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Shared Nodes for surface and volume mesh elements

Altair Forum User

Hello all,

I am from a Geophysics background and I am attempting to use HyperMesh to generate a FE Mesh of some basic reservoirs containing different fracture or fault geometries

I am trying to mesh a a simplified model of a reservoir (volume) with two embedded intersecting faults (surfaces). I attached a picture of my simple geometry to give you an idea. I need the finite element mesh for flow simulations, however the simulation requires that the triangle elements of the fracture surface have shared nodes with the tetrahedron elements of the volume.

I was able to generate a mesh successfully, however it does not seem to have shared nodes because when I run my simulation there is no communication (fluid flow) between the fracture and the rest of the volume.

Can anyone help me with this issue? Is there a particular setting that I need to use to ensure that there are shared nodes between the surface and volume elements.

Currently, I mesh the surfaces first, using 'Create 2D AutoMesh' then create the volume around it and I mesh that using 'Tetra Mesh'

I would greatly appreciate any feedback you can give on this.

Thanks,

Ariel

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Altair Forum User

Currently, I mesh the surfaces first, using 'Create 2D AutoMesh' then create the volume around it and I mesh that using 'Tetra Mesh'

Hi,

can you explain what do you mean by 'create volume around it' ?

Usually when you create a tetramesh with a 2D mesh reference, the 2D and 3D elements will have shared nodes.

if not, delete the 2D elements and extract face elements. Tools page>> Faces to generate face elements. This will definitely share nodes with 3D elements.

Altair Forum User

Hi,

I first create the fractures and mesh them. Then I create two planes which represent the top and base of my reservoir. I then use Geometry>Create>Solids>Ruled Linear to generate a volume out of this.

Altair Forum User

I am not sure if the 2D mesh is being properly referenced in my approach to creating the volume mesh.

I have attached a screen shot of the settings I used to generate the volume mesh. There you can see the two faults are already meshed and I guess I used 'Volume Tetra' and not 'Tetra mesh' maybe this is the issue?

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Rahul Rajan_21763

Do you have access to simlab?If so it can be done in simlab with few clicks.

Rahul Rajan_21763

In Hm also if you use tetramesh with fix trias. it will work.

Altair Forum User

Thank you for the feedback, I do not think I have access to Simlab

I tried to use tetramesh with fix trias as suggested. I selected the fault surface elements but I get a an error message stating the Mesh is not enclosed. I created a close solid around the fracture surfaces, but I am not sure how to select it in the Tetra Mesh menu.

Ariel

Rahul Rajan_21763

tools page : edges panel would help you to fix free nodes.

you must get edges only for central 2d mesh part.

If you want i can share you mine meshed hm file.

Altair Forum User

I am currently creating my geometry from the command window. It consists of planes(representing fractures) surrounded by a box (representing a rock matrix)

Is there a way to set different material numbers for the tri elements of the planes and the tetra elements of the volume? Below is the command that I am using to generate the plane.

*createnode 0 0 0
*createnode 5000 0 0
*createnode 5000 5000 0
*createnode 0 5000 0

*createlist nodes 1 1 2
*linecreatefromnodes 1 1 150 5 179
*createlist nodes 1 2 3
*linecreatefromnodes 1 1 150 5 179
*createlist nodes 1 3 4
*linecreatefromnodes 1 1 150 5 179
*createlist nodes 1 4 1
*linecreatefromnodes 1 1 150 5 179

*createmark lines 1 1 2 3 4
*createplane 1 1 0 0 0 0 0
*splinesurface lines 1 1 1 1

I would like the planes (fractures) to have a material number of zero and the volume that I created around to have a material number of 1.

Is there a way to include this in the command? I inherited these commands from an example project so I am not actually sure what some of the numbers actually mean

Cheers,

Ariel

Altair Forum User

tools page : edges panel would help you to fix free nodes.

you must get edges only for central 2d mesh part.

If you want i can share you mine meshed hm file.

I checked the tools menu and I do not see any edges panel.. I am using HyperWorks v14.0