Boundary Conditions for Internal CFD Analyses

Internal boundary conditions can be defined in three ways:

1. Surface temperatures can be defined for all zone surfaces including windows and other openings.
2. Zone surface boundary conditions including supply diffusers, extract grilles, temperatures and heat fluxes can be added in the form of surface patches using a similar method to that used for adding windows and doors.
3. Component blocks and component assemblies can be defined as temperature or heat flux boundaries or they can also have boundary condition patches added as described above for Zone surfaces.

In all cases the CFD boundary conditions can be edited on the CFD Model data tab.

Default Wall and Window Temperatures

All zone surfaces within a model have default wall and window boundary temperatures. These boundary temperatures are inherited from the building level down to the zone surface level and may be set at any intermediate level. This mechanism provides a convenient method for defining wall and window temperature boundary conditions throughout a building model in the absence of imported EnergyPlus boundary data.

Default inside and outside wall and window boundary temperatures can be accessed under the CFD Boundary header on the CFD tab.

Zone and Component Block Surface Boundaries

Supply diffusers, extract grilles, temperature and heat flux patches can be added to zone and component block surfaces using the Add CFD boundary tool.

To add a surface boundary, move down to the surface on which you want to locate the boundary, either by selecting it from the model navigator or by navigating to it in the Edit screen. At the surface level, you can then select the Add CFD boundary tool from the toolbar.