Specify Automatic Settings

• Level of Initial Mesh . Governs the number of Basic Mesh (Global Mesh) cells and the default procedure of mesh refining in the model’s narrow channels. A higher level produces more fine cells but it will take greater CPU time and require more computer memory.

• Minimum Gap Size . Allows you to specify the Minimum Gap Size value to discern diminutive geometry that is not automatically recognized by Flow Simulation. This value have an influence on a characteristic cell’s size and together with Level of initial mesh govern the total number of cells generated in the computational mesh.

  Flow Simulation calculates the default minimum gap size using information about the overall model dimensions, the Computational Domain, and faces on which you specify Conditions and Goals. However, this information may be insufficient to recognize relatively small gaps. All these factors may cause inaccurate results. In these cases, the Minimum Gap Size must be specified manually. The manually specified value is retained if you modify the model or Flow Simulation project.

  Tip

  Prior to starting the calculation, it is recommended to check the geometry resolution to ensure that small features will be recognized.

  Use Tools > Flow Simulation > Project > Summary  to observe the Minimum Gap Size.

  Tip

  If you set boundary conditions, surface goals, or modify the model or Computational Domain, this characteristic size may change.

  Click Tools > Flow Simulation > Project > Rebuild  to update the minimum gap size.

  Note:

  Flow Simulation generates the Basic Mesh in order to have a minimum of two cells per the specified Minimum Gap Size. The number of cells per the Minimum Gap Size non-linearly depends on the Level of initial mesh and cannot be less than two.

  If you specify a very small value of the Minimum Gap Size and a high result resolution, the number of mesh cells will dramatically increase.

  As well as cell size (i.e. number of computational mesh cells), this option governs the Small solid features refinement level and Curvature refinement level (see “Manual Settings for Global Mesh” for details).

• Minimum Wall Thickness . Allows you to specify the Minimum Wall Thickness that governs the resolution of the sharp edges such as tips of thin fins. This value does not influence the meshing if it is equal to or greater than the Minimum gap size.

  Flow Simulation calculates the default minimum wall thickness using information about the model size, the Computational Domain, volume sources, initial conditions, surface sources and surface goals.

  Note:

  In case of internal analyses, boundaries between internal flow and ambient space are always resolved properly because distinguishes the internal flow volume and ambient space.

  Tip

  If the Minimum Wall Thickness option is unavailable, select Show for the Show/Hide wall thickness option under General Options in the Options dialog (see “Options”).

• Ratio Factor  (available for an External analysis only). Allows you to adjust the ratio of cell sizes outside the internal control planes.

  By default, the internal control planes are automatically placed around the model. The cell sizes inside the internal control planes are uniform, and they are changed gradually along each direction outside the internal control planes. The default ratio of the bigger to the smaller cell size outside the internal control planes is defined automatically and can be multiplied by the specified constant (Ratio Factor).

• Uniform Mesh (available for an External analysis only). When checked, disables the Ratio Factor option and sets the ratio of cell sizes to 1 for all control planes.

• Advanced channel refinement. If you have selected this option, the default Maximum Channel Refinement Level is set greater by one than the Tolerance Level (see “Advanced Channel Refinement” for details). Otherwise, it depends on the Level of initial mesh and cannot be greater than four, resulting in the restriction of the minimum size of cells across the model’s flow passage in the normal-to-solid/fluid-interface directions.

• Show basic mesh. Allows you to see the obtained basic mesh immediately on the model.

  When this option is checked, the Show Cell Size tool becomes available (see “Show Cell Size” for details).

  Tip

  To access the Show basic mesh box from the Ribbons, click Tools > Flow Simulation > Mesh > Show basic mesh.

Maximum Height of Slots to Close . Allows you to specify the Maximum Height of Slots to Close value to fill slots which height is less than the specified value with the Solid closest to the slot.