1,720,987 research outputs found
3D Finite Time Lyapunov Exponents in a left ventricle laboratory model
No full textFinite Time Lyapunov Exponents (FTLEs) are a powerful means to infer characteristic features of the flow that cannot be revealed by other Eulerian criteria. Recently FTLEs are becoming popular also in the medical context, for instance in the analysis of vascular flow measured by means of Magnetic Resonance Imaging. However, many of the FTLE experimental works are based only on two-dimensional velocity fields, moreover those computed on in-vivo data cannot be obtained under controlled and repeatable conditions. Here we present the 3D FTLE evolution inside a Left Ventricle (LV) laboratory model mimicking physiological human conditions. The investigation of FTLE fields highlights distinctive features of the cardiac flow and gives an insight on the physiological development of the Lagrangian Coherent Structures (LCS) that optimize the LV refill
Turbulence investigation in a laboratory model of the ascending aorta
No full textThis study aims to investigate turbulence inside a model of the
human ascending aorta as a function of the main flow control
parameters. For this purpose, we performed a two-dimensional
in vitro investigation of the pulsatile flow inside a laboratory
model of a healthy aorta by varying both the Reynolds and
Womersley numbers. Our findings indicate that the velocity
fluctuations become significant particularly during the
deceleration phase of the flow, reach the maximum near the
systolic peak and then decay during the rest of the diastole
phase. Higher levels of turbulence were recovered for
increasing Stroke Volumes, in particular maxima of Turbulent
Kinetic Energy occurred in the bulk region while higher
values of Reynolds shear stresses were found in
correspondence of the sinus of Valsalva
- …
