Release Time:2019-03-12  Hits:

Indexed by: Journal Article

Date of Publication: 2017-05-01

Journal: OCEAN ENGINEERING

Included Journals: EI、SCIE

Volume: 135

Page Number: 28-38

ISSN: 0029-8018

Key Words: Circular cylinder; Cruciform; Drag coefficient; T0 vs. T45 mesh; Wake effect

Abstract: Fluid flow around and drag of two cylindrical cruciform patterns, conventional (T0) and rotated 45 degrees in its own plane (T45), were numerically investigated by solving three-dimensional Reynolds-averaged Navier-Stokes equations within the subcritical flow regime over angles of attack (AOA) from 90 degrees to 0 degrees. Firstly, the drag for a one-cruciform element was assessed, followed by analysis of a four-cruciform assembly ('square mesh') to take into account the wake effect of tandem elements. For the one-cruciform element, T45 experienced a less prominent streamline separation and consequently lower drag between 90 degrees and 45 degrees AOA, while T0 experienced progressively lower drag below 45 degrees AOA owing to re-establishment of smoother streamlines caused by the gradually reduced circulation momentum from the adjacent vortex that rotates in the off-side direction. For the four-cruciform assemblies, T0 and T45 drag was essentially equal above 45 degrees AOA; while below 45 degrees, T45 had greater drag attributed to more prominent spanwise vortex downstream development. Overall, while the largest relative difference between the two orientations was 26.2% and 33.8% for the one- and four-cruciform configurations respectively at 0 degrees AOA, for 30 degrees and above AOA there were limited drag differences (generally below 10%).