CFD - Computational Fluid Dynamics, Motorsport, Formula 1

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.
sixfor
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Joined: 03 Jul 2011, 13:00

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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hello everyone, i'm new to cfd, my lecturer gave me one assignment to analyze drag on a car, he gave me the geometry without mesh, however when i want to mesh it, my gambit keep saying error which i couldnt identify it, can someone help me in finding the error for my geometry

thanks and regards
asyroff

PNSD
3
Joined: 03 Apr 2006, 18:10

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Does the geometry import into Gambit ok? Or is there any other issue with the geometry whilst in Gambit?

edit - if you could provide more details it might help.

sixfor
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Joined: 03 Jul 2011, 13:00

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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PNSD wrote:Does the geometry import into Gambit ok? Or is there any other issue with the geometry whilst in Gambit?

edit - if you could provide more details it might help.
yes everything is ok, but when i try create mesh it keep saying error

PNSD
3
Joined: 03 Apr 2006, 18:10

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Copy and paste the log here on the forum.

Gambit posts a log of activities at the bottom, copy and paste whatever the error says here :).

Have you got as far as having the edges meshed where each edge has your desired number of nodes? Meshed the faces? Is it the volume meshing which is the issue?

FuzzyDice
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Joined: 23 Jun 2007, 01:26

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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hello

i made a simple 2d geometry in catia and meshed it. and i also made 1D coat mesh of one side of my geometry. i did this so i can do my grid separation more easily. if i dont do it fluent will by default separate the hole side of my geometry into one zone. thats not good since i need one part of that side to be defined as axis and other as wall.

but when i import my mesh into fluent it doesnt read the 1D coated mesh as a separate zone.

Any idea?
Thanks

FuzzyDice
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Joined: 23 Jun 2007, 01:26

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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i found the solution

nash85
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Joined: 15 Aug 2011, 08:02

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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arjun.yadav

I'm interested to know why are you running 3.6 billion cells on only 670 cores? Thats 5 million per core. Whats your Reynolds number? I would guess that a DNS of a golf ball would take months to run using that many cores. Btw, which HPC facility are you using?

Cheers

Neil

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Tozza Mazza
1
Joined: 13 Jan 2011, 12:00
Location: UK

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Hi everyone,
Me and a design colleague are in the process of designing an F1 car (viewtopic.php?f=6&t=10242) for 2012, and are getting to the sharp end of proceedings. Very soon we hope to have both our front wing and rear wing finished and already have a base diffuser, as well as a large portion of the car already done.

The aim of the project is to, with the aid of CFD technology, meaningfully update the car and test out new ideas and innovations to see if they're worth including on the car.

However, neither me or my colleague have access to CFD technology, although both of us would like to learn about it!

We were wondering if somebody on the forum would like to help us! We basically need someone to run the car for us, give us some DF and Drag figures, and suggest areas of improvements, give feedback, and test future updates.

We are sure this would be enjoyable for both parties and boost all involved's knowledge of F1 aerodynamics, something I personally am hoping to go to University next year to try and study (Aeronautical Engineering).

I'm sure i can find a way of getting the files into a valid format!
Many thanks for reading!

PNSD
3
Joined: 03 Apr 2006, 18:10

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Ive said it a million times if you want meaningful results then you need to make the models far simpler than what they currently are.

Unless a user has access to some sort of supercomputer grid then you will not have enough mesh resolution due to the detail. The results will just be pretty pictures.

Meshing something as complex as that model you link would be a nightmare for anyone.

arjun.yadav
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Joined: 04 May 2010, 10:10

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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nash85 wrote:arjun.yadav

I'm interested to know why are you running 3.6 billion cells on only 670 cores? Thats 5 million per core. Whats your Reynolds number? I would guess that a DNS of a golf ball would take months to run using that many cores. Btw, which HPC facility are you using?

Cheers

Neil

sorry for late reply, did not visit site in between.

