Nanofluid Droplet Evaporation Kinetics and Wetting Dynamics on Flat Substrates

2009 ◽  
Vol 7 ◽  
pp. 75-80 ◽  
Author(s):  
J.Ross Moffat ◽  
Khellil Sefiane ◽  
Martin E.R. Shanahan
Keyword(s):  
Contact Line ◽  
Particle Concentration ◽  
Nano Particles ◽  
Nano Particle ◽  
Stick Slip ◽  
Particle Accumulation ◽  
Contact Line Pinning ◽  
Base Liquid ◽  
Particle Addition ◽  
Evaporation Kinetics

An experimental investigation into the evaporation of sessile nanofluid droplets is reported in this paper. The effect of nano-particle addition on the evaporative behaviour is studied using ethanol and Titanium Oxide nano-particles. The results show that a distinct ‘stick-slip’ pinning behaviour is observed when nano-particles are added to the base liquid. Increasing the nano-particle concentration was found to enhance the ‘stick-slip’ behaviour. This behaviour is attributed to the effects of evaporatively driven particle accumulation near the contact line. This in turn leads to an increase in localised viscosity, and an enhancement of contact line pinning.

scholarly journals Numerical Forced Convection Heat Transfer of Nanofluids over Back Facing Step and Through Heated Circular Grooves

2021 ◽  
Vol 8 (4) ◽  
pp. 597-610
Author(s):  
Ali Hussein Abdulkarim ◽  
Muhammad Asmail Eleiwi ◽  
Tahseen Ahmad Tahseen ◽  
Eyub Canli
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Heat Flux ◽  
Reynolds Number ◽  
Particle Concentration ◽  
Volume Fraction ◽  
Aluminium Oxide ◽  
Nano Particles ◽  
Bottom Surface ◽  
Nano Particle

Backward facing step arrangement is a classical case for fluid dynamics and heat transfer research. It is well characterized and therefore, used for benchmarking. However, ongoing studies reveal that the geometry also provide advantages in industry, especially in combustion and burners. This work utilizes computational fluid dynamics to investigate a specific laminar back facing step flow heat transfer case. Aluminium oxide nano particles are considered as an additive to water base fluid, forming nanofluid with different volumetric concentrations. Laminar flow passes a back facing step and encounters three circular grooves at bottom surface. All surfaces are adiabatic except the grooves. Constant surface temperature applies to the grooves. According to the simulation results, a separation bubble after back facing step and a reattachment point occur. Grooves alter expected wake due to physical and thermal interference. Investigation parameters are nano-particle concentration and Reynolds number. Reynolds number changes between 10 and 250. Nano particle volume fraction percentage changes between 2 and 6 percent. Sectional heating downstream of the step poses interesting heat flux in the presence of Aluminium oxide nano-particle concentrations. There is a pseudo-linear relationship between parameters and heat transfer. Combined effects of enhanced thermal conductivity and secondary flow structures are seen. As expected, thermal convection increases as flow velocity and nano-particle concentrations increase. Heat flux and accordingly Nusselt number are highly affected from Reynolds number since flow structure changes dramatically. Also, direct proportion is seen between nano-particle concentration and enhanced convection.

scholarly journals Heat Transfer Enhancement by the Usage of Low Concentration MgO-Water Nanofluid

2019 ◽  
Vol 9 (1) ◽  
pp. 1985-1990
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Base Fluid ◽  
Particle Concentration ◽  
Volume Concentration ◽  
Nano Particles ◽  
Distilled Water ◽  
Nano Particle ◽  
Transfer Enhancement ◽  
Fluid Properties

The current tentative work proposes the convective heat transfer enhancement by means of using low concentrations MgO-Water nanofluid flowing via tube. Nanofluid is the rising heat transfer fluids which consists solid nano-sized particles suspended in base fluid. Total three volume concentrations (0.005%, 0.01%, and 0.05%) and four unique sizes of nano particle (7 nm, 40nm, 60 nm, 100nm) are used to prepare nanofluid with distilled water. There are different correlations available to find nano fluid properties but they are not applicable as these are dependent on number of parameter like base fluid properties, particle size, shape and concentration of nano particle in a base fluid. Therefore actual measurements of different properties are carried out. Experimental investigation is executed for different Reynolds no, particle concentration and different size of nano particle. It is experimental that average heat transfer augmentation of 44.73% is obtained for 0.05% volume concentration (40 nm size) as compared to distilled water. It is found that there is augmentation of heat transfer with amplifying in particle concentration and reducing in size of nano particles. The typical improvement in Nusselt number for particle sizes of 7 nm, 40 nm, 60 and 100nm are found to be 37.76%, 36.53%, 35.15% and 32.26% respectively as compared to distilled water. It is found that as volume concentration increases and size of nanoparticle decreases there is augmentation of heat transfer.

