Turbulent Pulsatile Pipe Flow with Multiple Modes of Oscillation

This study numerically investigates turbulent pipe flow driven by a pulsating pressure gradient. While studies of laminar and turbulent pulsatile pipe flow with a single mode of oscillating pressure gradient have been carried out extensively, there is scarce literature on pulsating pressure gradients with multiple temporal Fourier modes. In many real-life engineering applications, for example, the arterial systems, multiple Fourier modes are often required for an accurate representation of the driving force. In this paper, direct numerical simulations are carried out to simulate turbulent pulsatile pipe flow driven by a pressure gradient with 2 Fourier oscillating modes whose mean and extrema are similar to those with a single Fourier mode. The presence of the additional mode of oscillation results in no alterations of the global-mean turbulence statistics such that the mean velocity profiles and turbulence intensities, both collapsing onto its single-mode counterpart. It extends the global-mean characteristics of pulsatile flow from single mode to multiple modes of oscillation. The introduction of an extra Fourier mode in this study diminishes the oscillatory part of the flow such that streamwise velocity modulation amplitudes and the turbulence intensity modulations are reduced. Nevertheless, the present result shows the specific response of an additional Fourier model to the pulsatile turbulence flow analyses. Further investigations are needed to provide a general conclusion on the effect of other additional Fourier modes.