CST2013: Mesh Properties (Hexahedral)

Simulation: Mesh Global Properties

Through the Mesh Properties dialog box the mesh generation can be controlled. The settings of this dialog box influence the mesh generally, regardless if the automatic mesh generation is switched on or off. If the automatic mesh generation is switched on, its behavior can be controlled by the Special Mesh Properties dialog box (Home: Mesh Global Properties Specials...).

Note: The active mesh type refer merely to the mesh preview. A change of the solver method will change the active mesh type.

Mesh density control frame

Lines per wavelength: This value is connected to the wavelength of the highest frequency set for the simulation. It defines the minimum number of mesh lines in each coordinate direction that are used for a distance equal to this wavelength.

This sets the spatial sampling rate for the signals inside of your structure. This setting has a strong influence on the quality of the results and on the calculation time. Increasing this number leads to a higher accuracy, but unfortunately also increases the total calculation time.

A good compromise between calculation time and the achievable accuracy is the default value of 10.

Lower mesh limit (LML): This setting allows you to define the maximum mesh step to be used for the mesh creation, regardless of the setting in Lines per wavelength. The maximum step width of the mesh is determined by dividing the smallest face diagonal of the bounding box of the calculation domain by this number with a factor of sqrt(3.0):

Maximum Step Width = Smallest Box Face Diagonal / LML / sqrt(3.0)

Mesh line ratio limit: The calculation time is highly dependent on the chosen mesh. Not only the absolute number of mesh cells used is relevant, but also the distance between two mesh lines. The smallest distance existing in a mesh directly influences the width of the time steps usable in the simulation. The smaller the smallest distance, the smaller the time step and the longer it takes to simulate a period of the electromagnetic fields.

For some structures the automatic mesh generator creates mesh lines that are very close to each other. For a very accurate simulation these mesh lines might be necessary, but the resulting calculation time might be unacceptable. To avoid such a situation you can define this ratio limit. It forces the automesh module not to overcome an absolute ratio between the highest and the smallest distance between mesh lines.

The default value of 10 is very often a good compromise to start with.

Be aware that this setting holds for the manual mesh as well! If you set two fixpoints too close to another, you might not get mesh lines through these fixpoints although expected.

Smallest mesh step

Sets the smallest mesh step defined by the structure's geometry. However, if a smaller value is defined in the Local Mesh Properties (Hexahedral) or a mesh step refinement due to a shorter wavelength inside dielectric material is needed, the particular minimum is used.

Automatic mesh generation

Switches the automatic mesh generation on or off. That means if the automatic mesh generation is switched off then the current mesh controls are fixed and the mesh of the  last automatic generated mesh is used. Afterwards only single mesh lines can be removed or added.

Specials...

This button leads to a dialog box, that allows you control the automatic mesh generator.

Mesh summary frame

The values shown in this frame are only for information purposes. You cannot edit them.

Min. mesh step: The smallest mesh step used.

Max. mesh step: The biggest mesh step used.

Nx / Ny / Nz: These fields shows you the number of mesh lines in each coordinate direction used in the current mesh.

Meshcells: This number is the total number of mesh cells used in the current mesh. It is directly connected to the simulation time and the amount of memory needed.

OK

Accepts the changes and closes the dialog. If changes were made, the mesh will be updated.

Apply

Stores the current settings. The dialog box open remains open.

Update / Force LF Mesh / Force HF Mesh

Update

In cases where the determination of the mesh needs some time (staircase mesh for instance) it is not updated automatically by the "Apply" or the "OK" button. Press this button to force the mesh to be updated.

Force LF Mesh / Force HF Mesh

If a problem type has been changed from "High Frequency" to "Low Frequency" or vice versa you will be asked if the mesh should be updated according to the new problem class. Pressing this button may delete existing results.

Cancel

Closes this dialog box without performing any further action.

Help

Shows this help text.

See also

Mesh View, Automesh Properties,  Frequency Range. Simplify Model, Which mesh to use, Hexahedral Mesh