[aamer]

Hello all....

i am trying to do flapping motion by using dynamic mesh, DEFINE CG MOTION macro. i have given the wing and default interior as rigid body in dynamic zone. NOw there are two ways to preview the motion. 1. DISPLAY> ZONE MOTION 2. SOLVE> MESH MOTION. the problem is not that i am not getting identical motion from both methods.

What can be the possible cause of getting different type of motions from the two methods and which one to be trusted ?

[fluentworkshop]

Hi
I think that mesh motion is trust.
because this motion is in real time.

[aamer]

Originally Posted by fluentworkshop

Hi
I think that mesh motion is trust.
because this motion is in real time.

Hello....

and what could be the possible reasons for not getting identical motions from the two types of previews?

[cfd seeker]

i have given the wing and default interior as rigid body in dynamic zone

Correction for you....don't define "default interior" as rigid body rather leave it as it is....

[aamer]

Originally Posted by cfd seeker

Correction for you....don't define "default interior" as rigid body rather leave it as it is....

Hello cfd seeker.

Thanks for the reply. if i dont define default interior as rigid body, mesh motion preview shows no motion and gives error of negative volumes and the computation also do not run because of negative volumes. please note that i have used DEFINE CG MOTION macro udf and i have used layering with default settings. I even tried to run the calculations with smaller time steps but still negative volume appeared. My mesh is 3D structured so i didnt go for remeshing option.

[cfd seeker]

Originally Posted by aamer

Hello cfd seeker.

Thanks for the reply. if i dont define default interior as rigid body, mesh motion preview shows no motion and gives error of negative volumes and the computation also do not run because of negative volumes. please note that i have used DEFINE CG MOTION macro udf and i have used layering with default settings. I even tried to run the calculations with smaller time steps but still negative volume appeared. My mesh is 3D structured so i didnt go for remeshing option.

But default interior is nothing, its not a zone in your mesh. Turn on also "Smoothing" it works for both Structured and Unstructured meshes with "Spring Constant Factor" set as "zero"