Rectangular object falling into water

Esosa · August 18, 2009, 08:13

Hello,

I am attempting to simulate a rectangular object falling into water released from a height at an angle as a 2D problem. I have created the geometry and when I use blockMesh, a mesh is generated as well as a long list of FOAM Warnings. When viewed in Paraview, the outline is fine but the wireframe of the mesh is quite 'spectacular'.

Can anyone kindly help me out with this?

A short (very) sample of the warning message is:

--> FOAM Warning :
From function blockMesh::createTopology(IOdictionary&)
in file createTopology.C at line 412
negative volume block : 13, probably defined inside-out

Regards,
Esosa.

ngj · August 18, 2009, 08:32

Hi Esosa

The problem is that you do not follow to the correct orientation of the blocks, when you are defining your mesh. It is necessary to follow the same convention all the time. If in doubt look in the User Guide chapter 6.

As a rule of thump, the first node pair should point in the x-direction, the second in the y-direction and the z-plane should be a translation of the first four nodes. The vector between the sixth and the fourth nodes should point in the same general direction as the vector between the second and the first node.

Best regards,

Niels

Esosa · August 18, 2009, 10:34

Thanks Niels. Problem fixed.

August 18, 2009, 08:13	Rectangular object falling into water	#1
Esosa New Member N/A Join Date: Jun 2009 Posts: 4 Rep Power: 17	Hello, I am attempting to simulate a rectangular object falling into water released from a height at an angle as a 2D problem. I have created the geometry and when I use blockMesh, a mesh is generated as well as a long list of FOAM Warnings. When viewed in Paraview, the outline is fine but the wireframe of the mesh is quite 'spectacular'. Can anyone kindly help me out with this? A short (very) sample of the warning message is: --> FOAM Warning : From function blockMesh::createTopology(IOdictionary&) in file createTopology.C at line 412 negative volume block : 13, probably defined inside-out Regards, Esosa.

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August 18, 2009, 08:32		#2
ngj Senior Member Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,903 Rep Power: 37	Hi Esosa The problem is that you do not follow to the correct orientation of the blocks, when you are defining your mesh. It is necessary to follow the same convention all the time. If in doubt look in the User Guide chapter 6. As a rule of thump, the first node pair should point in the x-direction, the second in the y-direction and the z-plane should be a translation of the first four nodes. The vector between the sixth and the fourth nodes should point in the same general direction as the vector between the second and the first node. Best regards, Niels

August 18, 2009, 10:34		#3
Esosa New Member N/A Join Date: Jun 2009 Posts: 4 Rep Power: 17	Thanks Niels. Problem fixed.