Calculate curve Cl-alpha, Cd-alpha, Cm-alpha

[domenica...@fastwebnet.it]

Hello! I'm a newbie in fluent and I need help...I've tried to have a
look to the fluent guide but I haven't found a correct answer...the
problem is that I have a non convencional airfoil to analyze. Is the
section of a bridge and I have to calculate the curves Cl-alpha, Cd-
alpha, Cm-alpha for an aeroelasticity analysis. I have done the mesh
with gambit but I don't know how to set-up fluent for my analys. There
is someone can help me... many thanks to all peoples.

[Ankit Somani]

Hi Domenica,

Thanks for contacting us and we'll try our best to help you out.
Well the question you've asked in pretty broad and there are a bunch of things one has to do. I can give you a headstart:
1. Read case files through File --> read
2. Setup energy, viscosity, steady/unsteady using Define --> Models
3. Setup Materials (like for you, outside air and airfoil maybe aluminum, you can even make new materials) Define --> Materials
4. Define--> Boundary conditions (you must have set it to something in Gambit...now you can quantify it)
5. Solve-->Controls-->Solution for setting up various discretization schemes and algorithms for solving Flow, Turbulence and Energy equations
6. Solve-->Monitors-->Residuals for setting up convergence limits and plotting convergence parameters
7. Solve-->Initialize-->Initialize for initializing the flow field with parameters you want and starting solution procedure
8. Solve-->Iterate to set up no. of iterations/reporting intervals and actually starting the iterations.

This is just the general structure. You might have to alter it according to your needs. Also, now you can easily refer to fluent help files dealing with these tabs. If you have more questions, do contact us. We have a great set of students who have been working on Fluent for a while and I am sure they will be glad to help,

Best,
Ankit

--
Ankit Somani
Graduate Student,
Center for Energy Efficient Thermal Management (CEETHERM),
Department of Mechanical Engineering,
Georgia Institute of Technology
Voice: 404-731-7284

[domenica...@fastwebnet.it]

Thank you ankit.I've found a little tutorial for airfoil problem and
thank's to your help too, I'm starting to do something.
I've set material, boundary condition, segregated solution cell-based,
k-epsilon model for viscosity. But now I've got other problems..I have
calculate lift and drag for low angles of attack, but at 5° my
solution don't converge. I think I'm near the stall angle. Anybody
knows how can I do and how to set-up fluent in this case??
Many many thanks to all!!

> On Fri, Sep 5, 2008 at 5:55 AM, domenica.furi...@fastwebnet.it <

[its me]

Greetings

 

i am BSC CHEMICAL ENGG. graduate. and completed MS in process engg recently.  i want to take up higher studies in austria, uk , new zealand for phd program in cfd field. if any one guide to which university i can aplly through internet easily .. can any one can give any contact of supervisors in this field

 

Maria Mustafa

research scholar

NESCOM,

pakistan

 

[Ankit Somani]

Domenica,

Glad to hear that my advise actually helped!

I haven't worked on the airfoil problem personally, but if you haven't reached a converged solution and you don't think it's the stall angle, here's what I would have done.

In controls, solution - there are different discretization schemes present. Try to start with first order in momentum initially and then go to second order later. Also, try to play with the under-relaxation parameters. I have encountered issues of no-convergence. In those cases, giving a lower value for momentum factor and TKE factor helped me, though it took more time to converge. I am sure there are others out there who must have faced this issue, so you might get some tips on the internet.

Best,

Ankit