Hi all,

I am looking for a UDF that calculates the integral of the pressure forces (resultant of lift and drag) for an incompressible flow past a cylinder in 2d. Then, via a certain differential equation -not known yet- the displacement of the cylinder's center of gravity will be calculated then fed to the solver to move the whole cylinder and the mesh consequently. That is supposed to be made in transient simulation of course. So, this UDF will be used in the moving mesh model so as the simulation works as a coupled fluid-structure interaction.

Now, could any body give a hand here?

Cheers, Amr

I think Fluent has one tutorial specific on this. Please check the FLUENT6.3 dynamic mesh tutorial.

Amr,

I am just wondering, hvae you solved your problem with the UDF. I am still struggling here. Hope you can share.

Thanks.

Hi Sham,

Well, I have been working on this issue since then. What I decided to do is to takle a simple 2D cylinder that would vibrate as a two degree of freedom rigid body. So, I would need a UDF (or after research, possibly a 6DOF fluent's UDF) that would integrate the forces on the cylinder, solve the equations of motion (in x and y coordinates) and update the CG location. Then, the mesh should be updated thru a adequate dynamic mesh mechanism that I suspect will be smoothing with remeshing.

Currently, I am stuck with writing this UDF since I would leave the modified 6DOF as a last resort.

Cheers, Amr

Amr,

I asked FLUENT support centre about free vibration and they replied to me mentioning something like you mention above. If you can give me your e mail, I can fwd that to you.

By the way, are you doing your phd on this? I hope we can work together. Hope to hear from you.

Sham.

Have sent you an email thru this website. Hope you received it.

Cheers,

Amr