arXiv subjects

Xavier Amandolese

Publications and source records attributed to Xavier Amandolese.

4 recordsLinked to original sources

arXiv2023

Field tests on a full-scale steel chimney subjected to vortex-induced vibrations

Industrial chimneys, launch vehicles and stacks are examples of large diameter circular cross section structures which can be prone to cross-wind vortex-induced vibrations. VIV has been extensively studied for both fundamental and applied issues, but few documented studies concern high Reynolds number regime (over 500 000) in atmospheric turbulent wind. This paper introduces a field test on a slender light and low damped chimney designed to experience supercritical VIV at moderate wind velocity. The chimney was recently erected in a wind monitored field, near the Atlantic coast of France. The purpose of this paper is to present the first vibration results obtained during a sequential 13 days period in September 2020. A statistical analysis has been performed on the amplitude and dominant frequency responses and results are reported in term of probability distribution as a function of wind speed and direction. VIV events of low (under 15 % of diameter) to moderate amplitude (over 30 % of diameter) have been highlighted in a range of wind velocity 25 % lower than expected, along with significant influence of the wind direction. Low turbulent easterly wind giving vortex induced vibrations with the highest amplitude.

physics.flu-dyn↗

arXiv2023

In wind tunnel the reproduction of vortex shedding behind circular cylinders at high Reynolds number regimes is incomplete

Wind tunnel tests of 2D rough cylinders are presented. The goal is to simulate the alternate vortex shedding in flow regimes encountered in wind engineering applications, where the full scale Reynolds number is larger than the one that can be reproduced in wind tunnel with small scaled models. Measurements are mainly the synchronized unsteady wall pressures on the cylinder which are post processed using bi-orthogonal decompositions. By comparing the small scale results with those from a previous large scale experiment, we show that the technique of rough cylinder is incomplete and can approach roughly global parameters only.

physics.flu-dyn↗

arXiv2023

Twin Strouhal numbers in pressure loading of circular cylinder at high Reynolds numbers

We present a wind tunnel experiment on a large smooth circular cylinder mounted between walls. The Reynolds number range of interest is [800 000 : 2 170 000]. This low supercritical regime is often encountered in wind engineering applications, especially the excitation of flexible circular structures by vortex shedding. Main measurements are the unsteady wall pressure distributions around the cylinder by means of synchronized pressure taps with high resolution in time and space. By using the bi-orthogonal decomposition of this set of signals, twin Strouhal numbers are detected which correspond to the second and the fourth terms of the decomposition. These terms are found to produce the unsteady lift on the cylinder with a main contribution of the second one for which the associated Strouhal number is close to the one usually found at subcritical Reynolds numbers.

physics.flu-dyn↗

arXiv2020

Amplitude hysteresis and the synchronization region: Prediction of vortex-induced vibration using a freely forced van der Pol oscillator

Vortex-induced vibration is a nonlinear phenomenon that can damage buildings or produce energy. Here, the range of synchronization between fluid and structure is an important parameter. Using a coupled van der Pol and linear oscillator system, we derived an analytic, closed-form expression for the synchronization range as a function of fluid shedding frequency, or lock-in as it's also called. Our new definition is an improvement to an earlier synchronization definition as it includes the effect of dissipation; without it hysteresis is missing. The fluid speed range with hysteresis is found to be non-monotonic with forcing strength while the region of absolute synchronization increases monotonically. Our proposed synchronization definition can be a useful tool when designing structural dampers or energy harvesters but is a general solution for all systems that can be modeled with similarly coupled equations.

nlin.PS↗