Engineering International

9-20

Authors: Nguyen Thanh Hao

This paper presents development of k- turbulence model which can be applied for non-homogeneous two-phase turbulent flows. The improvement of governing equations of k- turbulence model is based on the decomposition of the two-phase flows into the gas phase and the second phase. Thus, the turbulent kinetic energy k and the turbulent dissipation rate  variables in k- two-equation model are substituted by the turbulent kinetic energy kg of the gas phase, the turbulent kinetic energy kp of the second phase, the turbulent dissipation rate g of the gas phase and the turbulent dissipation rate p of the second phase. The new turbulence model is kg-kp-g-p four-equation model which can be used to solve all of two-phase flows in nature studies and engineering applications.

28-37

Authors: Md. Alamgir Kabir; Rumelia Murshed; Ummul Husnaeen; Zahid Hasan Mahmood

Electronic devices and integrated systems are reduced to the size of micron and nanometer level and it becomes particularly important to predict the thermal transport properties of the components. Because of a unique structure and novel properties of carbon nanotubes (CNTs) have attracted significant attention. In this article, thermal transport properties of single wall CNTs (SWCNTs) are introduced. Combining equilibrium and non-equilibrium molecular dynamics with carbon potentials, we have studied the thermal conductivity of carbon nanotubes and its dependence on temperature. Phonon conduction depends on band gaps as well as thermal contact resistance of metallic CNTs, governed by phonon scattering and it shows evidence of 1-D quantization of the phonon band structure. We have studied here the thermal conductivity of single wall nanotubes dependence on chirality structure, dimensions of tubes, defects and vacancies in tubes. We found that the single wall carbon nanotubes have very high thermal conductivity comparable to diamond crystal and in-plane graphite sheet.

43-62

Authors: Mohammad Ali; Mohammad Shah Alam

The Hall effects on the steady MHD boundary layer flow of an incompressible fluid of combined heat and mass transfer over a moving inclined plate in a porous media with suction and viscous dissipation has studied. An external magnetic field is applied perpendicular to the surface and the fluid motion is subjected to a uniform suction and injection. A closed form solutions of the equations governing the flow are obtained for the velocity, secondary velocity, and temperature and concentration profiles. The dimensionless governing equations are solved using R-K method along with shooting technique. The velocities, temperature and concentration profiles are presented graphically for different values of governing flow parameters. The results presented graphically illustrate that primary velocity field decrease due to increase of magnetic parameter, angle of inclination, permeability parameter and suction parameter while secondary velocity also decrease for magnetic parameter, Hall parameter and permeability parameter .Other parameters increase the velocities of the fluid flow. Temperature field increases in the presence of Magnetic parameter, Grashof number, Modified Grashof number and permeability parameter and decreases for Prandlt number and suction parameter. Also, concentration profiles decreases for increasing the values of magnetic parameter, Hall parameter, Schmid number and suction parameter but there is no effect on concentration of the remaining parameters. Also the skin friction coefficient, the local Nusselt number and the local Sherwood number are presented in Tables 1-3.