Learning Forum

[chasha19]

Hello,

I am new to AnSys. I am using AnSys 2020 R1. I am trying to simulate 1kg/s liquid water flow through a simple 90 degree 20mm OD 3mm wall thickness pipe elbow. 

If I import a step file that models this shape from solidworks as my geometry, I eventually run into a problem in the meshing process because I cannot seem to select the negative space of the pipe as the inlet or outlet, which eventually leads to me being unable to set inlet and outlet flow characteristics under boundary conditions in the setup process. The best I can do seems to be to select the inner diameter and set that to "inlet" like so (i realise this is incorrect):

The result of this, when in the setup process window, is that the boundary conditions listed are only "internal" and "wall", it does not include inlet and outlet which is what is needed.

The only way I can see to get around this is to import a solid rod instead of a pipe as my geometry, and name the entire inlet surface as inlet (and the same for outlet). This way when I'm in the setup process, I can toggle inlet and outlet flow characteristics and eventually run the calculation.

in other words instead of analysing an accurate model of the pipe, I've modelled the negative space of the pipe which is then analysed. Is this the correct way to do this analysis? can you analyse an actual pipe modelled accurately, or must you first create the plug / negative space model of the pipe to be able to analyse it's flow in AnSys?

Thanks

[Kalyan Goparaju]

Hello, 

What you eventually ended up doing is infact the correct way of going about performing fluid flow analysis, where no interaction (like heat transfer etc.) is involved between the pipe geometry and the fluid inside the pipe. In such cases, there is not need for the geometry to be present in the simulation and all that is required is the fluid volume. 

Thank you, 

Kalyan

[chasha19]

OK thank you. 

If I want to do external flow analysis around a body (a sphere, for example), how do I set inlet and outlet boundary conditions?

[Karthik Remella]

Hello,

You will need to create an enclosure region outside your geometry and subtract the object of interest. This new volume you obtain will be the fluid region. Then, you should be able to create your inlet. The boundaries obtained because of the object (sphere) will be your walls.

Thanks.

Karthik