Add CFD Boundary

 

When at surface level you can add a CFD boundary in much the same way as a window or any other opening . Please refer to the instructions for the Draw window tool for details on the process of drawing the CFD boundary.

Note: An important difference with placing CFD supply and extract boundaries compared with other openings such as windows, is that their edges must not coincide with parent surface edges. The CFD boundary should be separated from the surface edges by a distance of at least 0.1 m.

You should also ensure that there are at least three grid cells between a supply boundary and an obstruction (such as a wall, component or assembly), otherwise, during simulation, the flow can ‘lock’ and the mass residual will not converge.

 

After selecting the Add CFD boundary tool, the boundary settings are displayed on the Drawing options data panel. You can select the required boundary type from the Boundary type drop list. The following boundary types are available for surfaces of all orientations:

 

 

The following additional boundary types for multi-directional diffusers are available for ceiling and other downward-facing surfaces only:

 

 

Various settings are available depending on the boundary type:

1-Supply:

 

Note: In the case of non-orthogonal supply diffusers, the minimum discharge velocity can only be guaranteed if the diffuser has no tilt in the z-dimension (i.e. it has a non-orthogonal azimuth but zero tilt).

Note: Supply diffuser discharge angles only apply to orthogonal diffusers, i.e. to diffusers aligned with the grid. For diffusers placed on non-orthoganol diffusers the discharge angles simulated will be incorrect.

2–Four-way

 

3–Two-way

 

4–Extract

 

5–Temperature

 

6– Flux

 

Note: You can add all types of CFD boundary conditions to zone surfaces, but only supply and extract CFD boundaries can be added to component block surfaces.