Abstract
A discrete vortex method is implemented with a hybrid control technique of vortex shedding to solve the problem of the two-dimensional flow past a slightly rough circular cylinder in the vicinity of a moving wall. In the present approach, the passive control technique is inspired on the fundamental principle of surface roughness, promoting modifications on the cylinder geometry to affect the vortex shedding formation. A relative roughness size of ε*/d* = 0.001 (ε* is the average roughness and d* is the outer cylinder diameter) is chosen for the test cases. On the other hand, the active control technique uses a wall plane, which runs at the same speed as the free stream velocity to contribute with external energy affecting the fluid flow. The gap-to-diameter varies in the range from h*/d* = 0.05 to 0.80 (h* is the gap between the moving wall and the cylinder bottom). A detailed account of the time history of pressure distributions, simultaneously investigated with the time evolution of forces, Strouhal number behavior, and boundary layer separation are reported at upper-subcritical Reynolds number flows of Re = 1.0 × 105. The saturation state of the numerical simulations is demonstrated through the analysis of the Strouhal number behavior obtained from temporal history of the aerodynamic loads. The present work provides an improvement in the prediction of Strouhal number than other studies no using roughness model. The aerodynamic characteristics of the cylinder, as well as the control of intermittence and complete interruption of von Kármán-type vortex shedding have been better clarified.
Highlights
In the literature, “bluff body” is defined as being a structure that when immerse in a fluid flow will present significant proportion of its surface generating separated flow
The present paper aims to contribute with more discussions concerning the surface roughness effect on bluff body aerodynamics
The chosen dimensionless time step was found suitable to compute aerodynamic loads with accuracy reducing the final time of the simulations
Summary
“bluff body” is defined as being a structure that when immerse in a fluid flow will present significant proportion of its surface generating separated flow. Alcântara Pereira et al [10] proposed a hybrid control technique of vortex shedding, combining passive and active controls, to study the flow past the rough circular cylinder in the vicinity of a moving wall at upper-subcritical Reynolds number of Re = 1.0 × 105 They successfully associated the methodologies developed by Bimbato et al [11,21,22] focusing on the effect of higher relative roughness sizes, namely, ε*/d* = 0.0045 and 0.007, on flow dynamics of the cylinder at small-gap regime, which was identified in past investigation by Bimbato et al [22] at h*/d* < 0.20.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