I used 600 cores for 3billion (the last calculation). And my calculation time for 5000 time steps is roughly 15 days. I am using SIMPLE algorithm so no courant number dependency.

Some of the results will be presented on 7th september at Kobe , where the k super computer is. (I am using k-supercomputer).

Here are few interesting things about this solver and the reason I can use only 600 to 700 cores for it.

1. I have written a memory efficient code that uses minimum memory required so that i can run large cases. Specially written for these purposes.
2. I designed a special Poisson equation solver that could be used with SIMPLE algorithm. It is basically FFT based direct method adapted for non uniform poisson equation for pressure correction.
3. I designed a new all to all algorithm that is very efficient (0.3 seconds to redistribute this 3 billion cell data among processors) This means FFT based solver works like charm.

4. With 3 sub iterations I take roughly 300 seconds per time step. Because it is implicit algorithm I guess it is the most efficient algorithm (implicit + efficiency of direct solvers).


5. I wrote a post processor for creating iso-surfaces of Q criteria etc. so that I do not need to load all the data into paraview and can do post processing easily (animation will be presented at k comp on 7th sept).


Some of the things newly developed and patented for my company in the process:

1. O(3) 1 D search algorithm for linear search.
2. Moving solid bodies and marking of solid - fluid. A new algorithm that can do in 0.5 seconds for 1 billion of more mesh. This require 3D nearest neighbor search so is very difficult task to do otherwise. (uses 1)
2. A non uniform Poisson solver for pressure correction.


PS: I have http://www.inavier.com for unstructured grid solver.
I am working on a parallel version of this solver from point of view of doing very large calculations. I learned a lot from this large calculation, so I am hoping to put all that into this version. I have parallel matrix solver running now. And i have designed a very efficient GGI interface algorithm too. Actually parallel version of inavier for navier stokes is also working now but i am going to rewrite the whole thing.
So just wait for 3-4 months, we will have a unstructured grid solver that will be designed for large calculations (100million or more).

eschezal
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Joined: 19 Sep 2011, 21:19

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Hello
I am engineer and i need make the final project. I want apply cfd in a f1 parts ¿some idea?. first, i need draws of the parts of the car. Thank you

tonster
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Joined: 30 Aug 2011, 15:55

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Tonn wrote:I am useing CFDesingn
Does anybody know how do turn off the Auto Stop?
I just keep geting that message: Time Average Values have flattened - Auto Stop
This may be a little late, you could have already figured this out by now. To turn the auto-convergence off, simply click solve, solution controls, advanced..., and un-check automatic-convergence assessment.

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KeithYoung
24
Joined: 02 Jul 2003, 20:21
Location: USA
Contact:

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Hey guys this is Keith (rough_wood) from the start of this thread. Is anyone currently doing any projects? I am near completing my Engineering curriculum and wondered if anyone had good enough ideas that I might be able to pull some wind tunnel time before I graduate.

I've gotten several emails over the years about my old website. Yes, it's down, and unfortunately no I don't have any of it saved.

Let me know who has software and knows how to use it.

aerorea
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Joined: 13 Dec 2011, 18:48

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Hey everyone,

I am newbie here.

I am absolutely blind, don't know anything about cfd and aerodynamics.

Would anybody here at least help me how to create simulation of air flow over cylinder such as below link using gambit 2.2.30 and fluent 6.2.16?

http://www.youtube.com/watch?v=Ukt_798SKrA

Thank you very much

A

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raymondu999
54
Joined: 04 Feb 2010, 07:31

Re: CFD - Computational Fluid Dynamics, Motorsport, Formula

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Hey folks. Just wondering. As we know from miserable ventures such as Wirth and Virgin, CFD is not bulletproof. As teams such as Ferrari have shown us too, you can have an almost "faulty" CFD with bad correlation. I assume that plugging in numbers from the cars' sensors would allow the CFD to assimilate these numbers, and improve its correlation. So what "baseline" is open source/amateur CFD working from, and how accurate is it really?
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