Re-meshing

Hi,

I have made a 3D model but i want to re-mesh it around some new wells that i imported. Is there an easy way to re-mesh the model with refinement around the new points, without having to build the geology ( and set the boundary conditions) all over again?

Thanks

Christian

Never mind, i found the solution.

Christian Bryn

Hi!

Can you explain, please, which is the fastest methodology for doing so?

Thanks,

What do you mean with methodology for doing so? Do you refer to the working steps within the Graphical User Interface (GUI)?

Hi,

Yes, thats it. if, for instance, I had only one well in my first mesh but I need to define new wells and then, I should refine my mesh, how should I do this?

Thanks again,

There are several ways available. The most suitable way depends on the available data. If your wells are available 3D map points you can drag & drop the map file from the Maps Panel to the Meshing panel. Accordingly, you constraint TetGen to locae computational points at this poistion. Furthermore, you have to tell TetGen which domain you want to re-mesh. The domain is given by an elemental selection. In a similar fashion, you have to drag & drop the elemental selection from the Selection panel to the Meshing panel. Please assure that the elemental selection must completly encapsulate the points.

Hello Bjorn,

I´m trying to remesh by the TetGen tool in feflow.

As you suggested, I carry on an elemental selection, I understand that this selection can be done in any of the layers of the model. In this case, as I want to study the heat transport in horizontal direction, I make the selection by a lasso in the topmost layer and then I copy the selsction to the rest of the layers.

Then, I open the meshing panel and I drag and drop from the Selection panel the selected element to the Mesh ítems in the meshing panel.

But here there are many options, and letting the default values something seems not to be working fine.
If I press to Generate Mesh, the selected elements dissapear from my Mesh view and in the entities panel each layer is converted from "Layer 1" to "Top of Layer 1" + "Bottom of Layer 1".

Please, can you tell what I´m doing wrong and what should I define in TetGen properties so that I obtain the remeshing right?

Thank you very much,

In general, the workflow is perfectly right. The conversion from "Layer 1" to "Top of Layer 1" + "Bottom of Layer 1" indicates that you re-meshed a 3D layered-based model (3D prismatic elements). The zone you re-meshed is now composed of tetrahedral elements connected to 3D prismatic elements which are located outside your re-meshed zone. The connection between re-meshed tetrahedrons and 3D prismatic elements is done via pyramids. The local unstructured elements (tetrahedrons and pyramids) disappear in the Slice View, because Slices / Layers do not exist anymore. However, you still see the elements outside the re-meshed domain, because 3D prismatic elements are still present. Accordingly, you use hybrid mesh composed of mixed elements.

You can even try to re-mesh the entire model domain. If you do this test, you will see that the Slice View completely disappears. No Slices / Layers are anymore available in fully-unstructured mesh environments. You have to work in the 3D View for fully-unstructured meshes or local re-meshed domains composed of tetrahedrons and pyramids.

If you do not want to work with fully- or partially-unstructured elements, you still can use a layered-based approach. You can refine the mesh locally within the Slice View by using the Mesh toolbar (not the Mesh panel) and drag + snap a mesh node a map point.

Hello Björn,

I am fairly new to modelling with Feflow and it is a steep learning curve.

So if I understand, improving our layered mesh using tetgen converts the mesh to unstructured, even if we turn on the switch to "preserve layers and element groups"

Is there a way to improve the mesh of a layered mesh other than Tetgen?  I have reviewed the Auxillary data in the Data panel, and I have quite a bit of spread on the histograms.

So I will just post my own learning here to help others.

What I have concluded is that for layered models, the initial smoothing operations after creating the 2D supermesh is the way to help form a good mesh. 

I realize after digging that for layered meshes, "Condition Number" in the auxiliary data (Data Panel), is the better item to review when trying to create a reliable mesh for a layered mesh (compared to a completely unstructured mesh).  I did do this smoothing mentioned above earlier, but found that my model was still showing a lot of spread in the condition number (from 1 to the 1000s). 

Then I realized that this was a problem in only one layer.  While creating the 3D mesh from the 2D mesh, I had a layer that was very thin and in some areas would "pinch" to the minimum thickness defined in the "problem settings">"Editor Settings">"Minimum slice distance" which I had set earlier to 0.1m.  So when I inspected some of the larger 3D elements in my 3D mesh, I realized they were "deformed" in the z direction (they were not a nice "slab" like some of the elements in thicker layers).

So I increased my minimum thickness to 1m, re-applied my elevations, and the popup asking me how to resolve slice elevations to adhere to minimum thickness came up.  I chose bottom up, and let Feflow reassign all the elevations but now with the thicker minimum thickness of 1m.  So now most of the red indicating a bad (high) condition number disappeared, and the scale legend showed max values that are in the 100s instead of 1000s.  Still some work to do, but much better.

In my case I have some leeway to change this minimum thickness. That may not be the case for all models.  I am not sure yet if the model would have trouble converging with these high condition numbers, but hopefully I will not need to find out :)

Hi, anyone help me on how to remesh my 3d layered model based on some polygon such as geology?
i want some nodes in boundaries of each geological zones