CashFlow, A Visualization Framework for 3D Flow - Studierstube ...

Related Work2.2. Flow Visualization Algorithms• Time LineA time line is a connection of particle inserted into the flow field at a particulartime. This is very intuitive way to visualize the acceleration of a flow.Defined for unsteady flow only.• Vortex LineA vortex line is a closed line which has the same direction as the vorticity vectorat a particular time. Thus it is the equivalent to a streamline and its velocityvector.Several vortex lines passing through a simple closed curve in space form a vortextube. Figure 2.20 shows several deformed vertex tubes. Note, that vortex linesare created only by a starting turbulence and thus vorticity can only be created inunsteady flow fields.Figure 2.20: Vorticity Skeleton Visualization in 3D. Color denotes velocity magnitude. [SE04].Aside of fluid mechanical definitions rendering a particle trace can be divided intothe following steps:• seed point placementThis is very important if many streamlines are rendered especially in 3D. A commonsolution is a user guided seed point placement[RBJ01] like it was done inthe virtual wind tunnel[KSK01] or the virtual workbench[OWD + 96]. Severalstrategies for seed point placement[VVP00][TB96] and interactive seed pointplacement[RBJ01] have been published.24