The Effect of Design Parameters on the Performance of Flagellar Propeller at Low Reynolds Number

2011 ◽  
Author(s):  
Hyejin Jeon ◽  
Yoon-Cheol Kim ◽  
Eun Goh ◽  
Dongwook Yim ◽  
Songwan Jin ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Rotational Speed ◽  
Low Reynolds Number ◽  
Stereoscopic Particle Image Velocimetry ◽  
Macroscopic Model ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Working Fluid ◽  
Inertia Force ◽  
Low Reynolds

To drive a small object which swims in low Reynolds number situation, we need a new type of propeller which is optimized for low Reynolds number usage since the flow at low Reynolds numbers is dominated by viscous force instead of inertia force. Propeller in a shape of bacterial flagellum can be a strong candidate for propeller of small swimming object. In this paper, we visualized velocity field induced by flagellar shaped propeller using stereoscopic particle image velocimetry. We also have experimentally evaluated the effect of pitch and rotational speeds on the performance of flagellar shaped propeller inspired by flagellum of E.coli using macroscopic model. Silicone oil whose viscosity is 100 times larger than water is used as working fluid to make low Reynolds number situation using macroscopic model. Thrust, torque and velocity were measured as a function of pitch and rotational speed, and efficiency was calculated using measured results. We found that the maximum efficiency of flagellar propeller reaches where the pitch angle is about 40°. However, the effect of rotational speed on the efficiency is relatively smaller than that of pitch. And the flow pattern behind the rotating propeller was altered by pitch of the propeller.

scholarly journals Effect of Rotational Speed on the Stability of Two Rotating Side-by-side Circular Cylinders at Low Reynolds Number

2018 ◽  
Vol 27 (2) ◽  
pp. 125-134
Author(s):  
Huashu Dou ◽  
Shuo Zhang ◽  
Hui Yang ◽  
Toshiaki Setoguchi ◽  
Yoichi Kinoue
Keyword(s):  
Reynolds Number ◽  
Rotational Speed ◽  
Low Reynolds Number ◽  
Circular Cylinders ◽  
Low Reynolds ◽  
The Stability

A Numerical Investigation of Multi-Staged Tesla Valves

2013 ◽  
Author(s):  
Scott M. Thompson ◽  
D. Keith Walters ◽  
Basil J. Paudel ◽  
Tausif Jamal
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Low Reynolds Number ◽  
Three Dimensional ◽  
Check Valve ◽  
Design Parameters ◽  
Optimized Design ◽  
Low Reynolds ◽  
The Individual ◽  
Tesla Valve

The Tesla valve is a passive-type check valve used for flow control/rectification in a variety of micro/mini-channel systems. Previous studies have focused on its optimal design and effectiveness (i.e. diodicity) for the low-Reynolds number regime (Re < 500). Using three-dimensional (3D) CFD, multiple, identically-shaped Tesla valves arranged in-series, i.e.: a Tesla “tree” or multi-staged Tesla valve (MSTV), were investigated. Fully-developed flow at the inlet and complete-laminar conditions throughout the entire valve structure were imposed on all numerical simulations. The number of Tesla valves, valve-to-valve distance and Reynolds number were varied to determine their effect on MSTV diodicity. The individual Tesla valves within each MSTV possessed pre-optimized design parameters as reported from the literature. Results clearly indicate that the MSTV can provide for a significantly higher diodicity than a single Tesla valve and that this MSTV diodicity increases with Reynolds number. Minimizing the distance between adjacent Tesla valves can significantly increase the MSTV diodicity and, for very low Reynolds number (Re < 50), the MSTV diodicity is near-independent of valve-to-valve distance and number of valves used. In general, more Tesla valves are required to maximize the MSTV diodicity as the Reynolds number increases. The current investigation also demonstrates that 3D numerical simulations more accurately predict the diodicity of a single Tesla valve over a wider range of Reynolds numbers.

scholarly journals Experimental insights into flow impingement in cerebral aneurysm by stereoscopic particle image velocimetry: transition from a laminar regime

2013 ◽  
Vol 10 (82) ◽  
pp. 20121031 ◽  
Author(s):  
Takanobu Yagi ◽  
Ayaka Sato ◽  
Manabu Shinke ◽  
Sara Takahashi ◽  
Yasutaka Tobe ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Cerebral Aneurysm ◽  
Particle Image ◽  
Low Reynolds Number ◽  
Stereoscopic Particle Image Velocimetry ◽  
Patient Specific ◽  
Laminar Regime ◽  
Image Velocimetry ◽  
Low Reynolds

This study experimentally investigated the instability of flow impingement in a cerebral aneurysm, which was speculated to promote the degradation of aneurysmal wall. A patient-specific, full-scale and elastic-wall replica of cerebral artery was fabricated from transparent silicone rubber. The geometry of the aneurysm corresponded to that found at 9 days before rupture. The flow in a replica was analysed by quantitative flow visualization (stereoscopic particle image velocimetry) in a three-dimensional, high-resolution and time-resolved manner. The mid-systolic and late-diastolic flows with a Reynolds number of 450 and 230 were compared. The temporal and spatial variations of near-wall velocity at flow impingement delineated its inherent instability at a low Reynolds number. Wall shear stress (WSS) at that site exhibited a combination of temporal fluctuation and spatial divergence. The frequency range of fluctuation was found to exceed significantly that of the heart rate. The high-frequency-fluctuating WSS appeared only during mid-systole and disappeared during late diastole. These results suggested that the flow impingement induced a transition from a laminar regime. This study demonstrated that the hydrodynamic instability of shear layer could not be neglected even at a low Reynolds number. No assumption was found to justify treating the aneurysmal haemodynamics as a fully viscous laminar flow.

Experimental Investigation on Blunt-Edged UTM Delta Wing VFE-2 Configurations at Low Reynolds Number

2018 ◽  
Vol 12 (3) ◽  
pp. 255
Author(s):  
Muhammad Zal Aminullah Daman Huri ◽  
Shabudin Bin Mat ◽  
Mazuriah Said ◽  
Shuhaimi Mansor ◽  
Md. Nizam Dahalan ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Delta Wing ◽  
Low Reynolds Number ◽  
Low Reynolds

HEAT TRANSFER OF IMPINGING JET AT LOW REYNOLDS NUMBER

2018 ◽  
Author(s):  
Vadim V. Lemanov ◽  
Viktor I. Terekhov ◽  
Vladimir V. Terekhov
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Impinging Jet ◽  
Low Reynolds
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