In the following tutorial we will learn how to create a mesh with boundary layer based on a pipe tee geometry. At the beginning we will use cut-cell method to create a mesh without boundary layer. Then we will reduce mesh cell count by taking advantage of our geometry having a symmetry plain. We will also learn how to control the process of snapping nodes to geometry to achieve appropriate mesh quality. In the end we will learn how to add boundary layer to the mesh and control its parameters.
Before we start this tutorial download geometry file which we will later use for the meshing process.
Start simFlow and when the launcher window appears:
- Type case name, eg.
- Click on the Create Case button or press ENTER three times to start the program.
Import Geometry (I)
- Click Load Geometry button in the Geometry panel
- Select geometry file in the file browser
- Click Open to load the geometry
- Click on the ZY button to aling the 3D workspace view with the ZY plane.
Split Geometry (I)
The geometry consist of a single face. To apply different boundary conditions on different parts of the geometry you need to split it into different faces.
- Click Options button next to the
- Click Split in the drop-down menu
Split Geometry (II)
- Leave all the default values and click Split
Create Face Groups (I)
After the split operation the geometry consists of four faces. You will now put each of those faces in the separate named group.
- Click Geometry Faces button to show face groups
- While holding Ctrl key click on one of the circular faces
- Click Create New Face Group button
- Select Create Group From 3D Selection option
Create Face Groups (II)
New group named
group_1 containing one face was now created. You will now give this group a more meaningful name.
- Double click on the
group_1name and input
inlet1. Press Enter to apply.
Create Face Groups (III)
Repeat steps 1-4 for two other circular faces and name them
Geometry Meshing Parameters
- Go to Hex Meshing panel
- Click to enable meshing on the
- Click on
pipe_teeto view options
- Increase max refinement level to
1. In this case this option will allow system to refine regions with sharp edges. Setting the max value to
1will split cells into 8 equal hexahedrons near any sharp feature of the geometry.
Now you need to define base mesh which will be cut using geometry.
- Go to Base tab
- Click Autosize button to adjust the base mesh size to fit currently visible geometries in the 3D workspace
- Setup mesh division in each direction
To obtain best results in mesh generation process it is very important to keep, as much as possible, the same mesh size in each direction. As you can see, current division provides similar size for each of the three directions.
Material Point informs system where the mesh should be generated – inside or outside the geometry. In our case we cut cells from the base mesh using pipe tee geometry. Since the geometry is of surface type, we need to decide which part of our base mesh should be removed and which should be retained for further processing. Our mesh has to be generated inside the pipe and as we can see default location suits our needs. If for example we would like to generate mesh outside the pipe, then we can type explicitly proper point location or use orange arrows in 3D workspace to adjust position.
- Go to Mesh tab.
- Click the Mesh button to start the meshing process. New dialog will pop out and it will lock simFlow for the working time. You can stop meshing any time you want. If you have already created mesh, then stopping the application will leave the old mesh unchanged.
View the generated mesh. You may rotate the camera by dragging the mouse with the left mouse button pressed. Similarly you can pan the view with the middle mouse button. Try to zoom the view to see how the mesh is refined near the sharp edges. Zooming can be performed using the mouse wheel or by dragging the mouse with the right button pressed.
Mesh Section (I)
Now we can create a mesh section to see how cells look like inside the domain.
- Close the console panel to enlarge the 3D workspace on the screen.
- Click the Section icon to open options.
Mesh Section (II)
- Click on the X button to select plane with normal vector in the X direction (YZ plane).
- Click on the Mesh Center to locate section plane in the center of visible geometries in the 3D workspace.
- Check the Section View option in the panel title bar to enable section.
Mesh Section (III)
- Close section window by pressing again the section icon icon or by pressing Esc button.
- Click ZY to align the camera with that plane.
After this operations you can zoom in to see mesh internal cells.
Mesh Section (IV)
Open the section window once again to switch off the section view.
- Uncheck the Section View option to suppress the section view.
- Close the window by clicking the Section icon.
Add Boundary Layer
- Move back to Hex Meshing panel since system moves automatically to solver selection after creation first mesh
- Go to Geometry tab
- Switch on boundary layer
pipe_teegeometry to view meshing options assigned to this object
- Make sure that the number of boundary layers is set to 5
Create Symmetry Plane
The geometry we are working on is symmetrical. It is very convenient to take advantage of this feature. We can reduce by half the number of unknowns to be solved and therefore the computation time. To apply symmetry to the mesh we only need to shrink our base mesh and set appropriate boundary type to inform meshing tool where the mesh should be constrained.
- Go to
- Set X coordinate of base mesh min point to 0.
- Decrease division in X direction by half to maintain the same cell size as before
- Change Plane X- name to
- Change Plane X- type to
Meshing with Boundary Layers
- Go to Mesh tab.
- Click the Mesh button to start the meshing process.
View Layers on Boundaries (I)
After mesh is created, click View XY button to align camera with the XY plane. Next zoom in to check the generated layer on the top inlet boundary.
View Layers on Boundaries (II)
Click the View ZY button to align the camera with the ZY plane and zoom in to check the right inlet boundary.
View Symmetry Plane (I)
Now look at the mesh on the symmetry plane. Rotate the view so that you can see symmetry plane, then:
- Click View Normal button in the 3D workspace toolbar.
- When the panel is opened press Ctrl key and left-click on the symmetry plane boundary. After clicking on the boundary, the camera will align to the symmetry plane. If the camera is correctly aligned, you can close View Normal panel by pressing Esc button.
View Symmetry Plane (II)
Zoom in using the mouse wheel to examine the boundary layer on the symmetry plane. Now check how boundary layer is generated in the direction perpendicular to the symmetry plane.
- Open Section View panel by clicking icon in the 3D workspace toolbar.
View Y Section (I)
- Click Y to asign [0, 1, 0] vector as section plane normal
- Click Mesh Center button to locate the plane in middle of the mesh
- Switch on Section View option by clicking the checkbox
- Close Section View panel by clicking once again on the icon in toolbar
- Rotate the view so that you can see the boundary layer on the section plane.
This concludes this tutorial.