# Geometry

Source: https://help.sim-flow.com/documentation/panels/geometry
Last updated: 2026-10-14

## Introduction

![geometry panel](https://help.sim-flow.com/documentation/panels/images/geometry/geometry-panel.png)

The **Geometry** panel allows users to add, delete and manipulate geometry. All geometries are listed and sorted alphabetically. Editing options are available after selecting a geometry from the list.

## Add Geometry

![add geometry](https://help.sim-flow.com/documentation/panels/images/geometry/add-geometry.png)

New geometry can be added using buttons available in the **Add New** bar below the **Geometries** list. There are two available options to add a geometry:

- Import Geometry
- Create Geometry

### Import Geometry

![load geometry](https://help.sim-flow.com/documentation/panels/images/geometry/load-geometry.png)

The **Import Geometry** option allows for importing geometry from external formats. Geometry can be prepared in the external CAD software and exported in one of the supported formats. Currently, supported geometry formats are:

- STL (recommended)
- OBJ
- STEP
- IGES
- BREP

To import geometry, press the **Import Geometry** button and select the file. Newly imported geometry appears on the **Geometries** list. The icon to the left of the name determines the type of geometry:

- ![icon stl](https://help.sim-flow.com/documentation/panels/images/geometry/icon-stl.png) STL geometry
- ![icon shell](https://help.sim-flow.com/documentation/panels/images/geometry/icon-shell.png) Shell (surfaces) geometry
- ![icon solid](https://help.sim-flow.com/documentation/panels/images/geometry/icon-solid.png) Solid geometry

#### Imported Geometry Units (only STL geometry)

![imported geometry unit](https://help.sim-flow.com/documentation/panels/images/geometry/imported-geometry-unit.png)

Every geometry format, except STL, stores information about the units in which the geometry was created. For the STL geometry, the unit needs to be confirmed during the import operation. Based on the selected unit, the model will be scaled to the base SI unit - meter. If the unit is unknown, the *Geometry size* preview should help to choose the right one. The *Geometry size* displays the current overall size of the geometry being imported (or geometries if multiple files are selected).

To define the unit:

- 1 Select the unit of the imported geometry
- 2 Control the size of the bounding box
- 3 Confirm with the **OK** button

### Create Geometry

![create geometry](https://help.sim-flow.com/documentation/panels/images/geometry/create-geometry.png)

Three types of primitive geometries can be created directly in SimFlow. These primitive geometries are usually used as tools for marking mesh cells for refinement or custom solution initialization value.

![icon box](https://help.sim-flow.com/documentation/panels/images/geometry/icon-box.png) **Create Box** - creates the cuboid by setting its origin and dimensions in the global coordinate system. The **Origin** defines the coordinate of the first corner of the box. The **Dimensions** determine the size of the box measured in the direction of the positive axes of the global coordinate system.

![add box](https://help.sim-flow.com/documentation/panels/images/geometry/add-box.png)

![icon cylinder](https://help.sim-flow.com/documentation/panels/images/geometry/icon-cylinder.png) **Create Cylinder** - creates the cylinder geometry by setting its origin and dimensions. The **Origin** determines the position of the base center. The cylinder **Axis** is defined by the vector in the global coordinate system perpendicular to the base. The size of the cylinder is defined by the **Length** and **Radius**.

![add cylinder](https://help.sim-flow.com/documentation/panels/images/geometry/add-cylinder.png)

![icon sphere](https://help.sim-flow.com/documentation/panels/images/geometry/icon-sphere.png) **Create Sphere** - creates sphere solid geometry. **Center** defines the location of the sphere and **Radius** determines its size.

![add sphere](https://help.sim-flow.com/documentation/panels/images/geometry/add-sphere.png)

## Geometry Options

![geometry list](https://help.sim-flow.com/documentation/panels/images/geometry/geometry-list.png)

After successfully importing or creating a new geometry, the program will add a new entry to the **Geometries** list. This entry allows users to manipulate and interact with the geometry.

