocad of my car and would like to know how it performs in flowworks.

big_dave 05-10-2011 07:52 AM

If you can create a 3D model in Solidworks from your Autocad then I'll see if I can run it through the analysis. It's been a while since I used it :)

Whattodo 11-17-2011 05:59 PM

Quote:

Originally Posted by big_dave (Post 237303)
If you can create a 3D model in Solidworks from your Autocad then I'll see if I can run it through the analysis. It's been a while since I used it :)

Exactly. And nothing changed since you used it last time :)

big_dave 11-18-2011 07:21 AM

Quote:

Originally Posted by Whattodo (Post 270797)
Exactly. And nothing changed since you used it last time :)

Huh?


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