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 Giuseppe January 19, 2006 06:19

Dynamic mesh, wall motion

Hello to all, how can I define the wall motion, h(t)=Ho*sin(omegat)? I have to use UDF or profile in dynamic mesh? I'm studying the behaviour of a bridge section (great belt east bridge) and I have to analyze the formation of vortex shedding in both cases of fixed section and moving section, immersed in a bidimensional unsteady flow. Please help me, thank you

 Luca January 19, 2006 09:26

Re: Dynamic mesh, wall motion

Ciao Giuseppe! You should use a UDF for the dynamic mesh model. I think the DEFINE_GC_MOTION could be what you need. Luca

 Giuseppe January 19, 2006 12:47

Re: Dynamic mesh, wall motion

Grazie Luca! Do you have an example of this kind of UDF? Can you send me it? Are you the ing. with which I spoke the past time?

 Luca January 19, 2006 12:54

Re: Dynamic mesh, wall motion

Yes Giuseppe, here I am! No unfortunately I have no example to give you but you should look at the manual. The example you find is all you have to do to set the cg motion. Luca

 Giuseppe January 19, 2006 13:30

Re: Dynamic mesh, wall motion

thanks any way, see you later

 J. Kim January 19, 2006 14:56

Re: Dynamic mesh, wall motion

Giuseppe,

You are going to do what I want to do. I hope to share experiences together.

Have you ever tried simulation for a fixed bridge? If yes, what about the results such as Cd, Cl, Strouhal number ...? My results (using k-e, RSM and 2-dimensional steady, unsteady) were not close to the experimental data.

 Giuseppe January 20, 2006 04:25

Re: Dynamic mesh, wall motion

Hello Kim, firstly, I have to simulate the flow past a circular cylinder to optimize my calculate; secondly, I have to simulate the Great Bealt Est Bridge section. For comparison, can you tell me which parameters you have set in your problem? Solver, Material, Re, boundary conditions, Control solution, etc. In addition, how can i check the convergence through the residual plot?

 J. Kim January 20, 2006 09:26

Re: Dynamic mesh, wall motion

I used a model scale and compared CFD results with other experiment and numerical analysis data in terms of mean drag coefficient, fluctuating (i.e. root mean square (RMS)) lift coefficient, Strouhal number.

For solver, 2nd order in spatial and temporal discretization. Unsteady. Segregated. SIMPLE, etc. For material, air was used. Rectanguler shape computational boundary was used. For inlet boundary : inlet velocity; outlet boundary:pressure outlet. Upper and bottom boundaries:symmetry boundary conditions were employed.

 Giuseppe January 20, 2006 11:00

Re: Dynamic mesh, wall motion

Do you have used Gambit like prepocessor? Whit which experiment and numerical analysis do you have compared your simulation? Firstly, i have studied a tutorial about a cylinder cross by a bidimensional flow? Do you want it? Which is the geometry of your section?

 J. Kim January 20, 2006 12:02

Re: Dynamic mesh, wall motion

You may have experimental and numerical results by searching Google just typing in "Grate Belt East Bridge". And papers were published in the Journal of Wind Engineering and Industrial Aerodynamics.

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