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 jeff April 19, 2001 13:20

how to get streamline

Hi! I have some question about post-processor of computed results. I have already got the velocity fields for 3-D flow. And I also got the velocity fields on the 2-D intersection planes. Since there is no stream function for 3-D flow. Is any one able to propose how to get the streamline for the velocity field on 2-D intersection planes? Or is there some method for this case? Thanks!

 John C. Chien April 19, 2001 13:34

Re: how to get streamline

(1). For 3-D flows, the streamline will become a point on a 2-D plane.

 Kike April 20, 2001 04:32

Re: how to get streamline

Dear Jeff

You can trace the path for imaginary massless particles inside the 3D domain and you will have a picture close to "3D streamlines".

Is it what you want, or you need a 2D well defined stream function in every plane?

Regards

Kike

 Anthony Wachs April 20, 2001 07:53

Re: how to get streamline

Hi Jeff, I faced the same problem some months ago for 3D calculations. According to me, a efficient way to obtain streamlines (both in 2D planes or directly in your 3D geometry) is a very simple one : 1. choose some points at the entry of your domain 2. follow their displacement using the velocity vectors, from one finite element (or volume) face to another. As you the point reach on an face will probably differ from the grid points, just use interpolations to calculate the velocity vector on this point. 3. Do this until the streamline reach the exit of your domain. 4. If you have secondary flows (recirculations) in your flow geometry, just choose the starting points in this zone.

I have used this method to compute the streamlines in 3D pipes with abrupt contraction of their section. It worked very well!!