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

Aisun · July 25, 2012, 21:48

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?

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

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

Quote:

Originally Posted by ghorrocks

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

Quote:

Originally Posted by ghorrocks

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!

July 25, 2012, 21:48	how to get the stream tube of waterjet inlet in the whole flowfield?	#1
Aisun New Member Wang Chao Join Date: Jul 2012 Location: China Posts: 8 Rep Power: 7	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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July 26, 2012, 07:40		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,808 Rep Power: 107	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.

July 26, 2012, 09:18		#3
Aisun New Member Wang Chao Join Date: Jul 2012 Location: China Posts: 8 Rep Power: 7	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?

July 26, 2012, 19:23		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,808 Rep Power: 107	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.

July 26, 2012, 21:33		#5
Aisun New Member Wang Chao Join Date: Jul 2012 Location: China Posts: 8 Rep Power: 7	Thanks, I will try to do it.

August 7, 2012, 19:28		#7
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,808 Rep Power: 107	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.

September 14, 2012, 07:49		#9
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,808 Rep Power: 107	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.