Numerical investigation of different aspect ratios for flow past three inline rectangular cylinders

2018 ◽  
Vol 40 (9) ◽  
Author(s):  
Shams Ul Islam ◽  
Raheela Manzoor ◽  
Zhou Chao Ying ◽  
Zia Ul Islam
Keyword(s):  
Numerical Investigation ◽  
Aspect Ratios ◽  
Flow Past ◽  
Rectangular Cylinders

Linear stability of the steady flow past rectangular cylinders

2021 ◽  
Vol 929 ◽  
Author(s):  
A. Chiarini ◽  
M. Quadrio ◽  
F. Auteri
Keyword(s):  
Aspect Ratio ◽  
Critical Reynolds Number ◽  
Leading Edge ◽  
Curvature Radius ◽  
Trailing Edge ◽  
Aspect Ratios ◽  
A Value ◽  
Flow Past ◽  
Rectangular Cylinders ◽  
Primary Instability

The primary instability of the flow past rectangular cylinders is studied to comprehensively describe the influence of the aspect ratio $AR$ and of rounding the leading- and/or trailing-edge corners. Aspect ratios ranging between $0.25$ and $30$ are considered. We show that the critical Reynolds number ( $\textit {Re}_c$ ) corresponding to the primary instability increases with the aspect ratio, starting from $\textit {Re}_c \approx 34.8$ for $AR=0.25$ to a value of $\textit {Re}_c \approx 140$ for $AR = 30$ . The unstable mode and its dependence on the aspect ratio are described. We find that positioning a small circular cylinder in the flow modifies the instability in a way strongly depending on the aspect ratio. The rounded corners affect the primary instability in a way that depends on both the aspect ratio and the curvature radius. For small $AR$ , rounding the leading-edge corners has always a stabilising effect, whereas rounding the trailing-edge corners is destabilising, although for large curvature radii only. For intermediate $AR$ , instead, rounding the leading-edge corners has a stabilising effect limited to small curvature radii only, while for $AR \geqslant 5$ it has always a destabilising effect. In contrast, for $AR \geqslant 2$ rounding the trailing-edge corners consistently increases $\textit {Re}_c$ . Interestingly, when all the corners are rounded, the flow becomes more stable, at all aspect ratios. An explanation for the stabilising and destabilising effect of the rounded corners is provided.

Effect of aspect ratios on flow past a row of rectangular cylinders for various gap spacings

2018 ◽  
Vol 72 ◽  
pp. 374-390 ◽  
Author(s):  
Hamid Rahman ◽  
Shams Ul Islam ◽  
Waqas Sarwar Abbasi ◽  
Safyan Mukhtar ◽  
Chao Ying Zhou
Keyword(s):  
Aspect Ratios ◽  
Flow Past ◽  
Gap Spacings ◽  
Rectangular Cylinders

Hybrid Analytical-Numerical Analysis of SAE 4150 Alloy Steel Rods Cooling

2014 ◽  
Vol 1082 ◽  
pp. 187-190 ◽  
Author(s):  
Marcelo Ferreira Pelegrini ◽  
Thiago Antonini Alves ◽  
Felipe Baptista Nishida ◽  
Ricardo A. Verdú Ramos ◽  
Cassio R. Macedo Maia
Keyword(s):  
Diffusion Equation ◽  
Alloy Steel ◽  
Integral Transform ◽  
Numerical Study ◽  
Physical Parameters ◽  
Analytical Treatment ◽  
Aspect Ratios ◽  
Rectangular Cylinders ◽  
Thermo Physical Properties ◽  
Integral Transform Technique

In this work, a hybrid analytical-numerical study was performed in cooling of rectangular rods made from SAE 4150 alloy steel (0.50% carbon, 0.85% chrome, 0.23% molybdenum, and 0.30% silicon). The analysis can be represented by the solution of transient diffusive problems in rectangular cylinders with variable thermo-physical properties in its domain under the boundary conditions of first kind (Dirichlet condition) and uniform initial condition. The diffusion equation was linearized through the Kirchhoff Transformation on the temperature potential to make the analytical treatment easier. The Generalized Integral Transform Technique (GITT) was applied on the diffusion equation in the domain in order to determine the temperature distribution. The physical parameters of interest were determined for several aspect ratios and compared with the results obtained through numerical simulations using the commercial software ANSYS/FluentTM15.

Sign in / Sign up

Export Citation Format

Share Document