Investigation of drag properties for flow through and around square arrays of cylinders at low Reynolds numbers

2019 ◽  
Vol 199 ◽  
pp. 285-301 ◽  
Author(s):  
Tingting Tang ◽  
Peng Yu ◽  
Xiaowen Shan ◽  
Huisu Chen ◽  
Jian Su
Keyword(s):  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Flow Through ◽  
Low Reynolds

scholarly journals Flow through pipe orifices at low Reynolds numbers

1930 ◽  
Vol 126 (801) ◽  
pp. 231-245 ◽  
Keyword(s):  
Turbulent Flow ◽  
Discharge Coefficient ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Orifice Diameter ◽  
Vortex System ◽  
Low Reynolds Numbers ◽  
Commercial Practice ◽  
Flow Through ◽  
Low Reynolds

Most of the experimental work in connection with the flow of fluids through diaphragm orifices in pipe lines has been directed to the establishment of the orifice as a flow meter, and has been carried out at the velocities of flow commonly encountered in commercial practice. As a result of such research the coefficients relating the volumetric discharge of incompressible fluids to the differential head across an orifice are well known over a large range of high Reynolds numbers. For a particular diameter ratio ( i. e., orifice diameter ÷ diameter of pipe line) the discharge coefficient is nearly constant under conditions of turbulent flow. Over the range from steady to turbulent flow, however, very appreciable variations occur in the value of the discharge coefficient, suggest­ing that the accompanying variations in the nature of the flow through and beyond the orifice will be no less marked. As regards the turbulent flow pattern, an investigation, in which the author collaborated, of the airflow downstream of a flat plate suggests that an orifice in a pipe will in general give rise to a vortex system, probably having some points of resemblance to the well-known Kármán street which is a feature of the two-dimensional flow past a bluff obstacle, but doubtless exhibiting interesting differences arising from the symmetrical and three-dimensional character of the flow through an orifice. At sufficiently low Reynolds numbers, on the other hand, perfect flow free from periodic vorticity will occur. The stages connecting these two extreme conditions present many points of interest not only as regards the nature of the vortex system downstream of the orifice and the conditions of flow covering its inception, but also as regards the accom­panying pressure-velocity relation during the transition.

scholarly journals Analysis of vortices in viscoelastic fluid flow through confined geometries at low Reynolds numbers

AIP Advances ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 085213
Author(s):  
Ali Zargartalebi ◽  
Mohammad Zargartalebi ◽  
Anne M. Benneker
Keyword(s):  
Fluid Flow ◽  
Viscoelastic Fluid ◽  
Reynolds Numbers ◽  
Confined Geometries ◽  
Low Reynolds Numbers ◽  
Flow Through ◽  
Low Reynolds

Global Linear Instability of Flow Through a Converging–Diverging Channel

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Mamta R. Jotkar ◽  
Gayathri Swaminathan ◽  
Kirti Chandra Sahu ◽  
Rama Govindarajan
Keyword(s):  
Reynolds Numbers ◽  
Linear Instability ◽  
Stability Study ◽  
Base Flow ◽  
Low Reynolds Numbers ◽  
Critical Reynolds Numbers ◽  
Diverging Channel ◽  
Order Of Magnitude ◽  
Flow Through ◽  
Low Reynolds

The global linear stability, where we assume no homogeneity in either of the spatial directions, of a two-dimensional laminar base flow through a spatially periodic converging–diverging channel is studied at low Reynolds numbers. A large wall-waviness amplitude is used to achieve instability at critical Reynolds numbers below ten. This is in contrast to earlier studies, which were at lower wall-waviness amplitude and had critical Reynolds numbers an order of magnitude higher. Moreover, our leading mode is a symmetry-breaking standing mode, unlike the traveling modes which are standard at higher Reynolds numbers. Eigenvalues in the spectrum lie on distinct branches, showing varied structure spanning the geometry. Our global stability study suggests that such modes can be tailored to give enhanced mixing in microchannels at low Reynolds numbers.

Investigation on the effect of leading edge tubercles of sweptback wing at low reynolds number

2020 ◽  
Vol 21 (6) ◽  
pp. 621
Author(s):  
Veerapathiran Thangaraj Gopinathan ◽  
John Bruce Ralphin Rose ◽  
Mohanram Surya
Keyword(s):  
Leading Edge ◽  
Reynolds Numbers ◽  
Sweep Angle ◽  
Laminar Separation ◽  
Low Reynolds Numbers ◽  
Flow Energy ◽  
Airplane Wing ◽  
Low Reynolds ◽  
Naca 0015 ◽  
Wing Performance

Aerodynamic efficiency of an airplane wing can be improved either by increasing its lift generation tendency or by reducing the drag. Recently, Bio-inspired designs have been received greater attention for the geometric modifications of airplane wings. One of the bio-inspired designs contains sinusoidal Humpback Whale (HW) tubercles, i.e., protuberances exist at the wing leading edge (LE). The tubercles have excellent flow control characteristics at low Reynolds numbers. The present work describes about the effect of tubercles on swept back wing performance at various Angle of Attack (AoA). NACA 0015 and NACA 4415 airfoils are used for swept back wing design with sweep angle about 30°. The modified wings (HUMP 0015 A, HUMP 0015 B, HUMP 4415 A, HUMP 4415 B) are designed with two amplitude to wavelength ratios (η) of 0.1 & 0.24 for the performance analysis. It is a novel effort to analyze the tubercle vortices along the span that induce additional flow energy especially, behind the tubercles peak and trough region. Subsequently, Co-efficient of Lift (CL), Co-efficient of Drag (CD) and boundary layer pressure gradients also predicted for modified and baseline (smooth LE) models in the pre & post-stall regimes. It was observed that the tubercles increase the performance of swept back wings by the enhanced CL/CD ratio in the pre-stall AoA region. Interestingly, the flow separation region behind the centerline of tubercles and formation of Laminar Separation Bubbles (LSB) were asymmetric because of the sweep.

Low Reynolds number flow around and heat transfer from a heated circular cylinder

2010 ◽  
Vol 1 (1-2) ◽  
pp. 15-20 ◽  
Author(s):  
B. Bolló
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Reynolds Number Flow ◽  
Two Dimensional Flow ◽  
Number Flow ◽  
Low Reynolds ◽  
Increasing Temperature

Abstract The two-dimensional flow around a stationary heated circular cylinder at low Reynolds numbers of 50 < Re < 210 is investigated numerically using the FLUENT commercial software package. The dimensionless vortex shedding frequency (St) reduces with increasing temperature at a given Reynolds number. The effective temperature concept was used and St-Re data were successfully transformed to the St-Reeff curve. Comparisons include root-mean-square values of the lift coefficient and Nusselt number. The results agree well with available data in the literature.

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