Self coded 1dof pitch code differs from OF's after 1.4s

quarkz · August 2, 2022, 22:06

Hi,

I am trying to create my own 6dof code to suit my problem.

I have created a 1dof y translation and it compares very similar to OF's own 6dof solver results.

Now I'm trying to create a similar 1dof pitch rotation. It uses the same algorithm as OF's 6dof solver, using the newmark interpolation scheme.

I found that for this case, the results (force,moment,pitch angle) are very similar up to around t=1.4s. It then starts to show some divergence between the two.

I wonder why this is happening. I checked the code and it follows similar coding to the 1dof y translation, only replacing the translation with the pitching rotation.

Can someone give some hints so to what could have caused the difference?

Thanks.

quarkz · August 3, 2022, 03:11

Update:

I run until around t ~ 3s.

I found that there's some noticeable difference in the orientation of the airfoil. However, even at t = 3s, the difference is not big. Hence, the difference has not diverged. But at the same time instant, the velocities are different.

August 2, 2022, 22:06	Self coded 1dof pitch code differs from OF's after 1.4s	#1
quarkz Senior Member TWB Join Date: Mar 2009 Posts: 401 Rep Power: 19	Hi, I am trying to create my own 6dof code to suit my problem. I have created a 1dof y translation and it compares very similar to OF's own 6dof solver results. Now I'm trying to create a similar 1dof pitch rotation. It uses the same algorithm as OF's 6dof solver, using the newmark interpolation scheme. I found that for this case, the results (force,moment,pitch angle) are very similar up to around t=1.4s. It then starts to show some divergence between the two. I wonder why this is happening. I checked the code and it follows similar coding to the 1dof y translation, only replacing the translation with the pitching rotation. Can someone give some hints so to what could have caused the difference? Thanks.

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August 3, 2022, 03:11		#2
quarkz Senior Member TWB Join Date: Mar 2009 Posts: 401 Rep Power: 19	Update: I run until around t ~ 3s. I found that there's some noticeable difference in the orientation of the airfoil. However, even at t = 3s, the difference is not big. Hence, the difference has not diverged. But at the same time instant, the velocities are different.