Influence of Jet Orientation on Energy Dissipation and Pressure Loss in a Simplified Aortic Model

The orientation of aortic jets is known to vary significantly in patients with aortic stenosis or following valve replacement procedures, leading to changes in downstream flow structures and pressure loss. While previous studies have highlighted the importance of jet misalignment, the isolated effect of jet orientation on pressure loss under constant geometric orifice area ( GOA ) conditions remains poorly quantified, and the dominant mechanisms governing this relationship are still not fully established. In this study, we systematically investigate the effect of jet orientation on pressure loss using a simplified aortic model under steady flow conditions, where GOA is strictly maintained constant to isolate orientation effects. A range of jet orientations was examined experimentally, and measurable differences in pressure loss were observed across cases, with a maximum variation of approximately 0.2 mmHg under identical flow conditions. To examine the underlying mechanisms, Reynolds-averaged Navier–Stokes ( RANS ) simulations and energy budget analysis were performed. The results indicate that pressure loss is closely associated with viscous dissipation of mean kinetic energy ( MKE ), while production of TKE contributes less under the present conditions. Furthermore, a strong correlation was observed between pressure loss and in-plane MKE , suggesting that in-plane MKE can serve as a surrogate metric for estimating pressure loss, particularly given the difficulty of directly measuring viscous dissipation in clinical settings. Although based on a simplified geometry and steady flow conditions, the present study provides a quantitative and mechanistic framework for understanding jet-orientation-induced pressure loss, offering a reference for interpreting flow variations in both physiological and engineering systems.