Mechanical Properties of Glass–Fiber Polyester Reinforced Composites Filled with Nanometer Al2O3 Particles

2012 ◽  
Vol 586 ◽  
pp. 199-205
Author(s):  
Fatemeh Alavi ◽  
Ali Ashrafi
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Fracture Behavior ◽  
Failure Modes ◽  
Glass Fibers ◽  
Weight Percent ◽  
Mechanical Tests ◽  
Nano Particles ◽  
Nano Particle ◽  
Particle Addition

In this research the effects of the nano-particle additions and two different fabric architectures of knitted E-glass fibers on the mechanical properties of polyester fiberglass composites were investigated. The particles selected was 50 nanometer in size Al2O3 particles. E-glass fibers were knitted using two different molds by two different arrangements. Specimens were machined and mechanical tests were conducted as per the accepted test standard. Tension, impact and fracture properties were measured and their associated failure modes were compared with each other. Fracture behavior of specimens with and without nano-particle addition in unidirectional tensile test was studied using Scanning Electron Microscopy (SEM). Results obtained showed that tensile strength of the composite is significantly dependent on nano-particle addition and E-glass fiber architecture. Addition of 0.2 weight percent nano-particles enhances the tensile properties of polyester fiberglass composites. It was found that fracture behavior of composite depends strongly on nano-particle addition.

scholarly journals Exact Analytical Solution of the Peristaltic Nanofluids Flow in an Asymmetric Channel with Flexible Walls and Slip Condition: Application to the Cancer Treatment

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Abdelhalim Ebaid ◽  
Emad H. Aly
Keyword(s):  
Blood Vessel ◽  
Cancer Treatment ◽  
Particle Concentration ◽  
Exact Analytical Solution ◽  
Peristaltic Flow ◽  
Nano Particles ◽  
Nano Particle ◽  
Slip Effects ◽  
Flexible Walls ◽  
The Mathematical Model

In the cancer treatment, magnetic nanoparticles are injected into the blood vessel nearest to the cancer’s tissues. The dynamic of these nanoparticles occurs under the action of the peristaltic waves generated on the flexible walls of the blood vessel. Studying such nanofluid flow under this action is therefore useful in treating tissues of the cancer. In this paper, the mathematical model describing the slip peristaltic flow of nanofluid was analytically investigated. Exact expressions were deduced for the temperature distribution and nano-particle concentration. In addition, the effects of the slip, thermophoresis, and Brownian motion parameters on the temperature and nano-particle concentration profiles were discussed and further compared with other approximate results in the literatures. In particular, these results have been obtained at the same values of the physical examined parameters that was considered in Akbar et al., “Peristaltic flow of a nanofluid with slip effects,” 2012. The results reveal that remarkable differences are detected between the exact current results and those approximately obtained in the literatures for behaviour of the temperature profile and nano-particles concentration. Accordingly, the current analysis and results are considered as optimal and therefore may be taken as a base for any future comparisons.

Numerical Simulation for Microconvection Around Nano-Particle With Brownian Motion in Liquid

2003 ◽  
Author(s):  
B. X. Wang ◽  
H. Li ◽  
X. F. Peng ◽  
L. X. Yang
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Brownian Motion ◽  
Numerical Model ◽  
Temperature Gradient ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Nano Particles ◽  
Analytic Method ◽  
Nano Particle

The development of a numerical model for analyzing the effect of the nano-particles’ Brownian motion on the heat transfer is described. By using the Maxwell velocity distribution relations to calculate the most possible velocity of fluid molecules at certain temperature gradient location around the nano-particle, the interaction between fluid molecules and one single nano-particle is analyzed and calculated. Based on this, a syntonic system is proposed and the coupled effect that Brownian motion of nano-particles has on fluid molecules is simulated. This is used to formulate a reasonable analytic method, facilitating laboratory study. The results provide the essential features of the heat transfer process, contributed by micro-convection to be considered.