The icon to the right of the name ![icon options](https://help.sim-flow.com/documentation/panels/images/geometry/icon-options.png) expands the available geometry options. Currently, supported context options are:

- **Hide**/**Show** - changes visibility
- **Rename** - allows you to change the geometry name
- **Translate** - allows you to move the geometry
- **Rotate** - allows you to rotate the geometry around an arbitrary axis
- **Scale** - allows you to scale geometry
- **Check** (STL only) - performs basic checks of the geometry
- **Clean** (STL only) - removes baffles, sliver faces, collapses small edges, etc.
- **Split** (STL only) - splits geometry into patches along sharp corners
- **Extract Features** (STL only) - generates edges on sharp corners
- **Duplicate** - creates a new geometry identical to the current
- **Replace** - option for replacing the current geometry with a new one
- **Delete** - deletes the geometry

### Select / Deselect

![select](https://help.sim-flow.com/documentation/panels/images/geometry/select.png)

- **Select**
  To select the geometry, move the mouse over an item and click the right mouse button `RMB`. Selected geometry name will be highlighted in gray.
- **Multi-Select**
  Hold the `Ctrl` key and click on the next items for multi-selection. Select the first item, then, holding the `Shift` key, click the second item to select all geometries between these two items.
- **Deselect**
  To deselect the item, hold the `Ctrl` key and click `RMB` on the geometry name. To clear the selection, press the `Esc` key on the keyboard or click on the free space outside the geometry list.

### Hide / Show

![hide show options](https://help.sim-flow.com/documentation/panels/images/geometry/hide-show-options.png)

In SimFlow, there is a possibility to hide or show geometries in the 3D graphics window. Each item could be hidden (or shown) using options on the geometries list. To hide or show geometry in a 3D window:

- 1 Expand the list of options next to the item
- 2 Select **Hide** or **Show** option or
- 3 Click the **Toggle Visibility** icon next to the item name
- 4 The icon of the hidden element will be grayed out

When you click the icon the second time, the respective geometry will be shown in the graphics window and the icon will again become colored.

### Rename

![rename geometry](https://help.sim-flow.com/documentation/panels/images/geometry/rename-geometry.png)

The geometry’s default name is associated with the imported file name or created primitive geometry. It is useful to rename the geometry items to be able to better recognize them during further operations. To rename the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Rename**
- 3 Type a new name and approve by pressing the `Enter` key
- 4 An alternative approach is to double-click on its name and enter a new one
  To reject the changes, press the `Esc` key before approving

Be aware that spaces and other special characters are not allowed. All of them will be replaced by an underscore char during the typing, e.g.:

`car geometry(1) → car_geometry_1_`

### Translate

![translate](https://help.sim-flow.com/documentation/panels/images/geometry/translate.png)

Translation is a movement that changes the position of an object. Each body point is transformed from its initial position to its final position using a translation vector. The translation vector is the same for each point of the object. After translation, the orientation of the body in space is unaltered.

To **Translate** the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Translate**

When you apply the **Translate** operation, a **Translate Geometry** panel will appear.

![translate options](https://help.sim-flow.com/documentation/panels/images/geometry/translate-options.png)

The following options are allowed:

- 3 Geometries can be added or removed from the transformation list
- 4 **Translation Vector** which defines the distance by which the geometry will be moved. The vector is defined in the global coordinate system
- 5 To approve the operation, click **Translate**

#### Multiple Geometries Translation

![translate multiselect](https://help.sim-flow.com/documentation/panels/images/geometry/translate-multiselect.png)

To translate multiple geometries, there is an alternative approach:

- 1 Select geometries to translate (holding `Ctrl` or `Shift` key, select 2 or more components)
- 2 Select **Translate Geometries**

### Rotate

![rotate](https://help.sim-flow.com/documentation/panels/images/geometry/rotate.png)

Rotation is the circular movement of an object around the axis of rotation. The movement changes the item’s radial orientation relative to a common point - **Origin** - which lies within the **Axis** of rotation. Rotation is not available for **box** primitive geometry.

To rotate the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Rotate**

When you apply the **Rotate** operation, a **Rotate Geometry** panel will appear.

