Vectors in animated transient simulation

[Anonymous]

 Hi everybody, 

me and my diploma mate are working on an evaluation of Autodesk CFD. At the moment we are up to a transient simulation of an safety valve.

everything works fine (more or less) but the problem is that we can't visualize the vectors at the origin-position of the valve. (as shown on the picture below). 

Does somebody know the solution for this problem or is this a known bug? 

Thanks a lot. 

Albin Kröll, Vienna

[matt.bemis]

Hi @Anonymous,

Thanks for reaching out to us on the forums! Have you tried tightening the grid spacing of the vectors? Perhaps you can't see vectors because the magnitude of the velocity is so small it does not meet the vector criteria. I took a screenshot of of the vector control and attached it here. 

Maybe you can fill in the plane and show me the magnitude and range of values we are seeing. 

Thanks,

[Anonymous]

Hi Thanks for your reply. 

I tried to maximize the vector density but i guess this is not the solution. Please have a look at the picture attached. Where the origin of the moving part is, are no vectors. 

[Jon.Wilde · Accepted solution]

Start this model with the valve outside of the model (move it in CAD along it's axis of motion).

Then in CFD use the 'initial position' option to move it into place. This will actually mesh the model BEFORE moving the valve, which is better for the mesh.

Also, with this you can enable the boundary layer/mesh enhancement, usually off by default in motion analyses so there is a double win here 🙂

Hope that helps you out 🙂

Jon

[Anonymous]

Thanks Jon, 

your solution worked. I made a new assembly with a by 100mm displaced valve and made a new analysis. 

Only difference in modell-settings is the start position of the moving part set to -100 mm and the minimum linit set to -100 aswell. 

Thanks again. Good service!!

[Jon.Wilde]

Hi,

That is great, thanks for the update!

I would just add - the minimum limit should be zero as it will refer to the point where you moved the valve to already.

(Or the maximum limit, depends which way is which 😉 )