Visualizing 3D fluid flow fields presents a challenge to scientific visualization, mainly because no natural visual representation of 3D vector fields exists. We can readily recognize geometric objects, color, and texture: unfortunately for computational fluid dynamics (CFD) researchers, vector fields are harder to grasp. Thus, we must construct simplified representations that human observers can understand. Simplification means focusing on relevant aspects of the flow. This offers many options, making a wide variety of flow visualization techniques both feasible and desirable. This article presents an overview of three different visualization techniques developed in the Netherlands. The three useful techniques for visualizing 3D flows are:...