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how to get the stream tube of waterjet inlet in the whole flowfield?

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Old   July 25, 2012, 21:48
Question how to get the stream tube of waterjet inlet in the whole flowfield?
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Wang Chao
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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.
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Old   July 26, 2012, 07:40
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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.
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Old   July 26, 2012, 09:18
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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?
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Old   July 26, 2012, 19:23
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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.
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Old   July 26, 2012, 21:33
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Thanks, I will try to do it.
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Old   August 7, 2012, 02:55
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Quote:
Originally Posted by ghorrocks View Post
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.
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Old   August 7, 2012, 19:28
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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.
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Old   September 14, 2012, 04:53
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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?
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Old   September 14, 2012, 07:49
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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.
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Old   September 15, 2012, 06:15
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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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