Why Do Intersections Errors Happen While Defining a Volume For A 3D Mesh ?

Meshes are primarily composed of two distinct entities: the geometry (the position x, y, and z of the nodes) and also the topology (how the nodes are connected).

What is a Mesh?

A mesh may be a network that's formed of cells and points. It can have almost any shape in any size and is employed to unravel Partial Differential Equations. Each cell of the mesh represents a personal solution of the equation (all unknowns of equations) which, when combined for the entire network, ends up in an answer for the whole mesh.

Solving the complete region without dividing it into smaller pieces is impossible due to the complexity involved within the domain. Holes, corners and angles can make it extremely difficult for solvers to get an answer. Small cells, on the opposite hand, are comparably easy to unravel and so is the popular strategy.

How Do Intersection Errors Show Up in a 3D Mesh?

- Below mentioned image shows the error pop-up:

Let’s understand it with the help of an example.

The component shown below has two parts included in it.

 

Penetration: Intersections error occurs during a volume mesh when you have defined volumes (Volume deck > Volumes > Define) of two parts together as a single Volume list.

Note: You can see a list of volumes defined by doing V.Mesh > Volume > List. (Refer to Figure 3).

This error may also come when there is a common surface for two different parts (i.e Triple CONS in the model) or if the surfaces of two components are very close together.

Now Right click on the selected ID 1 and select “Remesh”. (Refer Fig.4)

You will be able to see the error pop-up which shows the Penetration: Intersections error as Shown in Fig 1. 

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Now let's solve the above issue by defining the volume for both part volumes separately. 

Step 1:

- Define the volume for the inner separated part volumes as shown in Fig 5. 

- Isolate one part alone in GUI

- Goto Volume deck > Volumes > Define > Manual 

- Select the whole part 

- On a middle click confirmation you will see a Property help window popping up.

- Then follow these steps to create a new PID for Volume: Right click > New > PSOLID

- You can see a window popping up which asks to enter the details of the PSOLID.

- Rename it and click Ok. 

- Now you can see that a PSOLID Id is created on the Property help window.

- Double-click on the Id and the property will be assigned to that newly created PID. 

- Now open the Volumes > List tab from the volume deck, you can see the following pop-up window.

- Right-click on the Id and select Remesh.

- You can see another window popping up where you can select the type of mesh generation algorithm.

- Select Tetra FEM and select Ok. 

- Now if we check the Volumes > List, it shows the status as Meshed.

- Follow the same steps to mesh the other outer part.