Droplet spreading and absorption on rough, permeable substrates

2015 ◽  
Vol 784 ◽  
pp. 465-486 ◽  
Author(s):  
Leonardo Espín ◽  
Satish Kumar
Keyword(s):  
Surface Roughness ◽  
Contact Line ◽  
Nonlinear Evolution ◽  
Precursor Film ◽  
Radial Coordinate ◽  
Droplet Spreading ◽  
Liquid Spreading ◽  
Line Region ◽  
Influence Of Substrate ◽  
Contact Line Pinning

Wetting of permeable substrates by liquids is an important phenomenon in many natural and industrial processes. Substrate heterogeneities may significantly alter liquid spreading and interface shapes, which in turn may alter liquid imbibition. A new lubrication-theory-based model for droplet spreading on permeable substrates that incorporates surface roughness is developed in this work. The substrate is assumed to be saturated with liquid, and the contact-line region is described by including a precursor film and disjoining pressure. A novel boundary condition for liquid imbibition is applied that eliminates the need for a droplet-thickness-dependent substrate permeability that has been employed in previous models. A nonlinear evolution equation describing droplet height as a function of time and the radial coordinate is derived and then numerically solved to characterize the influence of substrate permeability and roughness on axisymmetric droplet spreading. Because it incorporates surface roughness, the new model is able to describe the contact-line pinning that has been observed in experiments but not captured by previous models.

scholarly journals Advancing liquid contact line on visco-elastic gel substrates: stick-slip vs. continuous motions

Soft Matter ◽  
2013 ◽  
Vol 9 (2) ◽  
pp. 454-461 ◽  
Author(s):  
Tadashi Kajiya ◽  
Adrian Daerr ◽  
Tetsuharu Narita ◽  
Laurent Royon ◽  
François Lequeux ◽  
...  
Keyword(s):  
Contact Line ◽  
Stick Slip

STUDYING THE CONTACT POINT AND INTERFACE MOVING IN A SINUSOIDAL TUBE WITH LATTICE BOLTZMANN METHOD

2001 ◽  
Vol 15 (09) ◽  
pp. 1287-1303 ◽  
Author(s):  
HAI-PING FANG ◽  
LE-WEN FAN ◽  
ZUO-WEI WANG ◽  
ZHI-FANG LIN ◽  
YUE-HONG QIAN
Keyword(s):  
Boundary Conditions ◽  
Contact Line ◽  
Lattice Boltzmann ◽  
Complex Geometry ◽  
Contact Point ◽  
Point Contact ◽  
Immiscible Fluids ◽  
Lattice Boltzmann Model ◽  
Stick Slip ◽  
Bounce Back

The multicomponent nonideal gas lattice Boltzmann model by Shan and Chen (S-C) is used to study the immiscible displacement in a sinusoidal tube. The movement of interface and the contact point (contact line in three-dimension) is studied. Due to the roughness of the boundary, the contact point shows "stick-slip" mechanics. The "stick-slip" effect decreases as the speed of the interface increases. For fluids that are non-wetting, the interface is almost perpendicular to the boundaries at most time, although its shapes at different position of the tube are rather different. When the tube becomes narrow, the interface turns a complex curves rather than remains simple menisci. The velocity is found to vary considerably between the neighbor nodes close to the contact point, consistent with the experimental observation that the velocity is multi-values on the contact line. Finally, the effect of three boundary conditions is discussed. The average speed is found different for different boundary conditions. The simple bounce-back rule makes the contact point move fastest. Both the simple bounce-back and the no-slip bounce-back rules are more sensitive to the roughness of the boundary in comparison with the half-way bounce-back rule. The simulation results suggest that the S-C model may be a promising tool in simulating the displacement behaviour of two immiscible fluids in complex geometry.

scholarly journals Moving contact line on chemically patterned surfaces

2008 ◽  
Vol 605 ◽  
pp. 59-78 ◽  
Author(s):  
XIAO-PING WANG ◽  
TIEZHENG QIAN ◽  
PING SHENG
Keyword(s):  
Contact Line ◽  
Critical Value ◽  
Diffuse Interface ◽  
Patterned Surfaces ◽  
Fluid Interface ◽  
Two Phase ◽  
Stick Slip ◽  
Moving Contact Line ◽  
Moving Contact ◽  
Wetting Fluid

We simulate the moving contact line in two-dimensional chemically patterned channels using a diffuse-interface model with the generalized Navier boundary condition. The motion of the fluid–fluid interface in confined immiscible two-phase flows is modulated by the chemical pattern on the top and bottom surfaces, leading to a stick–slip behaviour of the contact line. The extra dissipation induced by this oscillatory contact-line motion is significant and increases rapidly with the wettability contrast of the pattern. A critical value of the wettability contrast is identified above which the effect of diffusion becomes important, leading to the interesting behaviour of fluid–fluid interface breaking, with the transport of the non-wetting fluid being assisted and mediated by rapid diffusion through the wetting fluid. Near the critical value, the time-averaged extra dissipation scales as U, the displacement velocity. By decreasing the period of the pattern, we show the solid surface to be characterized by an effective contact angle whose value depends on the material characteristics and composition of the patterned surfaces.

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