Table 3.

Common postprocessing measurements

Parameter	Description	Physical relevance
Stream-trace	Trace of particle(s) within a flow field at a single time	Allows user to observe regions where flow moves toward or away from the walls, where flow stagnates, and where regions of recirculation occur
Wall shear stress (WSS)	Instantaneous measurement of fluid stress near walls, as a result of no slip conditions	Used to observe regions stress along vascular wall is altered, indicating possible regions where endothelium may thicken or thin
Time-averaged WSS (TAWSS)	Average value of WSS along the wall for a cardiac cycle	Indicates direction tangential to the overall flow, used to identify regions where flow reversal persists
Oscillatory shear index (OSI)	Dimensionless quantity indicating direction of WSS in relation to TAWSS	Used to quantify the presence and duration of flow reversal
Relative residence time (RRT)	Dimensionless ratio of OSI and normalized WSS	Provides a characteristic value for locations of flow stagnation and long recirculation periods
Transverse WSS (transWSS)	Quantifies wall shear stress in the direction opposite of flow	Can quantify regions where flow may redirect, or regions where flow needs time to re-orient in the flow direction