![rotate options](https://help.sim-flow.com/documentation/panels/images/geometry/rotate-options.png)

The following options are allowed:

- 3 Geometries can be added or removed from the transformation list
- 4 **Origin** - fixed point of the rotation
- 5 **Axis** - direction around which the rotation will be performed
- 6 **Angle** - angle of the rotation
- 7 To approve the operation, click **Rotate**

#### Multiple Geometries Rotation

![rotate multiselect](https://help.sim-flow.com/documentation/panels/images/geometry/rotate-multiselect.png)

For multi-selection, there is an alternative approach to rotate geometries:

- 1 Select geometries to rotate (holding `Ctrl` or `Shift` key, select 2 or more components)
- 2 Select **Rotate Geometries**

### Scale

![scale](https://help.sim-flow.com/documentation/panels/images/geometry/scale.png)

Scaling is a transformation in which the coordinates of each point belonging to an object are multiplied by a relevant factor. In a general approach, scaling is to change the size of an object. However, the scaling operation also changes the position of the object in the global coordinate system. Depending on the scaling factors, the operation can cause:

- enlargement - when the scaling factor is larger than 1
- reduction - when the scaling factor is positive and smaller than 1
- reflection - when the scaling factor is negative

A scaling factor equal to 0 is not allowed (because it causes projection). Non-uniform scaling changes the shape of the object.

SimFlow uses [SI units](https://en.wikipedia.org/wiki/International_System_of_Units), so the length is defined in meters. If the imported geometry is defined in other units, it is important to scale the model to the meter e.g.: if the model is defined in mm, it has to be scaled to the meter uniformly by a scaling factor of 0.001. Scale is not available for **cylinder** and **sphere** primitives.

To scale the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Scale**

When you apply the **Scale** operation, a **Scale Geometry** panel will appear.

![scale options](https://help.sim-flow.com/documentation/panels/images/geometry/scale-options.png)

The following options are allowed:

- 3 Geometries can be added or removed from the scale list
- 4 To scale uniformly check the **Uniform** option
- 5 Define **Scaling Factors** for each of the directions
- 6 To approve the operation, click **Scale**

#### Multiple Geometries Scaling

![scale multiselect](https://help.sim-flow.com/documentation/panels/images/geometry/scale-multiselect.png)

**Scale** can be applied to multiple geometries. To scale a few geometries at a time:

- 1 Select geometries to scale (holding `Ctrl` or `Shift` key, select 2 or more components)
- 2 Select **Scale Geometries**

### Check

![check](https://help.sim-flow.com/documentation/panels/images/geometry/check.png)

The **Check** option is used for checking the geometric and topological quality of a surface. The algorithm checks whether each edge connects with exactly two faces and all points are inside the geometry bounding box. The **Check** option is available for imported geometries.

To **Check** the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Check**
- 3 The **Check** summary is printed in a **Console**

![check console](https://help.sim-flow.com/documentation/panels/images/geometry/check-console.png)

### Clean

![clean](https://help.sim-flow.com/documentation/panels/images/geometry/clean.png)

The **Clean** option is dedicated to the STL geometry formats. It fixes the surface by removing baffles, collapsing small edges by removing triangles and converting sliver triangles into split edges by projecting a point onto the base of the triangle. These clean operations are to prepare the geometry for meshing.

To **Clean** the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Clean**
- 3 The **Clean** summary is printed in a **Console**

![clean console](https://help.sim-flow.com/documentation/panels/images/geometry/clean-console.png)

### Split

![split](https://help.sim-flow.com/documentation/panels/images/geometry/split.png)

The split operation allows you to divide faces into smaller parts. This option is available for the STL format, where the imported geometry is usually a single face and you have to define different boundary conditions on different faces. Splitting the geometry will separate faces based on the limit angle between them.

