# T-Shape

This example demonstrates creating a T-shaped geometry using boolean operations.

![T-shape geometry](/_static/FIGURES/salome17.jpg)

## Setup

```bash
mkdir -p TRUST_tutorials/salome/exo3
cd TRUST_tutorials/salome/exo3
$PathToSALOME/salome &
```

- Create a new study: File → New
- Select the Geometry module
- Save frequently in HDF format

## Creating the Base Cylinders

- **Create two cylinders:** New Entity → Primitives → Cylinder
  - **Cylinder_1:** Radius `0.5`, Height `5` → "Apply"
  - **Cylinder_2:** Radius `0.3`, Height `3` → "Apply and Close"

## Positioning the Second Cylinder

- **Rotate Cylinder_2:** Operations → Transformation → Rotation
  - Name: `Rotation_1`
  - Object: Cylinder_2
  - Axis: OY
  - Angle: `90°`
  - Click "Apply and Close"

  ![Rotation step](/_static/FIGURES/salome11.jpg)

- **Translate the rotated cylinder:** Operations → Transformation → Translation
  - Name: `Translation_1`
  - Object: Rotation_1
  - Dx = 0, Dy = 0, Dz = 1.5
  - Click "Apply and Close"

  ![Translation step](/_static/FIGURES/salome12.jpg)

## Fusing the Cylinders

**Combine the cylinders:** Operations → Boolean → Fuse
- Name: `Fuse_1`
- Selected Objects: 2 objects (use "Ctrl" to select both Cylinder_1 and Translation_1)
- Click "Apply and Close"

  ![Fuse result](/_static/FIGURES/salome13.jpg)

  ![Fuse dialog](/_static/FIGURES/salome14.jpg)

## Creating Boundaries

### Extracting Individual Faces

For each outlet/inlet face:

- **Extract faces:** New Entity → Explode
  - Main Object: Fuse_1
  - Sub-shape type: Face
  - Select "Select sub-shape"
  - Click on the desired surface in the visualization window
  - Click "Apply"

- **Rename the face:**
  - The face will be created as "Face_1" under Fuse_1
  - Right-click and select "Rename"
  - Rename to: `Outlet`, `Inlet_x`, or `Inlet_z`

  ![Face extraction](/_static/FIGURES/salome15.jpg)

### Creating the Wall Group

- **Create a surface group:** New Entity → Group → Create Group
  - Shape Type: Surface
  - Name: `Wall`
  - Main Shape: Fuse_1
  - Click on the lateral surface of Cylinder_1 → "Add"
  - Click on the lateral surface of Translation_1 → "Add"
  - Click "Apply and Close"

  ![Wall group](/_static/FIGURES/salome16.jpg)

### Creating a Corner Point

This point will be used for local mesh refinement:

- **Extract a vertex:** New Entity → Explode
  - Main Object: Fuse_1
  - Sub-shape type: Vertex
  - Select "Select sub-shape"
  - Click on the chosen corner point
  - Click "Apply and Close"

- **Rename:** Rename "Vertex_1" to `Corner`

## Creating the Mesh

- **Switch to the Mesh module** from the drop-down menu

- **Display the geometry:**
  - Select "Fuse_1" in the Object Browser
  - Right Click → 'Show' (or click the eye icon)

- **Create the mesh:** Mesh → Create Mesh
  - Select "Fuse_1" as the geometry

- **Configure the 3D algorithm:** Choose "Netgen 3D"

- **Add viscous layers:**
  - Click the wheel icon next to "Add. Hypothesis" → "Viscous Layers"
  - Total thickness: `0.05`
  - Number of layers: `3`
  - Stretch factor: `1.1`
  - Extrusion method: Node Offset
  - Add the "Wall" group to "Faces with layers (Wall)"
  - Click "OK"

- **Configure the 2D algorithm:** Choose "Netgen 1D-2D"

- **Set 2D parameters:**
  - Click the wheel icon next to "Hypothesis" → "Netgen 2D parameters"
  
  **Arguments menu:**
  - Max. Size: `0.6`
  - Min. Size: `0`
  - Fineness: Custom
  - Growth rate: `0.1`
  - Nb. segs per Edge: `2`
  - Nb. segs per Radius: `4`
  - ☑ Limit size by Surface Curvature
  - ☑ Optimize
  - ☐ Allow Quadrangles
  - ☐ Second Order

  **Local Size menu:**
  - Select the "Corner" object in the Object Browser
  - Click "On Vertex"
  - Set value to `0.01`
  
  **Advanced menu:**
  - ☑ Fuse Coincident Nodes on Edges and Vertices
  
  - Click "OK"

- **Apply and compute:**
  - Click "Apply and Close"
  - Select "Mesh_1"
  - Right Click → Compute

### Converting to a Tetrahedral Mesh

- Select "Mesh_1" in the Object Browser
- Go to: Modification → Split Volumes
- Select "Tetrahedron"
- Keep the default parameters
- Click "Apply and Close"

### Exporting and Saving

- **Verify boundaries:** Check that all four boundaries appear under "Group of Faces" of **Mesh_1**

- **Export the mesh:**
  - Select "Mesh_1"
  - Right Click → Export → MED file
  - Save as `Mesh_1.med`

- **Save the study:**
  - HDF format: File → Save/Save As...
  - Python format: File → Dump Study...

```{note}
The solution file (`T_shape.py`) is available at: `$TRUST_ROOT/doc/TRUST/exercices/salome`
```

## Running with TRUST

Copy and run the TRUST data file:

```bash
cp $TRUST_ROOT/doc/TRUST/exercices/salome/T_shape.data .
trust T_shape
```

Or run in parallel:

```bash
trust -partition T_shape
trust PAR_T_shape 4
```

Visualize the results with VisIt or SALOME by opening:
- Sequential: `T_shape_0000.med`
- Parallel: `PAR_T_shape_0000.med`

  ![Visualization with VisIt](/_static/FIGURES/salome18.jpg)