Drop Formation in Non-Newtonian Jets at Low Reynolds Numbers

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
V. Dravid ◽  
P. B. Loke ◽  
C. M. Corvalan ◽  
P. E. Sojka
Keyword(s):  
High Speed ◽  
Reynolds Numbers ◽  
Shear Thinning ◽  
Liquid Jets ◽  
Initial Increase ◽  
Low Reynolds Numbers ◽  
Subsequent Decrease ◽  
Satellite Drops ◽  
Element Approach ◽  
Secondary Objective

The objective of this study was to develop an experimentally verified computational model that accurately predicts evolution of shear-thinning liquid jets. A secondary objective was to investigate the formation of satellite drops and to determine conditions under which their diameter can be controlled. The model employs the Galerkin finite/element approach to solve the complete two-dimensional set of axisymmetric governing equations and the corresponding kinematic and dynamic boundary conditions at the free surface. The effect of shear-thinning behavior on breakup was studied in detail for the case of an infinitely long non-Newtonian jet. It was found that shear-thinning behavior may be useful in controlling satellite drop sizes. (We observe that increasing the shear-thinning behavior at Re∼5 leads to an initial increase in the satellite drop size, followed by a subsequent decrease.) Comparison of model predictions with experimental data is presented for the case of a shear-thinning non-Newtonian jet. The experimental liquid was pumped through a capillary and drop shapes obtained using a high speed camera. The experimentally obtained shapes were compared to those predicted by the model and found to be in good agreement.

Drop Formation in Non-Newtonian Jets at Low Reynolds Number

2006 ◽  
Author(s):  
Vineet Dravid ◽  
Ping Bu Loke ◽  
Carlos M. Corvalan ◽  
Paul E. Sojka
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Computational Models ◽  
Shear Thinning ◽  
Liquid Jets ◽  
Initial Increase ◽  
Element Analysis ◽  
Subsequent Decrease ◽  
Satellite Drops ◽  
Moderate Reynolds Number

The major objective of this work is to develop accurate computational models to predict evolution of shear thinning liquid jets. A secondary objective is to investigate the formation of satellite drops, and to determine the conditions under which their diameter can be controlled. The theoretical approach of Galerkin-finite element analysis is used solve the complete two-dimensional set of axisymmetric governing equations and the kinematic and dynamic boundary conditions at the free surface. The effect of shear thinning behavior on break-up is studied in detail, in the case of an infinitely long non-Newtonian jet. It is found that the shear thinning behavior may be useful in controlling satellite drop sizes. (We observe that increasing the shear thinning behavior at moderate Reynolds number (Re = 5) leads to an initial increase in the satellite drop size, followed by a subsequent decrease.) Experimental validation for the theory is then presented for the case of a shear thinning non-Newtonian jet. The experimental fluid is pumped through a capillary and drop shapes are obtained using a high speed camera. The experimentally obtained shapes are compared to those predicted by theory with results found to be in good agreement.

scholarly journals Soft Matter Emerging Investigators Issue 2021 - "Propulsion of an elastic filament in a shear-thinning fluid at low Reynolds numbers"

Soft Matter ◽  
2021 ◽  
Author(s):  
Ke Qin ◽  
Zhiwei Peng ◽  
Ye Chen ◽  
Herve Nganguia ◽  
Lailai Zhu ◽  
...  
Keyword(s):  
Soft Matter ◽  
Reynolds Numbers ◽  
Shear Thinning ◽  
Low Reynolds Numbers ◽  
Elastic Filament ◽  
Low Reynolds ◽  
Micro Organisms ◽  
Surrounding Fluid ◽  
Shear Thinning Fluid ◽  
Flexible Appendages

Some micro-organisms and artificial micro-swimmers propel at low Reynolds numbers (Re) via the interaction of their flexible appendages with the surrounding fluid. While their locomotion have been extensively studied with...

