Question : When trying to display the "Flow Arrows" in the terrain, the flow arrows are too small to be visible.
Answer : You can change the "Cell Scale" of the flow arrows from "Element Information". Following are the steps :
1. Select boundary of the terrain.
2. Go to "Element Information". Select the "Flow Arrow" feature. The properties of flow arrows will be displayed. Change the "Cell Scale" to say 50 or as required.