To **Split** geometry faces:

- 1 Expand the list of options next to the item
- 2 Select **Split**

![split options](https://help.sim-flow.com/documentation/panels/images/geometry/split-options.png)

When you apply the **Split** operation to a geometry, a **Split Geometry** panel will appear with the following options:

- 3 **Split Angle** - whenever the angle between two STL triangles \(\alpha\) (picture below) is smaller than this value, the two triangles will be put into separate faces. Characteristic values of the split angle:
  - 0 degrees - no edges selected
  - 180 degrees - all edges selected
  - 120 degrees - default angle

![split angle](https://help.sim-flow.com/documentation/panels/images/geometry/split-angle.png)

- 4 **Remove After Split** - input to specify whether the original unsplit geometry should be removed after the operation
- 5 **Create Single Geometry** - input to specify whether the split STL faces should be put into a single geometry or each should be placed in a separate geometry
- 6 To approve the operation, click **Split**

### Extract Features

![extract features](https://help.sim-flow.com/documentation/panels/images/geometry/extract-features.png)

**Extract Features** operation will generate edges for an STL where the angle between two triangles is smaller than the **Maximum Feature Angle**. The edges will be generated, loaded and displayed in the graphics window. These edges will be later used by the meshing algorithm to accurately resolve sharp features of the geometry.

To **Extract Features**:

- 1 Expand the list of options next to the item
- 2 Select **Extract Features**

When you apply the **Extract Features** operation to a geometry, an **Extract Features** panel will appear.

![extract features options](https://help.sim-flow.com/documentation/panels/images/geometry/extract-features-options.png)

The following options are allowed:

- 3 **Maximum Feature Angle** - define the limit angle between surface normals below which the edges are marked for extraction. Characteristic values of the parameter:
  - 0 degrees - no edges selected
  - 180 degrees - all edges selected
  - 120 degrees - default angle
- 4 To approve the operation, click **Extract**

### Duplicate

![duplicate](https://help.sim-flow.com/documentation/panels/images/geometry/duplicate.png)

**Duplicate** - copy the geometry and paste as a new one. In that way, a new geometry is created identical to the current one. The new component has an automatically generated name - a suffix with a number is added to the original name.

To duplicate the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Duplicate**
- 3 New geometry will appear in the geometries list

### Replace

![replace](https://help.sim-flow.com/documentation/panels/images/geometry/replace.png)

**Replace** - option for replacing the current geometry with another one. The option is available only for imported geometry. The current geometry will be removed and a new geometry will be imported instead of the old one.

To replace the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Replace**
- 3 Point to the new geometry and press **OK**

### Delete

![delete](https://help.sim-flow.com/documentation/panels/images/geometry/delete.png)

**Delete** - removes the selected geometry from the simulation.

To delete the geometry:

- 1 Expand the list of options next to the item
- 2 Select **Delete**

When you apply the **Delete** operation to a geometry, it is not immediately removed but is put into the delete queue. The current state of the delete queue is displayed at the bottom of the panel.

![img 595417c6d451d](https://help.sim-flow.com/documentation/panels/images/geometry/img-595417c6d451d.png)

Any geometry in the delete queue can be restored by clicking on the respective button. However, every time you leave the **Geometry** panel, the queue is cleaned and the geometries are deleted permanently.

#### Multiple Geometries Deleting

![delete multiple geometries](https://help.sim-flow.com/documentation/panels/images/geometry/delete-multiple-geometries.png)

To delete multiple geometries at once:

- 1 Select the items from the geometries list
- 2 Click the **Delete** button at the top bar

## Boolean Operations

![boolean](https://help.sim-flow.com/documentation/panels/images/geometry/boolean.png)

Boolean operations are used for combining geometries in various ways to create new, more complex geometric forms. Boolean operations are available for solid, shell and primitive geometry except the STL format geometry. While selecting two or more geometries from the list, Boolean operation buttons will be displayed on a title bar. Currently, the following operations are available:

- 1 **Unite** - items are combined into a single geometry. The union of two geometries A and B is the region in geometry A, B or in both A and B. The union operation is commutative and the order of selection does not matter.

![unite](https://help.sim-flow.com/documentation/panels/images/geometry/unite.png)

- 2 **Intersect** - the result is the common part of the geometry. The intersection of two geometries A and B is the region inside volume A that is also inside volume B. The intersection operation is commutative and the order of selection does not matter.

