> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ntop.com/llms.txt
> Use this file to discover all available pages before exploring further.

# FE Region by Body

## About this Block

**What it does:** Selects the FE Mesh elements whose center of mass lies within the tolerance value of the implicit body.

**Commons uses:**

* Choosing areas for defining material and elemental properties.
* Choosing elements for Boundary Conditions.

**Tips:**

* This block selects elements that are present within the FE Mesh. These elements include beams, shells, or cells (including interior cells).

* **How to decide which Entity type to choose:**
  * Choosing your entity depends on the type of elements available in the mesh.
    * Cells can only be selected on an **FE Volume Mesh**.
    * Shells can only be selected on **FE Surface Mesh** and **FE Lattice Mesh** (only if the lattice contains faces).
    * Beams can only be selected on beam-based FE Lattice Meshes.

## Example File

Download Example: [FE Region by Body](https://storage.googleapis.com/files-learn/static/ExtendedBlockDocs/selections.ntop)

![FE Region by Body](https://storage.googleapis.com/files-learn/static/ExtendedBlockDocs/fe_region_body.png)

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Select elements in an FE Mesh using an Implicit Body. Elements with their center of mass lying within a defined tolerance of the Implicit Body will be selected.

### Inputs

| Name | Type | Description |
| - | - | - |
| Mesh | [FE Mesh](../../../../block-documentation/types/fe-mesh) | The finite element mesh. |
| Entity | FE Interior Region Enum | The type of mesh entity to select. |
| Body | [Implicit Body](../../../../block-documentation/types/implicit-body) | The implicit body to select with. |
| Reverse | [Bool](../../../../block-documentation/types/bool) | Option to select entities outside the implicit body instead of inside. |
| Tolerance | [Scalar](../../../../block-documentation/types/scalar) | The tolerance for checking at the implicit body's Region. A positive value will effectively extend the region while a negative value will shrink it. |
| Name | [Text](../../../../block-documentation/types/text) | Optional name for this set in the exported file. |

### Outputs

| Type |
| - |
| [FE Region](../../../../block-documentation/types/fe-region) |


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