[timastrop]

Hello all,

Preface - I'm not an engineer, I'm a palaeontologist. Basically I have 3D scans of fossils I want to simulate water flow past to calculate drag coefficient and torque. I had some success using autodesk but due to licencing issues I've had to switch software and am learning ansys.

What I need to do is find a way of getting my scans to work in fluent. They exist as .stl files but i have managed to covert to .stp using freecad. however, i need top create a 'domain' (box) around the models in which to simulate flow. All help and tutorials online use the inbuilt primitive shapes like spheres and do not explain how to use your own models.

I'm very desperate to get these simulations working asap and would be extremely grateful for any help

Cheers

[cryabroad]

Hi,

I think you are on the right track. If you want to simulate the flow around an object, what you can do is, build a large block (e.g a rectangle in 2D), and then introduce your object into the block and cut it out.

In this way you obtain a flow field around the object. Keep in mind that the block has to be large enough so that the boundary conditions are very easy to set up. There are many tutorials on Youtube, for example this one, https://www.youtube.com/watch?v=DXWO-X16UIo

Hopefully this helps!

[timastrop]

Thanks for the reply!

What I've done is get my .msh into designmodeler and used the enclose tool to get it in a box. I've meshed and assigned inlet/outlet and can run a simple flow in FLUENT (woo!), however, i need to report drag/lift etc on the fossil model but cannot as it is not a 'wall'? Any idea how to fix that?

Cheers

[cryabroad]

I think in the drag monitor you can select one of the wall zones (which represents the outer profile of your fossil, remember that the fossil itself has been removed from domain as Fluent only calculates the flow field) and Fluent will calculate the drag coefficient on it.

The attached figure is what I found in the users' guide and the highlighted options shows what have been selected when calculating drag. You can see that Fluent does calculate drag on "wall" region.