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LES of flow around two staggered circular cylinders at a high subcritical Reynolds number of 1.4×105
Abstract This paper presents a numerical study of the flow around two static staggered circular cylinders at a high subcritical Reynolds number of Re = 1.4 × 105. The center-to-center pitch ratio (P/D) varied from 1.5 to 4, and the incidence angle (β) increased from 0° to 90°. Three critical aerodynamic phenomena at the downstream cylinder—negative drag force, inner lift force, and outer lift force—are successfully simulated. New explanations for the phenomena are proposed. The negative drag force appears at approximately P/D = 1.5–2 and β = 0°–10°, which is ascribed to a recirculation pair with opposite directions and a high-speed gap flow between the cylinders in the tandem and staggered configurations, respectively. The inner lift force happens at about P/D = 1.5–3 and β = 10°, which is due to the combined effects of a stagnation point shift, high-speed gap flow, and rising of the gap-side unsteady separation bubble at the downstream cylinder. The outer lift force occurs at about β = 20° and P/D = 3–4, which is attributed to a gap-side separation point shift from windward to leeward and interactions between the vortices shed from the upstream cylinder and the shear layer of the downstream cylinder.
Highlights The flow around two staggered circular cylinders is simulated at a high subcritical Reynolds number of 1.4 × 105. The relationship between the aerodynamic characteristics and the flow features is established. New explanations are proposed for the negative drag force, the inner lift force and the outer lift force of downstream cylinder. The unsteady separation bubble contributes a lot to the inner lift force of the downstream cylinder. The lower separation point of the downstream cylinder shifts downwards, which contributes to the outer lift force.
LES of flow around two staggered circular cylinders at a high subcritical Reynolds number of 1.4×105
Abstract This paper presents a numerical study of the flow around two static staggered circular cylinders at a high subcritical Reynolds number of Re = 1.4 × 105. The center-to-center pitch ratio (P/D) varied from 1.5 to 4, and the incidence angle (β) increased from 0° to 90°. Three critical aerodynamic phenomena at the downstream cylinder—negative drag force, inner lift force, and outer lift force—are successfully simulated. New explanations for the phenomena are proposed. The negative drag force appears at approximately P/D = 1.5–2 and β = 0°–10°, which is ascribed to a recirculation pair with opposite directions and a high-speed gap flow between the cylinders in the tandem and staggered configurations, respectively. The inner lift force happens at about P/D = 1.5–3 and β = 10°, which is due to the combined effects of a stagnation point shift, high-speed gap flow, and rising of the gap-side unsteady separation bubble at the downstream cylinder. The outer lift force occurs at about β = 20° and P/D = 3–4, which is attributed to a gap-side separation point shift from windward to leeward and interactions between the vortices shed from the upstream cylinder and the shear layer of the downstream cylinder.
Highlights The flow around two staggered circular cylinders is simulated at a high subcritical Reynolds number of 1.4 × 105. The relationship between the aerodynamic characteristics and the flow features is established. New explanations are proposed for the negative drag force, the inner lift force and the outer lift force of downstream cylinder. The unsteady separation bubble contributes a lot to the inner lift force of the downstream cylinder. The lower separation point of the downstream cylinder shifts downwards, which contributes to the outer lift force.
LES of flow around two staggered circular cylinders at a high subcritical Reynolds number of 1.4×105
Wu, Gefei (author) / Du, Xiaoqing (author) / Wang, Yuliang (author)
2019-11-10
Article (Journal)
Electronic Resource
English
Flow around a circular cylinder in linear shear flows at subcritical Reynolds number
| Online Contents | 2008
Flow around a circular cylinder in linear shear flows at subcritical Reynolds number
| Online Contents | 2008