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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Can't select workplane as input object in order to extrude it

Posted 2011年4月13日 GMT-4 13:17 Geometry Version 4.2, Version 4.4 3 Replies

Hector Alan Aguirre Soto
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Hi,

I am working in what is called the "Backstep" problem, which is basically simulating fluid flow inside a pipe connected to a block-shaped tank (modeling one eight of the geometry). I am sort of following instructions given in a workshop, but I ran into a complication. Apparently, after creating the geometry with the CAD tools in COMSOL I need to create a workplane, then a Bezier polygon, and then extrude the workplane, before creating an intersection(this to end up with the one eight of the original geometry created, I think). Though, when Extrude the workplane, I then change the Distance from Workplane and "Build Selected", but I get an error message saying that I need to input the objects. But when I go back and try to select the workplane, I can't. It just does not want to be added.

Do you have any clue as to why is this happening?
3 Replies Last Post 2014年11月3日 GMT-5 17:16
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2011年4月13日 GMT-4 15:40
Hi

I'm not sure I catched it all, I do believe that your approach is correct though, but I do not really understand the error you get.

Another way is to make a 3D block, then copy rotate it around the (0,0,0) (0,0,1) axis to cut out the 1/8th of symmetry.
You then make a difference adding what is to be kept, and subtracting both blocks (even if they overlap)

--
Good luck
Ivar
Hi I'm not sure I catched it all, I do believe that your approach is correct though, but I do not really understand the error you get. Another way is to make a 3D block, then copy rotate it around the (0,0,0) (0,0,1) axis to cut out the 1/8th of symmetry. You then make a difference adding what is to be kept, and subtracting both blocks (even if they overlap) -- Good luck Ivar
Jeramy Stewart
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Posted: 1 decade ago 2012年8月7日 GMT-4 11:50
Hello,
I had the same problem. Notice how it says "Geometry", instead of "Geometry 1". To access "Geometry", you must expand the Work Plane 1 (wp1) node. From there you can right-click "Geometry" and select the Bezier Polygon.
Hello, I had the same problem. Notice how it says "Geometry", instead of "Geometry 1". To access "Geometry", you must expand the Work Plane 1 (wp1) node. From there you can right-click "Geometry" and select the Bezier Polygon.
DW
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Posted: 1 decade ago 2014年11月3日 GMT-5 17:16
This error ("You need to provide input objects") will happen in the tutorial "Creating a 3D Geometry Model" if you forget to clear the "Unite with input objects" check box. If you don't clear the check box, then "wp1" will *not* be available for your *second* operation. For example, you will be able to do the revolve, but
when you try to do the extrusion (see the tutorial), you will not be able to select "wp1"; if you press "Build selected" without having selected any input object(s), then you will get the error "You need to provide input objects."
To solve: go back to the first operation (e.g. revolve), and clear the check box "Unite with input objects". Now when you do the second operation (e.g. extrude), you will be able to select "wp1".
-DW
This error ("You need to provide input objects") will happen in the tutorial "Creating a 3D Geometry Model" if you forget to clear the "Unite with input objects" check box. If you don't clear the check box, then "wp1" will *not* be available for your *second* operation. For example, you will be able to do the revolve, but when you try to do the extrusion (see the tutorial), you will not be able to select "wp1"; if you press "Build selected" without having selected any input object(s), then you will get the error "You need to provide input objects." To solve: go back to the first operation (e.g. revolve), and clear the check box "Unite with input objects". Now when you do the second operation (e.g. extrude), you will be able to select "wp1". -DW

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