sliding mesh or dynamic mesh for transient simulation

zagros135 · October 28, 2022, 15:20

hi everyone. i want to simulate an oscillating-pitching- airfoil in unsteady flow situation. which one of these methods do you think is good? sliding mesh or dynamic mesh? and why?

with regards.

Gert-Jan · October 29, 2022, 04:01

That depends on how your geometry looks like and the degrees of freedom it has.
With 2DOF, it can rotate around a fixed axis, put it in a cilinder.
With 3DOF, it can rotate around a point, put it in a sphere.
With 4DOF or more, it can also translate, then you require dynamic mesh.

zagros135 · October 29, 2022, 08:22

Quote:

Originally Posted by Gert-Jan

That depends on how your geometry looks like and the degrees of freedom it has.
With 2DOF, it can rotate around a fixed axis, put it in a cilinder.

well my geometry is 2d. and i put it in a circle and use the udf to rotate. but the problem is that when I run it, inner zone flow moves in a circle at first.

Gert-Jan · October 30, 2022, 06:31

This is 2DOF. Your wing can only rotate around a fixed axis.
But why is it a problem? Is the wing rotating to a neutral position? Shouldn't it do this? If not, then what do you expect? I can't read your mind.
And I don't know what is in your udf. Do you refer to the udf to describe the DOF? Or does it describe the wind fluctiations? Unclear to me........

October 28, 2022, 15:20	sliding mesh or dynamic mesh for transient simulation	#1
zagros135 New Member zagros Join Date: Apr 2022 Posts: 19 Rep Power: 3	hi everyone. i want to simulate an oscillating-pitching- airfoil in unsteady flow situation. which one of these methods do you think is good? sliding mesh or dynamic mesh? and why? with regards.

October 29, 2022, 04:01		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	That depends on how your geometry looks like and the degrees of freedom it has. With 2DOF, it can rotate around a fixed axis, put it in a cilinder. With 3DOF, it can rotate around a point, put it in a sphere. With 4DOF or more, it can also translate, then you require dynamic mesh. zagros135 likes this.

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October 30, 2022, 06:31		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	This is 2DOF. Your wing can only rotate around a fixed axis. But why is it a problem? Is the wing rotating to a neutral position? Shouldn't it do this? If not, then what do you expect? I can't read your mind. And I don't know what is in your udf. Do you refer to the udf to describe the DOF? Or does it describe the wind fluctiations? Unclear to me........