Detection of nanoparticles suspended in a light scattering medium

Intentionally intensifying the light scattering of medium molecules can allow the detection of suspended nanoparticles under conditions not suitable for conventional optical microscopies or laser particle counters. Here, we demonstrate how the collective light scattering of medium molecules and nanoparticles is imaged in response to the power, frequency, and oscillating direction of the incident light wave electric field, and how this response can be used to distinguish between nanoparticles and microparticles, such as viruses or bacteria. Under conditions that the medium light scattering is intensified, suspended nanoparticles appear as magnified shiny moving dots superimposed on the quasi-steady background of medium light scattering. Utilizing the visual enlargement resulted from the enhanced light scattering and possible light interference, we can detect directly suspended nanoparticles that are much smaller than visible light wavelengths even in unopened water bottles or other large containers. This suggests new approaches for detecting nanoparticles with many potential applications.

Enhancement of heat transfer for boiling in nanofluid

The paper considers heat transfer during boiling of subcooled water with suspended nanoparticles Al2O3 using a suspension from 0.32% to 4%. On a spherical model, the local heat flux per unit area was measured by the method of gradient heatmetry for model temperature of 464 °C and water temperature of 64 °C. The results are compared with the data obtained at the same temperature conditions for pure water. Enchancement of heat transfer was revealed in the entire concentration range - with a maximum at a particle concentration close to 1%.

MHD and Stability for Convective Flow of Micropolar Nanofluid over a Moving and Vertical Permeable Plate

This work mainly studies the effect of the magnetic field, the suction /injection, the Brownian and thermphorese diffusions and the stability on heat transfer in a laminar boundary layer flux of micropolar nanofluids flow adjacent to moving vertical permeable plate. The appropriate governing equations developed are reduced by the transformation of similarity which are solved using the finite difference method that implements the 3-stage Lobatto collocation formula. A parametric study of the physical parameters is carried out to show their influence on the different profiles. The results show that the microrotation of the suspended nanoparticles and the presence of the magnetic field become important on the heat transfer with good chemical stability of the micropolar nanofluids.

Effects of Stenosis and Dilatation on Flow of Blood Mixed with Suspended Nanoparticles: A Study Using Homotopy Technique

The paper deals with a theoretical study on blood flow in a stenosed segment of an artery, when blood is mixed with nano-particles. Blood is treated here as a couple stress fluid. Stenosis is known to impede blood flow and to be the cause of different cardiac diseases. Since the arterial wall is weakened due to arterial stenosis, it may lead to dilatation /aneurysm. The homotopy perturbation technique is employed to determine the solution to the problem for the case of mild stenosis. Analytical expressions for velocity, shear stress at the wall, pressure drop, and flow resistance are derived. The impact of different physical constants on the wall shear stress and impedance of the fluid is examined by numerical simulation. Streamline patterns of the nanofluid are investigated for different situations.

Enhanced thermal conductivity of nanofluids by introducing Janus nanoparticles

The addition of nanoparticles to a base fluid (i.e., nanofluids) is an effective strategy to achieve a higher thermal conductivity of a fluid. In a common nanofluid, the suspended nanoparticles...

Flow of Jeffrey Fluid over a Horizontal Circular Cylinder with Suspended Nanoparticles and Viscous Dissipation Effect: Buongiorno Model

Mathematical model of Jeffrey fluid describes the property of viscoelastic that clarifies the two components of relaxation and retardation times. Nevertheless, the poor thermal performance of Jeffrey fluid has been a key issue facing the public. This issue can be accomplished by the use of nanofluid that has superior thermal performance than the conventional fluids. A better cooling rate in industry is in fact not appropriate to attain by the thermal conductivity of the conventional fluids. On that account, the present study aims to delve into the impact of viscous dissipation and suspended nanoparticles on mixed convection flow of Jeffrey fluid from a horizontal circular cylinder. A concise enlightenment on the separation of boundary layer flow is included and discussed starting from the lower stagnation point flow up to the separation point only. The non-dimensional and non-similarity transformation variables are implemented to transform the dimensional nonlinear partial differential equations (PDEs) into two nonlinear PDEs, and then tackled numerically through the Keller-box method. Representation of tabular and graphical results are executed for velocity and temperature profiles as well as the reduced skin friction coefficient, Nusselt number and Sherwood number to investigate the physical insight of emerging parameters. It was found that the incremented ratio of relaxation to retardation, Deborah number and Eckert number have delayed the boundary layer separation up to 120o

Three-Disperse Magnetorheological Fluids Based on Ferrofluids Induced Modification of Sedimentation by Addition of Nanoparticles

The effect of mixing suspended nanoparticles into a bi-disperse magneto-rheological fluid on sedimentation phenomena is explored. A reference bi-disperse MRF has been modified using a ferrofluid containing magnetite nanoparticles of two shapes (spheres or hexagonal platelets) suspended in paraffin-oil as carrier fluid. The reference MRF was prepared with a mixture of two diameter sizes for the micrometric particles. The reference MRF was also prepared using two different grades of carbonyl-iron micrometric particles (herein these will be referred to as HARD and SOFT), which differ each other for their mechanical properties. The experiment monitored the evolution with time of the sediment-supernatant interface. This experiment showed that the presence of nanoparticles (particularly the spherical ones) slows down the sedimentation effects in terms of ratio and rate, independently of the other characteristics of the fluid. This study also showed that fluids based on SOFT carbonyl iron powders, in presence of nanospheres, are more stable than HARD carbonyl iron powder based fluids, since their sedimentation rate slows down in the long term. At the same time, HARD particle-based magnetorheological fluids show smaller sedimentation ratios than SOFT based fluids.