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-   -   how to get the stream tube of waterjet inlet in the whole flowfield? (https://www.cfd-online.com/Forums/cfx/105238-how-get-stream-tube-waterjet-inlet-whole-flowfield.html)

Aisun July 25, 2012 21:48
how to get the stream tube of waterjet inlet in the whole flowfield?
 
As the title said, I have simulated the flowfield of a waterjet inlet. Some water of the whole flow field flow into waterjet inlet. I want to get the stream tube of the water that flow into waterjet in the whole flowfield. How to do it by CFX-post? Who can help me, THANKS.

ghorrocks July 26, 2012 07:40
You can approximate this by using a series of streamlines around the outside of the stream tube. Integrate them backwards from your outlet to see where they came from.

Aisun July 26, 2012 09:18
Look at the picture below. The streamline thrill through the plane and into the waterjet inlet. I want to get the inlet surface on the plane that just the streamline thrill through it. Would you like to tell me the detail approach?
http://ww3.sinaimg.cn/large/5d579ba1jw1dvajx2jzi5j.jpg

ghorrocks July 26, 2012 19:23
What you have already done is about right. You can see the stream tube from that.

If you want to define a surface to bound it you are going to have to take a different approach. You need to "tag" the inlet water somehow. If it is a different temeprature or composition then it is easy. If not you need to add a convected AV which separates the inlet water from the other. Then you can draw an isosurface of the AV to define your stream tube.

Aisun July 26, 2012 21:33
Thanks, I will try to do it.

Aisun August 7, 2012 02:55
Quote:
Originally Posted by ghorrocks (Post 373811)
What you have already done is about right. You can see the stream tube from that.

If you want to define a surface to bound it you are going to have to take a different approach. You need to "tag" the inlet water somehow. If it is a different temeprature or composition then it is easy. If not you need to add a convected AV which separates the inlet water from the other. Then you can draw an isosurface of the AV to define your stream tube.
I have creat an additional variable to tag the water. But I can only set the variable inlet condition but not the outlet condition by CFX-pre. So I think whether I can set the additional variable outlet condition. For example, I set the variable on one outlet condition 1, and set the other outlet condition 0. Then I can separate the inlet water from the other.

ghorrocks August 7, 2012 19:28
Of course, the tagged water just flows out of the outlet so no boundary condition needs specification for it at the outlet. This is a different approach to getting your stream tube. Draw an isosurface of the additional variable and you will have your stream tube.

Aisun September 14, 2012 04:53
Excuse me?
 
Quote:
Originally Posted by ghorrocks (Post 375923)
Of course, the tagged water just flows out of the outlet so no boundary condition needs specification for it at the outlet. This is a different approach to getting your stream tube. Draw an isosurface of the additional variable and you will have your stream tube.
Could you tell me how to operate in dedail?

ghorrocks September 14, 2012 07:49
No, I do not have time. There a lot of tutorials which come with CFX so I recommend you work your way through them. They show most of the features of the software.

Aisun September 15, 2012 06:15
thanks
 
Quote:
Originally Posted by ghorrocks (Post 381783)
No, I do not have time. There a lot of tutorials which come with CFX so I recommend you work your way through them. They show most of the features of the software.
Thank you all the same!


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