**3. Results and discussion**

#### **3.1 Velocity profiles along the cardiac cycle**

**Figure 3** illustrates the velocity profiles measured along the center of the artery for both CFD and FSI simulations, in two different phases of the cardiac cycle: systole (0.4 s) and diastole (0.58 s).

Looking at the results in **Figure 3**, it can be observed that the estimated velocity profiles are similar for both CFD and FSI modeling. Moreover, as expected, during diastole (**Figure 3b**) the velocities measured are higher than during systole (**Figure 3a**). This happens because, during systole, the coronary arteries are compressed by the contraction of the myocardium, and so, most of the coronary flow occurs during diastole, where the flow increases. In addition, the maximum velocities in both cases are measured in the stenosis throat (*x* = 0 mm) as observed by other investigations [15, 27].

It is also noted that the velocity is overestimated in the CFD model, particularly at and upstream of the stenosis throat. This is expected because the deformation of the elastic model provides a larger volume for the blood flow through and, as the inflow rate is equal for both models, naturally, the velocities will be higher when a rigid wall is considered. Downstream of the stenosis, at an *x* coordinate of approximately 10 mm, the velocity is higher for the FSI case, which indicates that the pressure drop at the stenosis creates zones of low pressure, which contracts the artery, and forces the flow to accelerate. In this case, it is thus observed the effect of artery compliance, which allows a steadier supply of flow despite the variable nature of the cardiac cycle.

**Figure 3.** *Axial flow velocity profiles at the center line drawn across the artery at (a) systole and (b) diastole.*

*Comparison of CFD and FSI Simulations of Blood Flow in Stenotic Coronary Arteries DOI: http://dx.doi.org/10.5772/intechopen.102089*