![intersect](https://help.sim-flow.com/documentation/panels/images/geometry/intersect.png)

- 3 **Subtract** - all other objects are subtracted from the first object. The difference of two geometries A and B is the part of the geometry A volume that does not belong to B. The order of selection matters for Boolean subtract.

![subtract](https://help.sim-flow.com/documentation/panels/images/geometry/subtract.png)

## Geometry Properties

![properties](https://help.sim-flow.com/documentation/panels/images/geometry/properties.png)

**Properties** - describe the features that allow you to edit the geometry in SimFlow. For the geometry created in SimFlow, it is possible to change its dimension and origin. For the imported geometry, it allows you to edit import parameters. The Properties option is not available for STL items.

To find this option:

- 1 Place the pointer over a row in the geometry list and click the **Properties** icon

### Edit Primitives Geometry

![properties primitives](https://help.sim-flow.com/documentation/panels/images/geometry/properties-primitives.png)

The **Properties** button activates the geometry edit mode, which shows the geometry properties panel. It also changes the geometry view in the 3D window to enable editing. Note that currently, you will be able to edit properties of primitive geometries and this option will not be available for geometries imported from external files.

### Edit Imported Geometry

![properties imported](https://help.sim-flow.com/documentation/panels/images/geometry/properties-imported.png)

**Properties** of an imported geometry refer to the **Surface Quality** level. Because the mesh input geometry is always in STL format, all other geometries should be converted to the STL. Surface Quality determines the density of surface division into triangles. It has an impact on the quality of the meshed surface. However, too high a level of surface quality significantly extends the meshing process.

Three levels of quality are available in order of accuracy:

- **Normal**
- **Fine**
- **Very Fine**

It is good practice to gradually increase the quality level to achieve a satisfactory surface quality at a low numerical cost.

## Face Groups

![geometry faces](https://help.sim-flow.com/documentation/panels/images/geometry/geometry-faces.png)

A **Face Group** is a set of surfaces belonging to one geometry separate from other faces to assign different properties. It is usually used to assign boundary conditions or set special mesh attributes.

**Geometry Faces** button is visible when the pointer is placed over a row in the geometry list. It activates face edit mode which shows the **Face Groups** panel and switches the 3D geometry selection mode to allow face selection.

### Create Face Group

![geometry faces options](https://help.sim-flow.com/documentation/panels/images/geometry/geometry-faces-options.png)

All geometry faces are initially put into the default group. To extract a group of faces, for example to define a different boundary condition, a separate face group needs to be defined. In the **Geometry Faces** panel, the following options are available:

- 1 List of current face groups. Face Group can be renamed by double-clicking on the name. However, the default group cannot be renamed.
- 2 **Extract Group** *(available only for STL geometries)* button allows you to extract face group into a separate STL geometry
- 3 **Clear Selection** button allows you to clear group list and graphic face selection
- 4 **Create New Face Group** button allows you to add new face groups to the list using one of two options:
  - 5 **Create Empty Group** allows you to create an empty group and add faces to it later
  - 6 **Create Group From 3D Selection** allows you to select some faces in the graphics window and put them into a newly created group

[Video](https://help.sim-flow.com/documentation/panels/images/geometry/how-to-create-face-group.mp4)

### Editing Face Group

![img 595411a2ec61d](https://help.sim-flow.com/documentation/panels/images/geometry/img-595411a2ec61d.png)

It is possible to edit a non-default face group after it is selected in the **Face Groups** list. When a face group is selected, all its faces are highlighted in the graphics window. When a face group is selected, only the **Delete** button is visible. Any changes to the face selection in the graphics window will cause two additional edit buttons to appear:

- 1 **Update Face Group** button will cause the content of the currently selected group to be equal to the selected faces in the graphics window
- 2 **Reset Face Group** button will reset the graphics window face selection to be equal to the group content
- 3 **Delete** button will remove an existing face group. If the removed group contained some faces, they will be moved into the *default* group.