Turbulent forced convection of nanofluid in a wavy channel using two phase model

Two phase mixture model is used to numerically simulate the turbulent forced convection of Al₂O₃-Water nanofluid in a channel with corrugated wall under constant heat flux. Both mixture and single phase models are implemented to study the nanofluid flow in such a geometry and the results have been compared. The effects of the volume fraction of nanoparticles, Reynolds number and amplitude of the wavy wall on the rate of heat transfer are investigated. The results showed that with increasing the volume fraction of nanoparticles, Reynolds number and amplitude of wall waves, the rate of heat transfer increases. Also the results showed that the mixture model yields to higher Nusselt numbers than the single phase model in a similar case.     

Numerical simulation of forced convection of nanofluid in a confined jet

In this paper two-dimensional incompressible water–Al₂O₃ nanofluid flow in a confined jet in the laminar flow regime is numerically investigated. A finite volume technique on a collocated grid is employed for discretizing the governing equations by applying the SIMPLE algorithm to link the pressure and velocity fields. The present computations are in a very good agreement with experimental results in open literature.     

Numerical investigation of boiling heat transfer in a quenching process of jet impingement considering solid temperature distribution

Boiling jet impingements are being widely used in various industries. Hence, a quenching jet impingement is simulated numerically. A solver code based on volume of fluid method was modified to analyze the effects of conjugation and mass transfer, and validated against an experimental study. Then, optimized cooling factor (OCF) was defined to involve temperature uniformity of the block and the cooling rate simultaneously. Subsequently, in laminar two-jet configurations, the effects of velocity inlet function, jet-to-surface and jet-to-jet spacing on standard temperature uniformity index (STUI) and OCF in a highly heated block were investigated. Heaviside function of time for the inlet velocity and periods of pulse between 0 and 0.2 were considered. Some remarkable results are achieved by the proposed configurations. In all cases with pulsating jets, improvements in STUI and OCF relative to pulse-free ones were observed; when V?=?0.4 m s^?1, OCF peaked at 2 in P?=?0.06, which was almost eight times greater than OCF of pulse-free configuration (OCF?=?0.24). As velocity decreased, the temperature uniformity improved; however, OCF showed the highest value at higher velocities occurring for lower periods of pulses. This happens because of more uniform temperature distribution in both plate sides and continual destroying film boiling layers generated on the surface. Also, in a jet-to-jet spacing of about one-third of the block length, for all plate lengths, optimal temperature uniformity with maximum OCF was obtained, due to formation of two stagnation points having the highest heat transfer rate by positioning in an ideal distance from each other.

     

Numerical simulation of magnetic drug targeting with Eulerian-Lagrangian model and effect of viscosity modification due to diabetics

The targeted drug delivery and targeted drug therapy transport a drug directly to the center of the disease under various conditions and thereby treat it deliberately without effects on the body. This paper studies the magnetic drug targeting (MDT) technique by particle tracking in the presence of magnetic field in bifurcation vessels of a healthy person and a diabetes patient. The Lagrangian particle tracking is performed to estimate particle behavior under effects of imposed magnetic field gradients along the bifurcation. The results show that the magnetic field increases the volume fraction of particle in the target region, and the efficiency of MDT on a patient with the diabetes disease is better than a healthy person. Also, for the higher magnetic numbers, the flow in the upper branch is strongly affected by the magnetic field.     

Numerical Simulation of Two Phase Turbulent Flow of Nanofluids in Confined Slot Impinging Jet

In this article, a numerical investigation is performed on flow and heat transfer of confined impinging slot jet, with a mixture of water and Al₂O₃ nanoparticles as the working fluid. Two-dimensional turbulent flow is considered and a constant temperature is applied on the impingement surface. The k ? ω turbulence model is used for the turbulence computations. Two-phase mixture model is implemented to study such a flow field. The governing equations are solved using the finite volume method. In order to consider the effect of obstacle angle on temperature fields in the channel, the numerical simulations were performed for different obstacle angles of 0° ? 60°. Also different geometrical parameters, volume fractions and Reynolds numbers have been considered to study the behavior of the system in terms of stagnation point, average and local Nusselt number and stream function contours. The results showed that the intensity and size of the vortex structures depend on jet- impingement surface distance ratio (H/W) and volume fraction. The maximum Nusselt number occurs at the stagnation point with the highest values at about H/W = 1. Increasing obstacle angle, from 15° to 60°, enhances the heat transfer rate. It was also revealed that the minimum value of average Nusselt number occurs in higher H/W ratios with decreasing the channel length.