Characteristics of flow over two circular cylinders in a side-by-side arrangement at low Reynolds numbers

Abstract

Two-dimensional flow over two circular cylinders in a side-by-side arrangement at low Reynolds numbers has been numerically investigated in this study. For the study, numerical simulations are performed, using the immersed boundary method, in the ranges of 40⩽Re⩽160 and g*<5, where Re and g* are, respectively, the Reynolds number and the spacing between the two cylinder surfaces divided by the cylinder diameter. Results show that a total of six kinds of wake patterns are observed over the ranges: antiphase-synchronized, in-phase-synchronized, flip-flopping, deflected, single bluff-body, and steady wake patterns. It is found that the characteristics of the flow significantly depend both on the Reynolds number and gap spacing, with the latter much stronger than the former. Instantaneous flow fields, time traces, flow statistics and so on are presented to identify the wake pattern and then to understand the underlying mechanism. Moreover, the bifurcation phenomena where either of two wake patterns can occur are found at certain flow conditions.