How to create a surface with 2 closed loops (like annular) from Geometry tools

[Anonymous]

I have solid volume from Inventor imported into CFD package. Now I want to create "fluid volume" using "Void Fill".

But I cannot select "Unclosed loop".

I know I cannot create a "surface" using "unclosed loop" usually.

but my case, I need to create a sort of "ANNULAR shape". 

In this case I need to select "2 closed loop" to create annular surface. 

But once I select either outer or inner closed loop then I cannot select the other one. 

How can I create a surface with 2 closed loops? like annular? 

[Jon.Wilde]

Hi,

Might I suggest you share an image of what you are running? I ask as it is highly likely you are far better off adding some fluid extensions in CAD to seal off the inner volume. CFD will fill it for you when you launch. You will then have the chance for better developed flow at the inlet and no recirculation over the outlet 🙂

[Anonymous]

Here is detailed description of my problem with figures

let's say I need to perform fluid flow for tube-in-tube heat exchanger.

I have two concentric tubes as shown.

one fluid flows through inner tube that is inner fluid, while outer fluid flows through annular area created two concentric tubes.

Now I imported this solid geometry into CFD package and need to create 2 fluid volumes using "Void Fill".

Creating inner fluid is straightforward. easy done. (second figure) 

the problem is creating outer fluid. outer fluid I need to create surface that contains "2 closed loops".

1. inner circumference of outer tube and 2. outer circumference of inner tube.

It is impossible to pick outer circumference of inner tube after I selected inner circumference of outer tube.

(In the third figure I cannot select Edge 6: which is outer circumference of inner tube)

So I have trouble to create fluid volume using Void Fill function when surface contains more than 2 closed loops.

If I neglect to pick Edge 6 (which is outer circumference of inner tube), I got OVERLAPPED volume as shown in the last figure.

created volume overlapped with inner tube and inner fluid volume.

How can I create a surface like annular in void fill???

[Anonymous]

here is the last figure.

[Jon.Wilde]

Yup - this is what I mean 🙂

Just add solid extrusions in CAD, which will also be fluid volumes in CFD. Make them 5x longer than their diameter at the inlet and 10x at the outlet, that should be perfect.

Bring through a sealed volume into CFD and it will automatically fill the void for you.