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Documentation

Geometry Primitives

Geometry primitives are primitive shapes that can be used for multiple purposes during the simulation setup. If you want to capture a part of the CAD geometry to apply certain simulation settings like additional mesh refinement, presence of a power or a momentum source, monitoring result controls then creating primitive shapes and assigning them comes handy. In this document, we will go through the types of primitives supported by SimScale, as well as their applications.

Creating Geometry Primitives

Geometry primitives can be created from within the corresponding simulation settings that may require them. For e.g., while creating advanced concepts (like passive scalar sources) the settings panel gives the user an opportunity to create primitive shapes to which the advanced concept can be applied.

geometry primitive creation
Figure 1: Creating geometry primitive shapes while defining the settings inside the simulation tree, advanced concept (left), meshing (right).

They can also be created by clicking the ‘+’ button next to Geometry Primitives under the scene tree.

geometry primitive
Figure 2: Creating geometry primitive shapes from under the scene tree on the right of the Workbench.

Types of Geometry Primitives

Cartesian Box

A Cartesian box is specified with the minimum and maximum box coordinates in the x, y, and z-directions. The figure below shows a cartesian box for a mesh region refinement.

cartesian box geometry primitive
Figure 3: Cartesian box used for a region refinement. In external aerodynamics, it’s particularly helpful to capture the wake.

Note

Geometry primitives can also be created using the pick method. Select the Pick from the viewer icon pick position button to choose a point from within the simulation domain which will act as the corresponding coordinate, for e.g. minimum coordinate for the cartesian box or the centre for the sphere geometry primitive.

Sphere

Spheres can be used for mesh refinement or as spherical power sources. To create a sphere, one has to specify its center coordinates, as well as the radius.

sphere geometry primitives
Figure 4: Sphere to specify an absolute power source

Cylinder

Cylinders are often used for mesh refinements. Another common application is to create momentum sources, which mimic the effects of a fan.

To specify a cylinder, the user needs to input a point of reference for the base of the cylinder. By adjusting the axis, one can determine the direction and length of the cylinder. Finally, the user should also define the radius for the cylinder.

cylinder geometry primitive in simscale
Figure 5: Using a cylinder placed inside a pipe to define a momentum source

Point

Points are mostly used to create probe point result controls. A chain of points can be created to obtain a profile of the simulation variables across a line. The center coordinates are sufficient to set up a point geometry primitive.

static simulation of a bearing block
Figure 6: Static simulation on a bearing block. A probe point is set for a point data result control.

Local Slice

Local slices are used in the Pedestrian wind comfort (PWC) and Incompressible (LBM) analysis types. They are planes (2D) that are placed in the domain for data visualization. For more information about local slices, please check this page.

local slice geometry primitive
Figure 7: Local slice geometry primitive for contours visualization

List of Applications

Find below a list of applications where geometry primitives can be used, as well as the available types:

Last updated: August 3rd, 2022

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