Geometry

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

To import geometry press Import Geometry button and select the file. Newly imported geometry appears on the Geometries list. Icon on the left from the name determines the type of geometry:

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.

Create Box - creates the cuboid by setting its origin and dimensions in 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.

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 global coordinate system perpendicular to the base. The size of the cylinder is defined by the Length and Radius.

Create Sphere - creates sphere solid geometry. Center defines the location of the sphere and Radius determines its size.

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

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

Geometries default name is associated with the imported file name or created primitives geometry. It is useful to rename the geometry items to be able to better recognize them during further operation. To rename the geometry:

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

car geometry(1) → car_geometry_1_

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. 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:

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

Following options are allowed:

Rotation is the circular movement of an object around the axis of rotation. Movement change the item 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:

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

Following options are allowed:

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, operation can cause:

Scaling factor equal 0 is not allowed (due to it cause projection). Non-uniform scaling changes the shape of the object.

SimFlow uses SI 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 model is defined in mm, it has to be scaled to the meter uniformly by scaling factor 0.001. Scale is not available for cylinder and sphere primitives.

To scale the geometry:

When you apply Scale operation a Scale Geometry panel will appear.

Following options are allowed:

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

To Check the geometry:

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 point onto base of triangle. These clean operations are to prepare the geometry for meshing.

To Clean the geometry:

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

To Split geometry faces:

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

Extract Features operation will generate edges for an STL where the angle between two triangles is smaller than 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:

When you apply Extract Features operation to a geometry a Extract Features panel will appear.

Following options are allowed:

Duplicate - copy the geometry and paste as a new one. In that way, 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:

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

To replace the geometry:

Delete - removes the selected geometry from the simulation.

To delete the geometry:

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

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

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

Properties of imported geometry refers to the Surface Quality level. Due to the mesh input geometry is always STL format, all others geometries should be converted to the STL. Surface Quality determines by the density of surface division into triangles. It has an impact on the quality of meshed surface, however to high level of surface quality significantly extends the meshing process.

Three level of quality are available in order of accuracy:

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

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

It is possible to edit 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 Delete button is visible. Any changes to the face selection in graphics window will cause two additional edit buttons to appear: