Assign Film Coefficient (Convection) Boundary Condition to Exterior Surfaces

A film coefficient (convection) boundary condition simulates exposure to external flow, without actually modeling the air that surrounds it. A higher value of film coefficient would be used to simulate a forced convection situation.

Applying this condition is a little tricky because we need to apply it to all exterior surfaces (including those on the heat sink). The time consuming way is to manually select them. An easier way is to use the "Rubber-band" selection to select all of the surfaces of the heat sink at the same time. The remaining surfaces can then easily be selected manually.

Note: Orient the model using the ViewCube

Click Top on the ViewCube:

viewcube

Select XY (Front) from the Standard Views list.

Note: It is much easier to select the surfaces of the fins if the model is displayed with Perspective Projection disabled. If it is disabled, the model should look like this. Notice that the lower edge of the air gap between each fin is visible:

perspective off

If not, click View > Perspective, and select Orthographic

perspective

Set the Selection Mode to Surface from the Setup tab:

select surface

Position the mouse slightly above and to the left of the heat sink. Hold down the left mouse button, and drag the mouse to the right of the heat sink, just below the air gap between the fins, and release the mouse button. (Do not release the mouse button below the heat sink.)

rubber band select