2023/11/30 by Valerio Lupi, Lupi, Valerio, J.S. Kern +3
Engineering · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Vibration Analysis #Heat Transfer and Boiling Studies #Nuclear Engineering Thermal-Hydraulics
paper · pdf · doi:10.48550/arxiv.2312.00146
openalex publication_date 2023/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
This study analyses the main characteristics of the fully developed laminar pulsatile flow in a toroidal pipe as the governing parameters vary. A novel computational technique is developed to obtain time-periodic solutions of the Navier\unicodex2013Stokes equations. They are computed as fixed points of the system in the frequency domain via a Newton\unicodex2013Raphson method. Advantages and drawbacks of the adopted methodology with respect to a time-stepping technique are discussed. The unsteady component of the driving pressure gradient is found to change linearly with the pulsation amplitude, with a proportionality coefficient dependent on the pulsation frequency. Although the time-averaged streamwise wall shear stress is very close to the value in the steady case, significant fluctuations are observed within the period. Flow reversal occurs during certain time intervals in the period for high pulsation amplitudes. The analysis of the spatial structure of the unsteady component of the velocity field shows that three different flow regimes can be identified, depending on the pulsation frequency, termed quasi-steady, intermediate and plug-flow regimes.