On the motion of Newtonian and non-Newtonian liquid drops

Aminzadeh, M.; Maleki, A.; Firoozabadi, Bahar; Afshin, Hossein

doi:10.1016/j.scient.2011.09.022

Cited by 19 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Previous Work and Research Gapsupporting

confidence: 81%

“…For instance, Winnikow and Chao [23] reported extensive drag results on an organic Newtonian drop falling in water based on the measurement of the terminal velocity. More recently, a similar study was reported by Aminzadeh et al [24] To the best of our knowledge, the first approximate solution of momentum equation in the creeping flow regime for Bingham plastic fluids was proposed by Bhavaraju et al [25] They utilized the perturbation method to linearize the viscous terms and concluded that both drag and mass transfer are seen to be higher in Bingham plastic fluids with reference to Newtonian fluids. Furthermore, they proposed expressions for drag coefficient and Sherwood number as follows:…”

Section: Previous Work and Research Gapmentioning

confidence: 53%

See 1 more Smart Citation

Stability criteria and convective mass transfer from the falling spherical drops, part I: Bingham plastic fluids

2021

View full text Add to dashboard Cite

This work deals with the flow and mass transfer around a falling spherical drop in Bingham plastic fluids. Bubbles, drops, and particles are often dispersed in a suspending fluid of non-Newtonian nature. For example, suspensions of particles in a polymer solution are used in hydraulic fracturing slurries and swarms of bubbles are used in airlift bioreactors containing various biomacromolecules, as well as in foam production, degassing, and devolatilization of polymer melts. Governing equations for momentum and mass transfer and the Bingham constitutive equation are solved over a wide range of dimensionless groups as Reynolds number, 1 ≤ Re ≤ 150; Schmidt number, 1 ≤ Sc ≤ 100 ; Bingham number, 0 ≤ Bn ≤ 50 ; and viscosity ratio (0.1 and 10).The local underline transport processes are expressed using streamlines, concentration contours, and sheared and un-sheared regions, whereas the average transport quantities are reported in terms of drag coefficient, critical yieldstress parameter, and Sherwood number. A co-existence of sheared and unsheared regions occurs within the flow domain due to the fluid-yield stress.The sheared regions progressively diminish with the increasing value of the Bingham number. On the other hand, inertial effects (increasing Re) promotes the expansion of the sheared region in the flow domain. The new modified dimensionless groups are defined by re-scaling the governing equations based on the effective viscosity of the fluid. Finally, the present numerical values of the drag and average Sherwood number are correlated using the new modified dimensionless numbers.

show abstract

Section: Previous Work and Research Gapsupporting

confidence: 81%

Section: Previous Work and Research Gapmentioning

confidence: 53%

Stability criteria and convective mass transfer from the falling spherical drops, part I: Bingham plastic fluids

2021

View full text Add to dashboard Cite

show abstract

“…Droplets of deionised water, with a density of = 995 −3 and surface tension = 72 × 10 −3 −1 at 21 °C with volumes between 3.56 and 5.84 μl were generated by squeezing the nozzle until the droplet is detached under its gravity from the edge of a needle (BD Microlance). For each needle, the droplet size was calculated using the approach proposed by Aminzadeh et al [44] and was repeatable with <5%. By adjusting the drop height, the impact velocity was varied between 1.4 and 2 m/s.…”

Section: B Droplet Bouncing and Imagingmentioning

confidence: 99%

Acoustic Waves for Active Reduction of Contact Time in Droplet Impact

Biroun

Tao

et al. 2020

Phys. Rev. Applied

View full text Add to dashboard Cite

Minimising droplet impact contact time is critical for applications such as self-cleaning, antierosion or anti-icing. Recent studies have used texturing of surfaces to split droplets during impact or inducing asymmetric spreading, but these require specifically designed substrates which cannot be easily reconfigured. A key challenge is to realise an effective reduction in contact time during droplet impingement on a smooth surface without texturing but with an active and programmable control. Our experimental results show that surface acoustic waves (SAWs), generated at a location distant from a point of droplet impact, can be used to minimise contact time by as much as 35% without requiring a textured surface. Besides, the ability to switch on and off the SAWs means that reduction in droplet impact contact time on a surface can be controlled in a programmable manner. Moreover, our results show that by applying acoustic waves, the impact regime of the droplet on the solid surface can be changed from deposition or partial rebound to complete rebound. To study the dynamics of the droplet impact, we developed a numerical model for the multi-phase flow and simulated different droplet impingement scenarios. Numerical results revealed that the acoustic waves could be used to modify and control the internal velocity fields inside the droplet. By breaking the symmetry of the internal recirculation patterns inside the droplet, the kinetic energy recovered from interfacial energy during the retraction process is increased, and the droplet can be fully separated from the surface with a much shorter contact time. Our work opens up opportunities to use SAW devices to minimise the contact time, change the droplet impact regime and program/control the droplet's rebounding on smooth/planar and curved surfaces as well as rough/textured surfaces.

show abstract

“…In general, the main external forces applied to a forming drop are interfacial tension and drag, which oppose the drop breakup, and the gravity as well as kinetic forces that tend to separate the drop from the needle. To better comprehend and compare the magnitude of the mentioned forces, their values (in terms of N) are calculated approximately as a sample for the drop of 0.75% CMC without a surfactant at 400 ms remaining to breakup (Figure ) using eqs –, where ρ d is the density of the drop phase, g is gravitational acceleration, V is the drop volume, which is calculated by the image processing method, u is the velocity of fluid exiting the needle, Q is the flow rate of the drop phase, σ is the interfacial tension, θ is the angle between the drop surface and the needle, r is the radius of the forming drop, u drop is the growing velocity of the drop, which is measured using the data presented in Figure a, μ c is the viscosity of air, and μ d is the zero-shear viscosity of the drop phase. …”

Section: Resultsmentioning

confidence: 99%

Influences of Polymer–Surfactant Interaction on the Drop Formation Process: An Experimental Study

et al. 2021

View full text Add to dashboard Cite

The interaction between polymer and surfactant molecules affects the physical properties of liquids, which could be of great importance in an abundance of processes related to drop formation. Polymer and surfactant concentration is a factor that dramatically impacts the shape of molecular networks formed in the fluid bulk and the characteristics of a forming drop. In this study, the deformation and detachment of aqueous carboxymethyl cellulose (CMC) solutions’ drops containing different concentrations of sodium dodecyl sulfate (SDS) are studied experimentally. Our purpose is to determine the effects of CMC and SDS concentrations on the parameters related to the formation process, including drop length, minimum neck thickness, and formation time. Our results clearly show that the increment of the SDS amount at a constant low CMC concentration increases the drop detachment length and results in a slower thinning process. However, at higher CMC concentrations, the drop limiting length reaches a maximum, indicating the effects of disintegration of molecular structures as the SDS amount exceeds the critical concentration. Moreover, the drop formation time is found to decrease with the increment of the SDS concentration, which could be attributed to the reduction of dynamic interfacial tension.

show abstract

On the motion of Newtonian and non-Newtonian liquid drops

Cited by 19 publications

References 31 publications

Stability criteria and convective mass transfer from the falling spherical drops, part I: Bingham plastic fluids

Stability criteria and convective mass transfer from the falling spherical drops, part I: Bingham plastic fluids

Acoustic Waves for Active Reduction of Contact Time in Droplet Impact

Influences of Polymer–Surfactant Interaction on the Drop Formation Process: An Experimental Study

Contact Info

Product

Resources

About