Unit 2: Application-Specific Modeling Strategies

This unit describes the modeling guidelines for LED and fluorescent lighting systems. Most of the geometric strategies are discussed in Unit 1, so the focus of this unit is primarily on materials and heat loading. There is a short description of model-specific strategy, however, presented in the Fluorescent Applications section.

Materials

• Because buoyancy drives the flow, the air material properties must be allowed to vary.
  • Assign Air, and set the Environment setting to Variable.
• For very thin enclosures, the heat transfer is largely dominated by thermal conduction instead of convection. In certain applications, it is possible to accurately simulate the heat transfer without having to solve for the flow. Create a custom solid material that has the same properties as air. For more about using the "solid air" material...
• If radiation is included, specify emissivity for the fluid and solid materials. (Note that the emissivity specified for the fluid material only applies to the solid and wall surfaces that the fluid touches.)
• Use material devices to simulate objects such as baffles, internal fans, printed circuit boards, compact thermal models, and thermal electric devices. For more about using material devices...

Most solids in lighting applications are either aluminum, ABS, or silicon.

In applications that contain small air gaps that are isolated from larger air regions, a good technique is to simulate the air using a solid material with the properties of air.