2D meshing of tandem cylinder in VIV for dynamic simulation
 

I have develop geometry and unstructured meshing of 2D model for tandem cylinder in VIV. The problem is, my meshing (line) around on the circle (represent the cylinder) and the wall_fluid (around cylinder) does not connected.

When i place the mesh into fluent for dynamic simulation, the cylinder break partially and cause error: Negative cell volume detected. How can i improve the meshing in order to have a proper part of cylinder and wall-fluid.

When i use structured meshing, the mesh around cylinder and wall_fluid does not have this problem. But i still have the error: Negative cell volume detected and that's the reason i move to unstructured mesh.

Please help me, i really need a clue on how to solve this.