Quasi-Periodic Oscillating Flows in a Channel with a Suddenly Expanded Section

Abstract

In this study, two-dimensional numerical simulation was carried out for an oscillatory flow between parallel flat plates having a suddenly expanded section. Governing equations were discretized with the second-order accuracy by a finite volume method on an unequal interval mesh system resolving finer near walls and corners to obtain the characteristics of the oscillatory flow accurately. Amplitude spectrums of a velocity component were obtained to investigate the periodic characteristics of the oscillatory flow. At low Reynolds numbers, the flow is periodic because the spectrum mostly consists of harmonic components, and then at high Reynolds numbers, it transits to a quasi-periodic flow mixed with non-harmonic components. In conjunction with the periodic oscillation of a main flow, separation vortices that are not uniform in size are generated from the corner of a sudden contraction part and pass through a downstream region coming into contact with the wall. The number of the vortices decreases rapidly after they are generated, but the vortices are generated again in the downstream region. In order to specify where aperiodicity is generated, the turbulent kinetic energy is introduced, and it is decomposed into the harmonic and non-harmonic components. The peaks of the non-harmonic component are generated in the region of the expanded section.

Effects of chemical reaction and heat source on MHD oscillatory viscoelastic flow in a channel filled with porous medium

“…The viscoelastic behavior of non-Newtonian fluids subjected to time harmonic oscillation was studied with the analytical solution obtained for the governing equations. Masuda and Tagawa (2019) investigated quasi-periodic oscillating flows in a channel with suddenly expanded section. Two-dimensional numerical simulation was carried out for an oscillatory flow between parallel flat plates having a suddenly expanded section.…”

Weak Local Residuals as Smoothness Indicators in Adaptive Mesh Methods for Shallow Water Flows

“…Castaings and Navon [5] proposed a numerical method for solving reaction-diffusion problems. These fluid dynamics often relate to the theory of conservation laws [6][7][8][9] with finite volume methods [10][11][12][13] as solving techniques. Overall, we can choose a fluid dynamics model in the literature that best suits the problem we want to solve.…”