Fig. 7

Illustration of six different types of flow patterns which are extracted from a 3D coronary model and applied in a coronary centerline for the computation of blood flow. Four flow patterns are in connection with geometric structure, and the other two occur as blood flows. \(d\) represents the diameter of vessel, \(A\) represents the cross-sectional area, and \(P\) is the pressure. In particular, \(\theta_{{\text{b}}}\) is defined as the amount of change in the angle of directional vector of centerline. \(\theta_{{\text{c}}}\) and \(\theta_{{\text{e}}}\) are, respectively, representing the changing degrees of the vessel diameter with constriction and expansion, which is determined by the diameters of two adjacent points and the distance between them