## Drag coefficient simulation in ANSYS 12.0 Fluent

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jhthoh
0
Joined: Sun Feb 20, 2011 8:12 am

### Drag coefficient simulation in ANSYS 12.0 Fluent

Hello guys,

Somebody can give me some information about calculate the drag force and downforce with fluent software?

Actually, I'm taking final year project with design aerodynamic body for SEM race car. Now, I already completed mesh my model in ANSYS CFX mesh but i really don't have idea how to get the drag coefficient and lift coefficient with fluent. Can you guys help me?

Sorry for my broken English and disturbing. Thanks you in million...

PlatinumZealot
247
Joined: Thu Jun 12, 2008 2:45 am

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

"Raindrops .. drop top!"

PNSD
4
Joined: Mon Apr 03, 2006 5:10 pm

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

Not familiar with Fluent 12 but with 6.3 you could setup a force monitor to plot and write the Cd and Cl. Once the solution has converged it will give you a final answer (I persume RANS?). Providing your input reference values are correct then the values should be correct.

Is this your first attempt at CFD? If so then i advice the CFD-Online forums for any other assistance. Great

A quick google search bought this, hopefully helps.

http://www.cfd-online.com/Forums/fluent ... luent.html

n_anirudh
26
Joined: Fri Jul 25, 2008 1:43 am

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

FLUENT 6.3 and 12 are the same except for the GUI. Google is ur best friend

jhthoh
0
Joined: Sun Feb 20, 2011 8:12 am

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

PNSD, after i mesh in CFX mesh n import to Fluent, the whole domain become 1 "wall-air", i can only separate them and just define them.but as for gambit, we can directly define it after mesh before import to fluent.will tis affect??
and how about the reference values?i jz use its default or i need to change them?lk the area,length,viscosity,etccc..
i am new in this so i duno many things.

PNSD
4
Joined: Mon Apr 03, 2006 5:10 pm

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

Not used CFX before, but can you not define boundary conditions in CFX? If not then I advise gambit and set your boundary conditions that way, (inlet, outlet, walls, etc) then import into Fluent.

For the reference values, you will have to set the area, length and depth. I believe the other values will be defined when you chose where to compute from... So do not change any of the others.

If you are new to Fluent then I would recommend you follow through the tutorials made available by Cornell University.

https://confluence.cornell.edu/display/ ... ng+Modules

These are a great help and will introduce you to many of the common functions you will need to use for most simulations.

Likewise, what is your knowledge of the problem you are trying to simulate like? A must have requirement before any of this would be a strong background knowledge of fluid dynamics/aerodynamics and the problem, otherwise you are going to be producing some very pretty pictures with very little meaning. I suppose being an final year student you should have sufficient knowledge to be able to read and describe the flow patterns you see.

Is it a 2d or 3d case? I would assume 3d if you have used CFX to mesh?

jhthoh
0
Joined: Sun Feb 20, 2011 8:12 am

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

I not very clear of this.i just need to simulate the flow around a car body to get its drag coefficient.i now trying to mesh using gambit.Simulate is 3d..Anyway,i not expect to do a very fine result since i am new in this and i have short time constraint.

PNSD
4
Joined: Mon Apr 03, 2006 5:10 pm

### Re: Drag coefficient simulation in ANSYS 12.0 Fluent

Okay, well using Gambit you can define the Boundary types, then once in fluent, with a solved solutiuon with appropriate boundary conditions you should be able to obtain the Cd how ive mentioned above.