Heat Transfer Rate Measure
What is a Heat Transfer Rate measure?
A Heat Transfer Rate measure is used to compute the total rate of heat transferred through an imaginary cut in a model, such as the surface of a volume region or a bonded interface between components.

The imaginary cut is a surface, curve, or edge in a model through which the heat is transferred.

For example, consider the following model.
Use a heat transfer rate measure to compute the heat loads acting on one side of the model and are transferred to the other side of the model. In other words, the heat transfer measure allows you to compute the total heat acting through an imaginary cut on the model, as shown in the next figure.
To define a heat transfer rate measure select surfaces, surface regions, surfaces of a volume region, edges, or assembly components, across which the heat loads act.
The geometric entities you select must define an imaginary cut through your model, across which you want to compute the heat transfer rate. Use surfaces to define imaginary cuts through volumes, and edges and curves to define cuts through shells.
Outward normal vector
If you select a surface, curve, or edge, a purple arrow that indicates the normal direction of the imaginary cut is displayed on the model. Selecting the geometric entity again flips the direction of the arrow and the normal direction of the imaginary cut.
Continuing with the above example, if you want to compute the heat transfer rate of the section of the model on the right side of the imaginary cut, flip the purple arrow so that it points to the left, as shown in the following figure.
Alternatively, if you want to compute the heat transfer rate of the section of the model on the left side of the imaginary cut, flip the purple arrow so that it points to the right.
Note that the directions of the transferred heat depend on the direction of the outward normal of the imaginary cut.
In the assembly mode, you can select a surface that is bonded to a surface of another component.
When you define the heat transfer rate by selection of components, the coincident surfaces of the two components define the imaginary cut. Also, the order in which you select the components determines the orientation of the outward normal of the imaginary cut. The outward normal of the imaginary cut points outward from the first component toward the second component. In other words, the heat transfer rate measure computes the rate of heat transferred from the first component to the second.
For example, if you are working on the following two part assembly.
When defining the heat transferred by selecting components, if you select the blue Ushaped component as the first component and the grey bar as the second component, then the heat transfer rate will be computed as the sum of the heat transferred, through the coincident surfaces between the components, in the direction of the arrows shown in the following figure.
Alternatively, if you select the grey bar component as the first component and the blue Ushaped part as the second component, then the heat transfer rate will be computed as the sum of the heat transferred, through the coincident surfaces between the components, in the direction of the arrows shown in the following figure.