Numerical investigations of the flow around four non-aligned circular cylinders
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ORIGINAL PAPER
Numerical investigations of the flow around four non‑aligned circular cylinders Daniela Miwa Uemura Kawaguti1 · Guilherme Rosa Franzini1 Received: 6 December 2019 / Accepted: 13 June 2020 © Sociedade Brasileira de Engenharia Naval 2020
Abstract This works aims at numerically investigating the flow around a group of four non-aligned cylinders, for two different angles of incidence, β = 0° and 180° at Reynolds number (Re) equal to 200. The influence of the proximity between the cylinders is investigated by means of the numerical analysis based on Computational Fluid Dynamics (CFD), using a finite volume method with two-dimensional unstructured meshes. The distance between cylinders and the angle of incidence has a great influence on the flow behavior, which is reflected on the analysis of the force coefficients and the Strouhal number. At β = 0°, it is observed the presence of two regimes in the time series of the lift coefficient, which lifespan of the first regime is reduced with increase of the spacing ratio. Also, different drag coefficients were seen at spacing ratio equals to 3.5 D for the rear cylinders. Regarding to the results with β = 180°, they showed multiple peaks on the lift coefficient amplitude spectrum for the rear cylinders. This work contributes to enhance the understanding of the flow around multiple cylinders, mainly regarding non-traditional configurations such as tandem and side-by-side arrangements. Keywords Interference phenomenon · Computational fluid dynamics · Flow around multiple cylinders · Numerical simulation
1 Introduction Despite the fact that the flow around an isolated circular cylinder is a well-established topic, the addition of other bodies to the problem leads to effects of flow interference. This phenomenon is consequence of numerous aspects such as the proximity, quantity, and geometry of the considered bodies. The incidence angle and the Reynolds number also play an important role on the flow characteristics. The flow around multiple cylinders is a complex problem with several engineering applications such as in risers, columns of offshore platforms, chimneys, and buildings. Although the main attention is on the cylinders themselves, the entire system (the array of cylinders) is affected by the flow. Example of such behavior can be found at Ghodsi and Khanjani [1], where the authors investigated the use of an artificial intelligence method to predict scour depth at complex bridge piers. * Daniela Miwa Uemura Kawaguti [email protected] 1
Offshore Mechanics Laboratory (LMO), Escola Politécnica, University of São Paulo, São Paulo, Brazil
The complexity of the engineering problems made experimental investigations non-trivial tasks. Among the limitations, it can be pointed out the difficulty in obtaining specific Reynolds numbers and the impossibility of assessing the desirable number of parameters such as the velocity of the fluid in specific points. This context and the development of numerical tools facilitated the increase of computational st
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