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Tadiwos August 27, 2001 05:11

External flow
Hi Friends,

I am trying to modell an external flow, flow over a cyclist helmet. But on CFX 4.3, every example is done for internal flows, like pipe, and furnance models. I created the geometry file successfully, how can i drive air on tha helmet? Do you think CFX4.3 does not work for external flows???


Dan Williams August 28, 2001 01:11

Re: External flow
CFX-4 can certainly do external flows. What exactly is the problem you are having? i.e., you can't figure out how to set it up in CFX-4, the solver doesn't run and crashes, etc..?

John C. Chien August 28, 2001 03:07

Re: External flow
(1). If you are solving flow over a sphere, you would create a box, a sphere, and then generate the mesh between the sphere and the box boundary. This becomes your computational domain. (2). Then you can specify the inlet condition on the box boundary, the far-field boundary conditions on surrounding walls, and the exit condition on the downstream wall. On the sphere, you will have to specify the wall condition. That's all. (3). Now replace the sphere by your helmet model. The process is identical. (4). This also can be used for flow through a pipe, where the helmet has zero size (removed from the computational domain), and the box is now made to fit the pipe shape. And the box wall boundary condition will be real wall (now the pipe walls). (5). It up to you to look at the problem, you can make it either internal flow or external flow.

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