Working with geometries

What you’ll learn?

• Creating geometric shapes: Create simple geometries using geometry shapes.
• Importing geometry related files: Use STEP, GDSII or mesh formats imports to set up the project.
• Modifying geometry: Use simple and boolean operations to make modifications to your model.

Quanscient Allsolve geometry editing is done in Model section. At the top of the Navigation panel, you’ll find the elements list followed by the geometric entity tree.

Only after confirming the model, the geometry entity tags are locked which is used to target all definitions in the subsequent sections. Therefore, it is recommended to confirm the model changes before moving to the next section. Not doing so may result in selecting incorrect entity tags which leads to simulation error.

Provided geometry elements

All shapes, imports and operations are referred to commonly as Geometry elements.

• Import
  • Import step, GDSII or mesh (gmsh or nastran mesh) files
• Shapes
  • Box
  • Sphere
  • Cylinder
  • Torus
  • Cone
  • Rectangle (2D)
  • Disk (2D)
• Simple operations
  • Remove - Remove volumes.
  • Translate - Move selected volumes or create new copies by translating the selected volumes.
  • Rotate - Rotate selected volumes or create new copies by rotating selected volumes on defined axis.
• Boolean operations
  • Intersection - Portion common to both volume sets is kept.
  • Union - Merge all selected volumes/surfaces.
  • Difference - Subtracts volume set 2 from volume set 1.
  • Fragments - Split overlapping volumes into new, non-overlapping volumes.
  • Fragment all - Run automatic fragment of all against all. There is always an implicit Fragment all forced as the last element to prevent any overlapping elements.

Building elements

The geometry element list can be thought of as a stack where each new element is on top of all previous ones. When adding new geometric shapes this does not have to be taken into account but for targetting any operations it’s important to understand that each operation is working with entity tags of the state just before the operation.

Geometry element list

As an example let’s consider the above case with a step import and two boxes. When adding the difference operation, it can not be edited before the previous element (box 2) is built and geometric entities up until that point are known.

The requirement goes also in the other direction. If you have built the difference operation and want to edit that, the difference must first be “unbuilt” so that tag selection will be correct. This can be done by building the previous element or by clicking the Edit button in difference operation settings panel.

When you are finished editing the model, build the final state of the model by clicking on Confirm model changes.

Confirm the model

It is important to remember to confirm the model so that entity tags are locked before starting to work on defining materials and physics so the regions will have correct tags.

Adding shapes

In Quanscient Allsolve, you can add various shapes to your project by following these steps:

1. If you haven’t yet activated geometry edit mode, do that by clicking Edit model.
2. Select the option to add new geometries from the available list of shapes and operations.
3. Add your choice of shape.
4. Adjust the properties of the added shapes as necessary.
5. Click on Apply to confirm and set the properties.
6. Press the “Confirm model changes” button to finalize the changes and update the model and entity lists.

Adding operations

There’s a selection of simple operations: remove, translate and rotate, as well as the common boolean operations.

The operations have a target selection and possibly some settings to set before the operation can be applied and built. A special case is fragment all -operation that does not require any target or settings.

Translate and rotate copy operation

There is one special case in geometry operations for translate and rotate operations. You can enable copying and set the number of copies you want to create.

Each copy is then rotated or translated by the amount specified in relation to the previous copy.

Transform box with 5 copies	Rotate all the boxes with 3 copies	Result

Importing a step file

You can import a step file to create your geometry:

1. Enable model editing and add new element.
2. Select “Import file”.
3. Select the file to upload.
4. Wait until upload has finished.
5. Build the file import or press the “Confirm model changes” button to finalize the changes and update the model and the entity lists.

You can change the offset of the step from the original position and enable extra cleanup of detached geometry from the import settings.

Importing a GDSII file

You can import a GDSII stream format (GDSII) file to create your geometry:

1. Enable model editing and add a new element.
2. Select “Import file”.
3. Select a GDSII file to upload.
4. Wait until upload has finished.

At this point the GDSII file content is parsed and configuration of extrusion of layers can be performed to create the 3D model.

1. Select your base units for layer thickness. All thicknesses can be overridden per layer by providing units after thickness value like 100 nm.
2. Add the layers you want to use from bottom up.
3. Enter layer thicknesses for each layer.
4. Apply the settings and build the element.

Stacked layers

By default all layers are added as relative stacked layers starting from Z level 0. Each new layer is stacked on top of the previous one. Relative layers can be moved up and down in the layers list after they are added.

Absolute layers

If you need to define cutout layers or layers that otherwise span across multiple levels, you can use absolute layers.

1. From layer settings select Convert to absolute
2. Enter thickness and Z start position.

Importing mesh files

Quanscient Allsolve supports gmsh (.msh) and nastran (.nas) mesh formats as direct mesh imports. Adding a mesh works in the same way as other imports but has some limitiations:

• There can be only one mesh for a project.
• You can not add any other shapes or operations before or after a mesh import.
• The simulation mesh item is automatically added and can not be modified in any way after import.

If you want to run the same simulation for multiple different meshes with equal geometry, you can copy the project and replace the mesh import from geometry elements by first removing the old and then adding a new mesh import.

Note

The different meshes should have equal geometry tags.