scholarly journals Low Reynolds Number Pulsatile Flow of a Viscoelastic Fluid Through a Channel: Effects of Fluid Rheology and Pulsation Parameters

2021 ◽  
Author(s):  
Subhasisa Rath ◽  
Bimalendu Mahapatra
Keyword(s):  
Reynolds Number ◽  
Viscoelastic Fluid ◽  
Pulsatile Flow ◽  
Low Reynolds Number ◽  
Flow Characteristics ◽  
Deborah Number ◽  
Pulsation Frequency ◽  
Process Industries ◽  
Fluid Elasticity ◽  
Low Reynolds

Abstract As the first endeavour, we have analyzed the pulsatile flow of Oldroyd-B viscoelastic fluid where the combined effects of fluid elasticity and pulsation parameters on the flow characteristics are numerically studied at a low Reynolds number. Computations are performed using a finite-volume based open-source solver OpenFOAM\textsuperscript{\textregistered} by appending the log-conformation tensor approach to stabilize the numerical solution at high Deborah number. Significant flow velocity enhancement is achieved by increasing the viscoelastic behaviour of the fluid. High-velocity gradient zones and high polymeric stress regions are observed near the channel wall. The magnitude of axial velocity attenuates with increasing pulsation amplitude or pulsation frequency, and the extent of this attenuation is highly dependent on the Deborah number or the retardation ratio. This work finds application in the transport of polymeric solutions, extrusion, and injection moulding of polymer melts in several process industries.

Comparative Investigation of Laminar Separation Bubble on a Wing at Low Reynolds Number

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
M.P. Uthra ◽  
A. Daniel Antony
Keyword(s):  
Reynolds Number ◽  
Separation Bubble ◽  
Low Reynolds Number ◽  
Flow Characteristics ◽  
Suction Side ◽  
Aerodynamic Performance ◽  
Laminar Separation Bubble ◽  
Laminar Separation ◽  
Low Reynolds ◽  
Air Vehicles

Most admirable and least known features of low Reynolds number flyers are their aerodynamics. Due to the advancements in low Reynolds number applications such as Micro Air vehicles (MAV), Unmanned Air Vehicles (UAV) and wind turbines, researchers’ concentrates on Low Reynolds number aerodynamics and its effect on aerodynamic performance. The Laminar Separation Bubble (LSB) plays a deteriorating role in affecting the aerodynamic performance of the wings. The parametric study has been performed to analyse the flow around cambered, uncambered wings with different chord and Reynolds number in order to understand the better flow characteristics, LSB and three dimensional flow structures. The computational results are compared with experimental results to show the exact location of LSB. The presence of LSB in all cases is evident and it also affects the aerodynamic characteristics of the wing. There is a strong formation of vortex in the suction side of the wing which impacts the LSB and transition. The vortex structures impact on the LSB is more and it also increases the strength of the LSB throughout the span wise direction.

Flow Characteristics of a Low Reynolds Number Jet in Crossflow with an Obstacle Block

2016 ◽  
Vol 9 (1) ◽  
pp. 37-46 ◽  
Author(s):  
Jianlong Chang ◽  
Xudong Shao ◽  
Xiao Hu ◽  
Shuangbiao Zhang
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Velocity Ratio ◽  
Flow Characteristics ◽  
Vortex Pair ◽  
Lower Velocity ◽  
Eddy Simulation ◽  
Jet In Crossflow ◽  
Crossflow Velocity ◽  
Low Reynolds

The jet in crossflow at very low Reynolds number (Re=100) with and without block is performed by means of large eddy simulation for the jet-to-crossflow velocity ratios (r) ranging from 1 to 3, and the corresponding flow characteristics are compared. The results show that the time-averaged particle trajectories of the jet are slightly changed if a block is presented, and the mixed vortices are weakened. The existence of the block also can accelerate the formation of stable counter-rotating vortex pair. At lower velocity ratio (r=1), the block has little effect on the jet in crossflow with a symmetrically positive and negative kidney shaped vortices. As the velocity ratio increases, the effect of block not only can generate an asymmetry of positive and negative kidney shaped vortices, but also it can reinforce the interaction between the positive and negative vortices in the jet in crossflow. The effect of block on the temperature field is also analyzed in detail.

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