Combined Natural Convection

If a device has internal buoyancy flow as well as external buoyancy flow, the rules described above apply for configuring the external flow domain.

If the device is vented such that the flow passes between the device and the environment, then simply set up the model as described above.

If the device contains flow, but is completely sealed off making it separate from the external flow region, then a pressure condition is required somewhere within the internal fluid region. This is illustrated below for the “Chimney” approach:

Assign the pressure condition to a wetted (internal) surface on a solid part (must be a solid material). This will ensure that the flow cannot pass through this surface, but will satisfy the requirement that the internal region is adequately defined numerically. The requirement of a pressure condition on every completely disjoint fluid region applies to all of the configurations shown above (“Chimney”, “Bucket” and “Hanging”).

Related Topics:

Electronics Cooling Advanced Training

LED and Fluorescent Lighting Advanced Training

External Flow Natural Convection Strategies

Internal Flow Natural Convection Strategies

Example of External Natural Convection

Example of Internal Natural Convection

Mathematical Background of Natural Convection