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Old 12-14-2019, 11:54 PM   #21 (permalink)
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Originally Posted by aerohead View Post
I believe that at 70-mph,a 10% reduction in Cd produces a 6% increase in mpg.I apologize if I screwed that up.
Fixed

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Originally Posted by teoman View Post
Check out the software that freebeard linked a couple of months back. Appears to be slightly more capable that the Autodesk stuff.
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The key to low-compute-power CFD IMHO is OpenVDB:

It's all about the sparse inverted B-trees, if ya know what I mean. And being able to attach arbitrary attributes to each voxel. If you need it, the odor of hickory smoke.
Instead of computing every voxel in the virtual wind tunnel, it looks more diligently closer to the aeroform.

It's above my pay grade.
I'm not sure I am following on that. Is this a modelling and CFD or? Open source is usually free right?

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Holy moly!

They let you ride around in that? Gotta love the USA.
I've had 2 cops follow me (both from a small town on seperate occasions) neither one pulled me over. I did research regarding it and aside from small stuff (no reflectors in the rear sides) it is legal. There isn't any inspection here, but the bumper and other crash related stuff is still there it's just covered up.

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At 55 mph, a 10% drag reduction translates to a 5% increase in fuel economy. At 70mph,a 10% drag reduction translates into a 6% increase -Phil Knox (Aerohead), Aerodynamics Seminar #2
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My other hobbies have no ROI (making things go fast). So I'm having fun modding my car for better mileage and the side effect is that I save money on gas day to day.
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Old 12-15-2019, 01:43 AM   #22 (permalink)
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You've added a crumple zone. Worst case and heaven forfend, but if you're rear-ended the fool behind you will be safer.

You should strongly consider the old thread from 2013, Military theme for fun ...and function

Bumblebee stripes and some cryptic Zombie Response Vehicle markings would not be out of place.

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I'm not sure I am following on that. Is this a modelling and CFD or? Open source is usually free right?
Well.... It's a deep subject.

That kind of work involves a tool-chain. OpenVDB is a visual database. It can be queried by anything that can structure a query. It's currently employed by the movie industry, Maya and (apparently*) Blender.

I took a deep dive into the [pseudo]code structure a few years back. I recognized a lot of it from when I was trained to edit Mac OS HFS structures (I worked for Symantec for 9 years). B-trees allow you to get to any point in the point cloud in a discrete number of steps. Shallow trees have fewer steps to get to an arbitrary point.

There was a brilliant way of encoding things like pressure or a motion vector for each point but I don't recall and prolly couldn't explain if I did.

So there's that. I'm like a scarecrow in a field pointing thataway.


*I struggle with Blender itself, let alone where the API for the C++ libraries are. Have you looked at Blender? I'm not doing any render farming on my laptop.
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Old 12-18-2019, 11:03 AM   #23 (permalink)
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Gurney flap

So far,no really low drag car has used a Gurney flap as a palliative for flow separation.Hucho and the others,who've explored really minimum drag all recommend that we stay on the streamlined contour,then if length is an issue,just chop the body as Koenig-Kamm did at the FKFS,next door to Daimler-Benz.
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Old 12-18-2019, 01:25 PM   #24 (permalink)
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The Gurney flap aka wickerbill was a field expedient. As was the Gurney Bubble.


https://www.gt40s.com/media/mkiv-gurney-bubble.901/
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Old 03-04-2020, 05:54 PM   #25 (permalink)
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I came across something and this thread seems most relevant:


This speaks to the integration of OpenVDB with Blender. It is about importing data sets into the program, where for CFD the internal physics engine would be used to generate the data.

But it shows that the future isn't quite here yet.

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