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Old 12-30-2020, 02:06 PM   #1 (permalink)
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$ 53,900 (US) for CFD?

1) I read through a paper on Tesla Model S CFD analysis out of China.
2) They mentioned:
* a 120-core server.
* kappa-epsilon turbulence model
* and SIEMENS STAR-CCM+ software
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Online, DELL Computer is offering a 120-core, 512-Gb unit for $ 4,000 ( US )
............................................... a 120-core, 1-Tb unit for $ 6,000 ( US )
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The Kappa-Epsilon turbulence model is available, free, online.
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It looks like, you can't get a direct price from SIEMENS, without going through a salesperson. ( It was the same for Dassault's Exa POWERFLOW ).
I did find an invoice online, from the US Nuclear Regulatory Commission, which purchased the STAR-CCM+ for $ 49,900 (US).
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Another fly in the ointment is, that one must have the data cloud for any specific vehicle, to input into the program.
The Chinese investigators had a Tesla, which was laser-scanned to create the data cloud.
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A single iteration required 3-hours, 25-minutes run time.
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Any modification of interest would require its own additional data cloud.
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The computer sounds cheap. One hour at Haus Racing's moving floor tunnel would pay for the small DELL computer.
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With something like 36,000 EcoModder members, we might swing enough donations for the software. A cheap cup of coffee per member.

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Old 12-30-2020, 03:37 PM   #2 (permalink)
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I've got a spare Dell R740 and Tesla P100 GPU laying around. Don't mind the power consumption currently as we need the heat anyhow.

Apparently I'm a Siemens employee now. Employee pricing?
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Old 12-30-2020, 04:58 PM   #3 (permalink)
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Interesting... There is an online CFD forum.

https://www.cfd-online.com/Wiki/K-epsilon_models

One can acquire a point cloud with a smart phone. A render-farm of ARM Cortex-A72 4-core compute modules would be $30 x (120/4) = $900 plus supporting hardware.

Quote:
A high-end i7 processor has a maximum TDP (Thermal Design Power) of 130 watts. The average ARM-based chip uses just two watts max budget for the multi-core CPU cluster, two watts for the GPU and maybe 0.5 watts for the MMU and the rest of the SoC!
http://www.androidauthority.com/arms...ent-processing
Admittedly, the DELL system probably has loaded-up PCI-e slots. But having the RAM distributed over the SOCs has to reduce latency, no?

Quote:
With something like 36,000 EcoModder members, we might swing enough donations for the software. A cheap cup of coffee per member.
If the Smartmatic/Dominion kerfluffle has taught us anything, it's the importance of Free and Open Source software.

https://en.wikipedia.org/wiki/Simcenter_STAR-CCM%2B sez there exists a Linux version. I can find mention of the COMOS site licensing mechanism, but I haven't dug deeper, it's too sunny outside.

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Old 12-30-2020, 05:47 PM   #4 (permalink)
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Aerohead. I was told you only ever advise people to use your template. You are blowing my mind. It's almost like someone is trying to spread misinformation on this site. You should really advise people that ten surface pressure readings will suffice to establish whether a mod has lowered drag. That's where the real money is.


Disclaimer: This post is meant to be humorous, however, it will probably fail at it's stated goal. If you have no sense of humour please disregard.
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Old 12-30-2020, 05:56 PM   #5 (permalink)
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readings

Quote:
Originally Posted by orange4boy View Post
Aerohead. I was told you only ever advise people to use your template. You are blowing my mind. It's almost like someone is trying to spread misinformation on this site. You should really advise people that ten surface pressure readings will suffice to establish whether a mod has lowered drag. That's where the real money is.


Disclaimer: This post is meant to be humorous, however, it will probably fail at it's stated goal. If you have no sense of humour please disregard.
There's a research paper online about the Mitsubishi Lancer Evo and VGs. They executed hundreds of pressure readings on the boot alone! Real high-resolution. A nice scientific benchmark.
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Old 12-30-2020, 07:08 PM   #6 (permalink)
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https://www.cfd-online.com/Wiki/Best...automotive_CFD

Quote:
Best practice guidelines for automotive CFD
This article is a stub, a short article which needs to be improved. You can help by expanding it.
A fertile field waiting to be sown.

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If you were to ask ten different people what Open Source Software (OSS) is, you would most likely get ten different answers. The official definition can be found, from The Open Source Initiative, along with guidelines and information related to an Open Source license. From an engineer's standpoint: "Open-source software ... is computer software that is ... provided under a software license that permits users to study, change, and improve the software."
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Old 12-30-2020, 08:56 PM   #7 (permalink)
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Watched a fascinating video on the development of CFD, its limitations and potential. Warning. There are depictions of a lot of transonic studies of NACA wing template 0012. NoT aNoTheR TemPlaTE!!!1!

Its from 2014 so not up to date but interesting, nonetheless.

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Old 12-31-2020, 12:25 AM   #8 (permalink)
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His conclusion is the same point I made in another thread, Moore's Law isn't enough to bridge the mesoscale gap.

Have you looked into OpenVDB?
Quote:
OpenVDB is an open source software library for working with sparse volumetric data. It provides a hierarchical data structure and related functions to help with calculating volumetric effects in CGI applications. Volumetric effects apply to volumes, as opposed to just on surfaces. An example is fog.

Specifically catering for feature film production, the library was originally developed by DreamWorks Animation and is currently maintained by the Academy Software Foundation (ASWF). The primary authors are Ken Museth, Peter Cucka, Mihai Aldén and David Hill. OpenVDB is written in C++ and has Python bindings.

OpenVDB is supported in a wide range of CGI software, such as Blender (since April 2016), Cinema 4D, Houdini and RenderMan. It was used in the films Puss in Boots (2011) and Rise of the Guardians (2012).
"sparse volumetric data... a hierarchical data structure and related functions" It's brilliant under the hood a sparse, shallow inverted B-tree structure and each data point can carry attributes like pressure, temperature, momentum & etc.

Blender has OpenVDB and a physics engine. I struggle with just the modeling, but all the animation rigging, rendering and video compositing needed are in there.

Quote:
Originally Posted by DDG
How to Import and Shade OpenVDB Simulations in Blender ...
https://www.blendernation.com/2020/1...ns-in-blender/
OpenVDB is a file format to store volumetric data like fire and smoke, clouds or water simulations. In this video I demonstrate how to use them in Blender by importing and shading an explosion. The file used in the video can be downloaded for free, if you want to follow along.
....meanwhile, I'm needing to figure out how to update Blender from 2.79 to 2.91 on my ARM system. I figured out the array modifier — you have to rotate an empty (obviously )
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Old 12-31-2020, 12:47 AM   #9 (permalink)
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No one has mentioned OpenFOAM?

I know nothing about CFD (except that I see a huge amount of amateur stuff on the web that is obviously quite wrong eg in calculated Cd figures) but I know of an aerodynamicist using a professional(?) version of OpenFOAM.

Maybe I'm just dumb, but no one has quite explained how you develop the shape of your car to model in CFD - 3D scanning?

OpenFoam is here.
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Old 12-31-2020, 02:07 AM   #10 (permalink)
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Sorry. I didn't go that deep in the prior post OpenFOAM appears here in the CFD Wiki:

https://www.cfd-online.com/Wiki/What...nFOAM_.28OF.29

The pipeline from image capture to usable model involves re-topologizing. An example.


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