Separation and Transition Control on an Aft-Loaded Ultra-High-Lift LP Turbine Blade at Low Reynolds Numbers: High-Speed Validation

2006 ◽  
Vol 129 (2) ◽  
pp. 340-347 ◽  
Author(s):  
Maria Vera ◽  
Xue Feng Zhang ◽  
Howard Hodson ◽  
Neil Harvey
Keyword(s):  
Surface Roughness ◽  
Mach Number ◽  
Surface Finish ◽  
High Speed ◽  
Reynolds Numbers ◽  
High Lift ◽  
Low Reynolds Numbers ◽  
Low Speed ◽  
Transition Mechanism ◽  
Low Reynolds

This paper presents the second part of an investigation of the combined effects of unsteadiness and surface roughness on an aft-loaded ultra-high-lift low-pressure turbine (LPT) profile at low Reynolds numbers. The investigation has been performed using low- and high-speed cascade facilities. The low- and high-speed profiles have been designed to have the same normalized isentropic Mach number distribution. The low-speed results have been presented in the first part (Zhang, Vera, Hodson, and Harvey, 2006, ASME J. Turbomach., 128, pp. 517–527). The current paper examines the effect of different surface finishes on an aft-loaded ultra-high-lift LPT profile at Mach and Reynolds numbers representative of LPT engine conditions. The surface roughness values are presented along with the profile losses under steady and unsteady inflow conditions. The results show that the use of a rough surface finish can be used to reduce the profile loss. In addition, the results show that the same quantitative values of losses are obtained at high- and low-speed flow conditions. The latter proves the validity of the low-speed approach for ultra-high-lift profiles for the case of an exit Mach number of the order of 0.64. Hot-wire measurements were carried out to explain the effect of the surface finish on the wake-induced transition mechanism.

Drone Scale Coaxial Rotor Aerodynamic Interactions Investigation

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Dhwanil Shukla ◽  
Narayan Komerath
Keyword(s):  
High Speed ◽  
Vortex Sheet ◽  
Reynolds Numbers ◽  
Thrust Coefficient ◽  
Low Reynolds Numbers ◽  
Rotor Aerodynamics ◽  
Induced Drag ◽  
Coaxial Rotor ◽  
Simplifying Assumptions ◽  
Uninhabited Aerial Vehicles

Coaxial rotor uninhabited aerial vehicles (UAVs) are compact compared to single rotor UAVs of comparable capacity. At the low Reynolds numbers (Re) where they operate, the simplifying assumptions from high Re rotor aerodynamics are not valid. The low Re coaxial rotor flowfield is studied including aerodynamic interactions and their effect on performance. The evolution of the wake is captured using high-speed stereo particle image velocimetry (SPIV). Improvement of upper rotor performance due to viscous swirl recovery from the lower rotor is discovered and then verified by analyzing PIV data. Interesting vortex–vortex sheet interactions are observed under the coaxial rotor affecting wake structure spatially and temporally. A qualitative model explaining the observed wake interaction phenomena is presented. Comparison with the performance of high Re rotors shows higher profile and induced drag at low Re for the same thrust coefficient.

scholarly journals Studying the unsteady characteristics of a laminar transonic buffet depending on the angle of attack

2021 ◽  
Vol 2057 (1) ◽  
pp. 012009
Author(s):  
P A Polivanov ◽  
A A Sidorenko
Keyword(s):  
Shock Wave ◽  
Unsteady Flow ◽  
High Speed ◽  
Angle Of Attack ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Unsteady Characteristics ◽  
Basic Experiments ◽  
Transonic Buffet ◽  
Amplitude Characteristics

Abstract Laminar transonic buffet on the airfoil for low Reynolds numbers of 0.5-0.7⋅106 was experimentally studied. Basic experiments were performed using high-speed schlieren imaging. The unsteady flow structure was investigated using various methods. It was found that shock wave oscillations can be significantly different from the turbulent case. The frequency and amplitude characteristics of oscillations from the angle of attack were found.

Micro Vortex Flow Induced by Small Life

2007 ◽  
Author(s):  
O. Mochizuki
Keyword(s):  
High Speed ◽  
Ccd Camera ◽  
Reynolds Numbers ◽  
Artemia Salina ◽  
The Body ◽  
Power Stroke ◽  
Low Reynolds Numbers ◽  
Flapping Motion ◽  
Vortex Pairs ◽  
Low Reynolds

We investigated the relations between swimming motions and flow fields around plankton that is a larva of brine-shrimp (Artemia salina) and jellyfish (Aurelia aurita). These move in low Reynolds numbers by flapping motion in common. We recorded motions and flow by using a high speed CCD camera, and analyzed by a motion analysis and PIV method. We observed vortex pairs in each case as a result of power stroke and recovery stroke of pitching motion. Force acting on the body was estimated by measured acceleration of the body. Mechanism of generation of thrust force related to vortex pairs by flapping motion in low Reynolds number environment was discussed in this paper.

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