CuO/WATER NANOFLUID FLOW OVER MICROSCALE BACKWARD-FACING STEP AND ANALYSIS OF HEAT TRANSFER PERFORMANCE

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Al2O3/water forced convection nanofluid flow was numerically studied in a duct with backward-facing step. Nanoparticle volume fraction was changed between 1%-5%. Diameter of nanoparticle was constant (dp=40 nm). The Reynolds number was increased from 100 to 500. The step and total height of the duct were 4.8 mm and 9.6 mm, respectively. The bottom wall, which was positioned after the step, was heated with 2000 W/m 2 and the rest of the walls were adiabatic. Nusselt number, velocity profiles and friction factor were investigated in detail. It was obtained that Nusselt number increases with increasing nanoparticle volume fraction and Reynolds number.

Section: Resultssupporting

confidence: 86%

A CFD INVESTIGATION OF Al2O3/WATER FLOW IN A DUCT HAVING BACKWARD-FACING STEP

Ekiciler¹

2018

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“…It can be seen from the figure that there is no significant effect of changing volume fractions of nanoparticles on Darcy friction factor in micro -channel as reported for Al2O3/Water and Al2O3/Water-EG nanofluids by Ref. [30][31][32]. Because at lower velocity values of fluid, the shear stress near the walls of micro-channel is higher values.…”

Section: Resultsmentioning

confidence: 57%

CFD ANALYSIS OF LAMINAR FORCED CONVECTIVE HEAT TRANSFER FOR TiO2/WATER NANOFLUID IN A SEMI-CIRCULAR CROSS-SECTIONED MICRO-CHANNEL

Ekiciler¹

2019

Self Cite

In this study, forced convection flow and heat transfer characteristics of TiO2/water nanofluid flow with different nanoparticle volume fractions (1.0%, 2.0%, 3.0% and 4.0%) in semi-circular cross-sectioned micro-channel was numerically investigated. The threedimensional study was conducted under steady state laminar flow condition where Reynolds number changing from 100 to 1000. CFD model has been generated by using ANSYS FLUENT 15.0 software based on finite volume method. The flow was under hydrodynamically and thermally developing flow condition. Uniform surface heat flux boundary condition was applied at the bottom surface of the micro-channel. The average and local Nusselt number and Darcy friction factor values were obtained using numerical results. Also, the effects of using nanofluid on local values of Nusselt number and Darcy friction factor were investigated. Numerical results indicate that the increasing of nanoparticle volume fraction of nanofluid, the average Nusselt number increases; however, there is no significant variation in average Darcy friction factor.

“…In this study, tetrahedral grids are used for the computational domain [18]. Nine grid resolutions (from extremely coarse to extremely fine) are employed to determine the appropriate grid for the case a of Figure 3.…”

Section: Grid Studymentioning

confidence: 99%

Mixing Enhancement in Electroosmotic Micromixers

Ghahfarokhi

Bayareh

Nadooshan

et al. 2021

Micromixers have important applications in various pharmaceutical and medical fields. In the present study, the enhancement of mixing index in electroosmotic micromixer with different geometries is investigated. The commercial software COMSOL Multiphysics 5.4 is employed to solve the mathematical models. The SIMPLEC algorithm is employed for coupling the velocity and pressure fields. A second-order upwind scheme is used to reduce the artificial diffusivity. The results show a remarkable effect of the electric field on the mixing efficiency. The optimum geometry is the one with no obstacle in the mixing chamber. For the optimum geometry, it is demonstrated that the mixing efficiency increases with the voltage, however there are optimum values for frequency and inlet velocity in which the micromixer exhibits its best performance. The optimum values of frequency and inlet velocity are 8 Hz and 0.1 mm/s, respectively. It is revealed that the micromixer with no obstacle can reach the mixing efficiency of about 97%.