Characterizing intraventricular flow patterns via modal decomposition techniques in idealized left ventricle models

Understanding the formation, propagation, and breakdown of vortex rings (VRs) during early filling of the left ventricle (LV) is essential for characterizing cardiac hemodynamics and has been linked to ventricular filling efficiency. In this study, we investigate how ventricular geometry influences vortex ring evolution and apply data-driven modal decomposition techniques to identify the dominant flow mechanisms. Two idealized left ventricle chambers were analyzed using computational fluid dynamics (CFD) under physiological inflow conditions: a semi-ellipsoidal cavity and a more rounded geometry based on experimental measurements. The resulting velocity fields were processed using proper orthogonal decomposition and higher order dynamic mode decomposition to extract the most energetic flow structures and resolve their characteristic frequencies and temporal evolution. The results show that geometric morphology strongly modulates vortex dynamics. In the semi-ellipsoidal chamber, early interaction of the vortex with the walls promotes instabilities and rapid breakdown into smaller structures, leading to a more complex temporal spectrum with enhanced nonlinear modal interactions. In contrast, in the rounded chamber, the vortex propagates farther toward the apex and dissipates more gradually, producing more coherent flow patterns and a clearer frequency content. Both analyses consistently identify a dominant frequency associated with the main cardiac cycle and a secondary frequency linked to the double inflow pulse. These findings demonstrate that ventricular geometry is a key determinant of vortex ring formation and breakdown and highlight the value of combining computational fluid dynamics with modal decomposition as a robust framework for characterizing intraventricular flow, with direct implications for future patient-specific and pathological studies.