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November 3, 2011, 13:06 |
Translation of an airfoil
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#1 |
New Member
Join Date: Jul 2011
Location: London, UK
Posts: 6
Rep Power: 14 |
Hi all
I am having problems with getting a NACA 0012 airfoil to translate vertically with harmonic motion. I have followed the ANSYS tutorials and tried to set my problem up in a similar way. I am using a tet c-mesh you can see attached. I have a problem when my airfoil oscillates as elements seem to fold rather than remesh, resulting in a negative volume error. This is shown in the second attachment, you can see at the top of the airfoil the elements are folding and on the bottom of the airfoil the elongated elements. I am using define_cg_motion to oscillate the airfoil. Thanks in advance Phil |
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November 5, 2011, 09:02 |
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#2 |
Member
Zachariah Swetky
Join Date: Aug 2011
Posts: 36
Rep Power: 14 |
Would defining a UDF of the motion and applying it to Cell Zone Conditions > Mesh Motion > Translation work? I think this solves the same physics without the need for mesh adaptation.
-Zachariah |
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November 7, 2011, 06:54 |
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#3 |
New Member
Join Date: Jul 2011
Location: London, UK
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How would I go about defining a UDF for this as I have been using Define_CG_Motion which I dont think is suited to this case.
Also how would applying a cell zone motion solve the same physical problem? Sorry if my questions seem basic but I am fairly new to CFD. Thanks Phil |
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November 7, 2011, 09:18 |
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#4 |
Member
Zachariah Swetky
Join Date: Aug 2011
Posts: 36
Rep Power: 14 |
According to the user guide, by using a Single Moving Reference Frame, the accelerations due to the motion of the frame are accounted for by the solver. This means that as long as your boundary conditions represent the problem correctly, the same physics will be solved.
As far as the UDF is concerned, my knowledge is limited. It seems to me that this is the only way to define non-constant motion for a moving frame is a UDF. If this approach is too cumbersome, you may try implementing the non spring-based dynamic mesh method that removes cells once they become too small. |
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November 7, 2011, 16:03 |
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#5 |
Senior Member
Vieri Abolaffio
Join Date: Jul 2010
Location: Always on the move.
Posts: 308
Rep Power: 16 |
remeshing does not work on hexa cells. [Ref, Fluent guide]
to get some remeshing you need to mesh your bl and then some as hexa, and the farfield as tri. then set all the hexa domain as passive rigid body. there are quite a few tutorial for this on the web. or, not using a c-type grid but a normal h-type, you could take advantage of the relayering option. |
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