Novel Thermal Properties of Nanostructured Materials

Chang

Applied Mathematical Modelling

et al. 2015

In this paper, the lattice Boltzmann method is applied to investigate the natural and mixed convection of Al 2 O 3 /water nanofluids in a square enclosure. The Rayleigh number is considered from 10 3 to 10 6 to present the buoyancy effects. In mixed convection problems, the Richardson number representing the importance of natural convection relative to the forced convection is set to Ri=1, 5, and 10. Numerical results show that the convective heat transfer effects of nanofluids are higher than that of the base fluid. Increasing the nanoparticle volume fraction up to 4% can cause the averaged Nusselt number of the hot wall an increase about 5%~7% in natural convection and 9%~13% in mixed convection respectively. In natural convection, the streamlines and temperature contours are found to be slightly changed by adding nanoparticles into water. But In mixed convection, significant differences are obtained because the influence of adding nanoparticles on the properties of nanofluids is enlarged by the force convection effects.

Section: Resultsmentioning

confidence: 99%

“…(c) (d) Figure 2. Streamlines in the cases of natural convection for air at Ra= (a) 3 10 , (b) 4 10 , (c) 5 10 and (d) 6 10 .…”

Section: Resultsunclassified

Section: Verificationmentioning

confidence: 95%

Section: Mixed Convection Of Nanofluids In a Square Enclosurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Lattice Boltzmann simulation for mixed convection of nanofluids in a square enclosure

Chang

Applied Mathematical Modelling

et al. 2015

Three‐dimensional boundary layer flow over a rotating disk with power‐law stretching in a nanofluid containing gyrotactic microorganisms

Geng

et al. 2017

Heat Trans. Asian Res.

The nanofluid model containing microorganisms over a rotating disk with power‐law stretching is constructed in this paper. The combined effects of nanoparticles and microorganisms in nanofluid are investigated by solving the governing equations numerically. The numerical solutions of the skin friction coefficient and local Nusselt number are in agreement with the corresponding previously published results. The quantities of physical interest are graphically presented and discussed in detail. It is found that the power‐law stretching index has produced profound influence on the flow as well as the heat and mass transfer.

Effects of the viscous dissipation and chemical reaction on Casson nanofluid flow over the permeable stretching/shrinking sheet

2020

A steady two-dimensional Casson nanofluid flow over the permeable stretching/shrinking sheet along the viscous dissipation and the chemical reaction is studied in this article. The convective boundary condition is incorporated in energy equation. Similarity variables are applied to convert the governing partial differential equations into ordinary differential equations. The numerical solutions of the equations are obtained by using the shooting method with Maple implementation. The numerical findings indicate occurrence of the dual solutions for a certain range of stretching/ shrinking and suction parameters. Therefore, a stability analysis is done to find the solution that is stable and physically realizable. The effects of the pertinent physical parameters on velocity, temperature, and concentration profiles are investigated graphically. Numerical results of various parameters involved for skin friction coefficient, the local Nusselt as well as Sherwood numbers are determined and also discussed in detail. The Casson and suction parameters decrease the velocity in the first solution, whereas they increase it in the second solution. The rate of heat transfer increases in both solutions with an increment in Eckert number, Biot number, thermophoresis, and Brownian motion parameters. Thermophoresis and Brownian motion parameters show opposite behavior in the nanoparticle's concentration. The nanoparticle concentration decreases in both solutions with increment in Schmidt number, Brownian motion, and chemical reaction parameters. K E Y W O R D S Casson nanofluid, chemical reaction, convective boundary conditions, viscous dissipation 1 | INTRODUCTIONThe boundary layer flow of the incompressible fluids on the stretching and shrinking sheets has attracted much attention from the researchers, as it has many applications in industrial and the engineering processes, such as polymer extrusions, cooling of electronic devices through fans, nuclear reactors, wire drawing, shrinking swell behaviors, capillary effects in the small pores, and shrinking film. The main aim of selecting different sheets is to produce a better quality sheet that generally depends on the rate of cooling. As opposed to the stretching sheet, in shrinking case, the flow on the boundary is observed toward a fixed point. The importance of the fluid flows in the fluid mechanics have inspired many researchers to study all types of fluids from different physical point of views over various types of surfaces. Crane 1 studied the stretching sheet flow problem for the first time and found analytical solutions to the Navier-Stokes equations. Then, many other researchers 2-5 worked on the stretching sheet with different physical features. However, Miklavcic and Wang 6 for the first time discussed flow on shrinking sheet while studying the liquid films flow on the unsteady stretching surface. Fang 7 analyzed the boundary layer flow on the shrinking sheet through the power law velocity. Later, Wang 8 mentioned that at large shrinking rates, there exists nonexistenc...