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Mesh

• General guidelines:
  • It is often a good idea to start with a coarse mesh to inspect your own input.
  • The level of mesh refinement can significantly affect the results of your simulation. For example, a coarse mesh may sometimes overestimate the air throw from a supply terminal.
  • As a general guideline, when using a typical laptop computer, exceeding three million mesh cells might cause problems. A mesh of 1.5 million cells is typically an easy-to-use model.

Basic settings

• Select base cell size
  • Either drag the bar or enter a value in the box.
• Enter maximum number of refinements level
  • The number of refinement levels corresponds to the number of halvings (i.e., 50% reductions) of the base cell size as the mesh approaches a boundary condition. 
• Check that the inside point (for the mesh) is inside the CFD domain (the air in the room). This point can not, for example, be inside an extruded geometry nor inside an OBJ geometry, nor outside the building.
  Access display of the point via this symbol: 

Mesh refinements

• The maximum number of mesh refinements allowed is six. This also affects mesh volume refinements. 
• The most detailed condition applies when multiple conditions target the same points in the domain.
• It is considered good practice that the size of mesh cells does not change drastically. A reduction in size by half is generally considered acceptable modeling practice. This becomes relevant when the user defines custom local meshing settings.

To create a mesh refinement for a specific volume

• Create an extruded geometry
• Assign it to CFD role Mesh refinement
• Enter a value for the Mesh resolution (meter, m)

Other mesh refinement settings

Click and open "Refinements...".

Number of extrusion layers

Extrusion layers, also called prism or inflation layers, are added in a specified number that determines how many layers are created. In the current CFD version, adiabatic obstructions are excluded from surfaces that receive extrusion layers.
More info in this link.

Extra gap refinement levels

Read the Wiki Help text (press F1) or use this link for information about this feature.

The Introduction Exercise - Mesh

• Open "Refinements..." and set "Number of extrusion layers" to 2. This will apply to all surfaces, except for adiabatic surfaces.

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