Numerical study on polymer nanofibers with electrically charged jet of viscoelastic fluid in electrospinning process

2017 ◽  
Vol 24 (10) ◽  
pp. 2275-2280 ◽  
Author(s):  
P. Valipour ◽  
H. Zaersabet ◽  
M. Hatami ◽  
Ali Zolfagharian ◽  
S. E. Ghasemi
Keyword(s):  
Viscoelastic Fluid ◽  
Numerical Study ◽  
Electrospinning Process ◽  
Polymer Nanofibers ◽  
Electrically Charged Jet ◽  
Electrically Charged

Effect of finite conductivity on the nonlinear behaviour of an electrically charged viscoelastic liquid jet

2019 ◽  
Vol 874 ◽  
pp. 5-37 ◽  
Author(s):  
Fang Li ◽  
Shi-You Ke ◽  
Xie-Yuan Yin ◽  
Xie-Zhen Yin
Keyword(s):  
Numerical Study ◽  
Electrostatic Force ◽  
Complete Removal ◽  
Bond Number ◽  
Finite Conductivity ◽  
Nonlinear Behaviour ◽  
Secondary Importance ◽  
String Structure ◽  
Electrically Charged Jet ◽  
Electrically Charged

In this paper a one-dimensional numerical study on the nonlinear behaviour of an electrically charged jet of Oldroyd-B viscoelastic, Taylor–Melcher leaky dielectric liquid is carried out. The effect of surface charge level, axial wavenumber and finite conductivity on the nonlinear evolution of the jet is investigated. Different structures including beads-on-a-string with/without satellite droplets, quasi-spikes and spikes are detected, and their domains in the plane of the non-dimensional axial wavenumber and the electrical Bond number are illustrated. The underlying mechanisms in the formation of the structures are examined. It is found that tangential electrostatic force plays a key role in the formation of a quasi-spike structure. Decreasing liquid conductivity may lead to a decrease in the size of satellite droplets or even the complete removal of them from a beads-on-a-string structure, induce the transition from a beads-on-a-string to a quasi-spike structure or postpone the appearance of a spike. On the other hand, finite conductivity has little influence on filament thinning in a beads-on-a-string structure, owing to the fact that the electrostatic forces are of secondary importance compared with the capillary force. The difference between the finite conductivity, large conductivity and other cases is elucidated. An experiment is carried out to observe spike structures.

Numerical Study of MHD Viscoelastic Fluid Flow with Binary Chemical Reaction and Arrhenius Activation Energy

2017 ◽  
Vol 15 (1) ◽  
Author(s):  
M. Mustafa ◽  
A. Mushtaq ◽  
T. Hayat ◽  
A. Alsaedi
Keyword(s):  
Activation Energy ◽  
Fluid Flow ◽  
Chemical Reaction ◽  
Viscoelastic Fluid ◽  
Numerical Study ◽  
Fluid Model ◽  
Constitutive Relations ◽  
Mathematical Formulation ◽  
Large Temperature ◽  
Temperature Function

Abstract Here we address the influence of heat/mass transfer on MHD axisymmetric viscoelastic fluid flow developed by an elastic sheet stretching linearly in the radial direction. Constitutive relations of Maxwell fluid model are utilized in mathematical formulation of the problem. Non-linear radiation heat flux is factored in the model which accounts for both small and large temperature differences. Chemical reaction effects with modified Arrhenius energy function are analyzed which are not yet explored for viscoelastic fluid flows. Highly accurate numerical computations are performed. Our computations show S-shaped profiles of temperature function in case of sufficiently large temperature differences. Species concentration increases when activation energy for chemical reaction is increased. However, both chemical reaction rate and temperature gradient tend to reduce the solute concentration.

Momentum equation for straight electrically charged jet

2011 ◽  
Vol 32 (12) ◽  
pp. 1515-1524 ◽  
Author(s):  
Ruo-jing Zhang ◽  
S. H. Hou ◽  
C. K. Chan
Keyword(s):  
Momentum Equation ◽  
Electrically Charged Jet ◽  
Electrically Charged

scholarly journals Numerical Study on the Characteristics of Boger Type Viscoelastic Fluid Flow in a Micro Cross-Slot under Sinusoidal Stimulation

Entropy ◽  
2020 ◽  
Vol 22 (1) ◽  
pp. 64
Author(s):  
Chao Yuan ◽  
Hong-Na Zhang ◽  
Li-Xia Chen ◽  
Jun-Long Zhao ◽  
Xiao-Bin Li ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Natural Frequency ◽  
Viscoelastic Fluid ◽  
Numerical Study ◽  
Nonlinear Effects ◽  
Weissenberg Number ◽  
Stimulation Frequency ◽  
External Stimulation ◽  
Inlet Velocity ◽  
The Cross

The cross-slot geometry plays an important role in the study of nonlinear effects of viscoelastic fluids. The flow of viscoelastic fluid in a micro cross-slot with a high channel aspect ratio (AR, the ratio of channel depth to width) can be divided into three types, which are symmetric flow, steady-state asymmetric flow and time-dependent flow under the inlet condition with a constant velocity. However, the flow pattern of a viscoelastic fluid in the cross-slot when a stimulation is applied at inlets has been rarely reported. In this paper, the response of cross-slot flow under an external sinusoidal stimulation is studied by numerical simulations of a two-dimensional model representing the geometry with a maximum limit of AR. For the cases under constant inlet velocity conditions, three different flow patterns occur successively with the increase of Weissenberg number (Wi). For the cases under sinusoidal varying inlet velocity conditions, when the stimulation frequency is far away from the natural frequency of a viscoelastic fluid, the frequency spectrum of velocity fluctuation field shows the characteristics of a fundamental frequency and several harmonics. However, the harmonic frequency disappears when the stimulation frequency is close to the natural frequency of the viscoelastic fluid. Besides, the flow pattern shows spatial symmetry and changes with time. In conclusion, the external stimulation has an effect on the flow pattern of viscoelastic fluid in the 2D micro cross-slot channel, and a resonance occurs when the stimulation frequency is close to the natural frequency of the fluid.

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