CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums

Search Results

Register Blogs Community New Posts Updated Threads Search

Showing results 1 to 16 of 16
Search took 0.00 seconds. Search: Posts Made By: vega
Forum: OpenFOAM Running, Solving & CFD September 20, 2007, 10:57
Replies: 98
Views: 17,838
Posted By vega
Hi Rosario, I agree that lo

Hi Rosario,

I agree that locally there may be negative turbulence force in the separated flow region.
But for 12.5 deg Ahmed body, flow remains attached.
And even if it separates, only part...
Forum: OpenFOAM Running, Solving & CFD September 19, 2007, 11:42
Replies: 98
Views: 17,838
Posted By vega
Rosario, My liftDrag utilit

Rosario,

My liftDrag utility does not have turbulent drag part as yet so I am not getting this magnitude.
I was focusing on the pressure drag only. I know from experience and literature that...
Forum: OpenFOAM Running, Solving & CFD September 19, 2007, 09:44
Replies: 98
Views: 17,838
Posted By vega
Rosario, You are getting mu

Rosario,

You are getting much lower numbers than me for the same mesh. One difference I see is the initial solution. I start from velocity field of (0 0 0)
as opposed to (60 0 0) for you. I...
Forum: OpenFOAM Running, Solving & CFD September 18, 2007, 16:18
Replies: 98
Views: 17,838
Posted By vega
A good news I guess Fluent si

A good news I guess
Fluent simulation for the same mesh (0.63 Mill Cells) as used for OpenFoam predicts Cd of 0.309.
Now OF results do not look that bad. Fluent model
of ~3 Mill cells gives...
Forum: OpenFOAM Running, Solving & CFD September 18, 2007, 00:00
Replies: 98
Views: 17,838
Posted By vega
Yes, confirmed I was using are

Yes, confirmed I was using area of the full model.
So Sorry for the confusion.

By changing to second order schemes, Pressure Cd does come down to 0.320 (with correct area) but it is still...
Forum: OpenFOAM Running, Solving & CFD September 17, 2007, 09:33
Replies: 98
Views: 17,838
Posted By vega
Vincent, Its quite possible

Vincent,

Its quite possible that I am using area for the
full body. We have to use the half model frontal area, exactly as you mentioned. I will check it from home tonight and let you know
...
Forum: OpenFOAM Running, Solving & CFD September 13, 2007, 23:13
Replies: 98
Views: 17,838
Posted By vega
Rosario, Initially I had pi

Rosario,

Initially I had picked values corresponding to the turbulence intensity of 0.6 and length scale of 0.02. It gives k and eps of order of 0.1. After that I played with several other...
Forum: OpenFOAM Running, Solving & CFD September 12, 2007, 19:54
Replies: 98
Views: 17,838
Posted By vega
BastiL, I had better succes

BastiL,

I had better success with GAMG solver for pressure. See it in the setup files I posted in this thread.
Also, see if your initial k and eps values are reasonable
--
R
Forum: OpenFOAM Running, Solving & CFD September 11, 2007, 23:55
Replies: 98
Views: 17,838
Posted By vega
Vincent, BastiL, I just sen

Vincent, BastiL,

I just sent you the whole model via yousendit.com.
Just go to the link that you will get on email accounts in the profile and download the file.

thanks

--
Rajneesh
Forum: OpenFOAM Running, Solving & CFD September 11, 2007, 23:42
Replies: 98
Views: 17,838
Posted By vega
Vincent, BastiL, I have not

Vincent, BastiL,

I have not been able to upload the whole Ahmad mesh model to my googlepage site. Its about 20Mb after gzipping. I am not sure if uploading such a huge file to this forum is...
Forum: OpenFOAM Running, Solving & CFD September 7, 2007, 16:26
Replies: 98
Views: 17,838
Posted By vega
Srini, As far as I could fi

Srini,

As far as I could figure out from liftDrag.C,
viscous drag is computed separately from
laminar and turbulent viscosity. I am not getting the contributions from the turbulent...
Forum: OpenFOAM Running, Solving & CFD September 7, 2007, 00:02
Replies: 98
Views: 17,838
Posted By vega
looks like contribution from t

looks like contribution from the turbulence are not
added to the viscous drag. I think I need
to compute turbDragCoefficient as well. If this correct, can anyone please explain the first ...
Forum: OpenFOAM Running, Solving & CFD September 6, 2007, 23:34
Replies: 98
Views: 17,838
Posted By vega
12.5 Deg Half model results wi

12.5 Deg Half model results with openFoam (model size ~0.6 Mill)

Pressure Drag: 0.189
Viscous Drag: 0.006!!

Pressure drag is very close to the experimental numbers and the Fluent's...
Forum: OpenFOAM Running, Solving & CFD September 5, 2007, 22:01
Replies: 98
Views: 17,838
Posted By vega
I use Fluent/Tgrid/Ansa at my

I use Fluent/Tgrid/Ansa at my work for CFD simulations.

I have used Tgrid ( Prism layers on body + Tetra) to create symmetric half and full models of Ahmed body of 12.5 and 30 deg. I came...
Forum: OpenFOAM Running, Solving & CFD August 24, 2007, 10:34
Replies: 98
Views: 17,838
Posted By vega
I have been using Fluent for r

I have been using Fluent for racing car (NASCAR) applications for past several years. Steady state RANS solver (simpleFoam type algorithm) seems to give reasonable predictions for drag. Lift is not...
Forum: OpenFOAM Running, Solving & CFD August 10, 2007, 09:10
Replies: 98
Views: 17,838
Posted By vega
Vincent, A very good referenc

Vincent,
A very good reference for Automotive Aerodyanmics is:
Aerodynamics of Road Vehicles, by W. Hucho
Showing results 1 to 16 of 16

 
Forum Jump

All times are GMT -4. The time now is 07:07.

Contact Us - CFD Online - Privacy Statement - Top