Convection Boundary Layer Flows Over Needles and Cylinders in Viscous Fluids

Convection is the heat transfer process which is frequently encountered in environmental and engineering applications. In this study, the problems of steady laminar convection boundary layer flows over needles and cylinders immersed in an incompressible and viscous fluid are theoretically considered. The dimensional partial differential equations governing the boundary layer flows are first transformed into nondimensional equations. These equations are then transformed using non-similar transformation. Then, these transformed nonlinear systems of equations are solved using an implicit finite difference scheme known as the Keller-box method, which has been found to be very suitable in dealing with nonlinear and parabolic equations. The complete numerical method used in this study is programmed in Fortran. Numerical computations are carried out for various values of the dimensionless parameters of the problems, which include the Prandtl number Pr, the ratio of the major and minor axes of the cylinder bc=ac, the mixed convection parameter , the modified mixed convection parameter ^, the transverse curvature parameter , the parameter a representing the needle size and the viscosity/temperature parameter r. Numerical results presented in this study are the skin friction coefficient, the heat transfer coefficient, the local Nusselt number, the cylinder temperature as well as the velocity and temperature profiles. The obtained results show that the flow and the thermal characteristics are significantly influenced by these parameters

Similarity solutions for laminar convection boundary layer flows from a cone in a porous medium filled with a nanofluid.

The steady free and convection boundary layer flows from a vertical cone in a porous medium filled with water based nanofluids are numerically investigated using three different types of nanoparticles which are copper,alumina and titania

Unsteady Boundary Layer Separated Stagnation-Point Flow towards a Permeable Shrinking Sheet

A study of the unsteady separated stagnation-point flow with constant suction towards a shrinking sheet is presented. A similarity transformation reduces the governing partial differential equation to the third order nonlinear ordinary differential equation which the terms of unsteady effect are clearly shown. The problem is solved numerically where the influences of shrinking and suction parameters on flow are studied. It is found that two solutions exist, one representing an attached flow while the other a reverse flow. It is found that adequate suction is necessary for the solutions to exist

Developing e-counselling system

This paper introduces a Web-based Counselling System, a non-profit online counselling web portal that was built to provide a platform for counselors to reach out to the general public. We examine the background that induced the conceptualization of the portal, the system’s architecture and design as well as the implementation of the working system. The paper closes with an evaluation of the system. Counselling aim is to help a person to talk about emotions and thoughts that they may not have been able to express before, or address important matters they have put off, which always seems to return. Islam tells its followers to attain personal well-being through its system of spiritual and religiosity. This paper explore on how to council process of face boldly between professional counselors with client for make human affair, to identify self-potential and develop source of human internal for take as true and self-responsible toward Allah bless

Mixed convection boundary layer flow along vertical moving thin needles with variable heat flux

The problem of steady laminar mixed convection boundary layer flow of an incompressible viscous fluid along vertical moving thin needles with variable heat flux for both assisting and opposing flow cases is theoretically considered in this paper. The governing boundary layer equations are first transformed into non-dimensional forms. The curvature effects are incorporated into the analysis whereas the pressure variation in the axial direction has been neglected. These equations are then transformed into similarity equations using the similarity variables, which are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The solutions are obtained for a blunt-nosed needle (m = 0). Numerical calculations are carried out for various values of the dimensionless parameters of the problem, which include the mixed convection parameter λ, the Prandtl number Pr and the parameter a representing the needle size. It is shown from the numerical results that the skin friction coefficient, the surface (wall) temperature and the velocity and temperature profiles are significantly influenced by these parameters. The results are presented in graphical form and are discussed in detail

Free Convection Boundary Layer Flow Over Cylinders of Elliptic Cross Section with Constant Surface Heat Flux

The steady laminar free convection boundary layer flow over horizontal cylinders of elliptic cross section when the major axis is both horizontal (blunt elliptic cylinder) and vertical (slender elliptic cylinder) subjected to a constant surface heat flux placed in an incompressible viscous fluid is considered in this paper. The governing boundary layer equations are solved numerically using the Keller box method. The numerical solutions are obtained for various values of the Prandtl number and parameter b/a (the ratio of the major and minor axes of the cylinder) for both blunt and slender orientations

The effect of conducting sidewalls on the onset of convection in a porous cavity

Abstract In this short paper we consider the effect of the presence of conducting sidewalls of finite thickness on the onset of convection in a two-dimensional porous cavity. Two cases are considered where the outer boundaries of the sidewalls are either perfectly insulating or perfectly conducting. A unified theory is presented which combines both these cases, and the stability properties of the overall system is found to undergo a full transition from that of the classical Darcy-Bénard problem to that of the degenerate system studied in detail by Rees and Tyvand (2004)

Unsteady Separated Stagnation-Point Flow with Suction towards a Stretching Sheet

The problem of unsteady boundary layer separated stagnation-point flow towards a porous stretching sheet is considered. By using a similarity transformation, the governing equations are reduced to a system of ordinary differential equations which are then solved numerically. The effects of suction and stretching parameters on the flow characteristics are studied. It is observed that the solutions admit two types of solutions, one is the attached flow solution and the other is reverse flow solution

Bödewadt flow and heat transfer in nanofluid over a permeable and radially stretching disk

A Bödewadt boundary layer flow and heat transfer problem in nanofluid was investigated in this study for suction/injection as well as combined effects of suction/injection and radial stretching disk. Similarity variables were introduced to transform the three-dimensional flow into a system of ordinary differential equations. Moreover, similar to the Bödewadt heat transfer problem in a viscous fluid, adequate suction is also required so that similarity solutions exist for nanofluid problems with no other boundary effects such as a partial slip or stretching disk. Both the suction and stretching disk effects can suppress the natural oscillatory behavior of flow apart from reducing the momentum and thermal boundary layer thicknesses. As expected, injection acts oppositely. However, the skin friction coefficient and heat transfer rate for Bödewadt flow increase with the increasing suction and stretching parameters. As for stagnant disk, increasing the nanoparticle volume fraction can enhance the wall shear stress, whereas nanofluid can only enhance the heat transfer when both the suction and nanoparticle volume fraction are sufficiently small. For radially stretching disk, both the local skin friction coefficient and local Nusselt number increase as the nanoparticle volume fraction increases. However, for larger suction, a smaller volume fraction of nanoparticles yielded enhanced heat transfer than the larger volume fraction of nanoparticles

Criminalising lesbian sexual conducts in Malaysia / Nur Ilmi Syakila Mazalan … [et al.]

The purpose of the research paper is to address the issue of lesbian sexual conducts that has become prevalent in Malaysia nowadays. This research is important since it is aimed to fill in the lacuna in our local law in regulating the lesbian sexual conduct in Malaysia. It is also aimed to reduce the issues of lesbianism in our country. Our main argument is that, since there is no law to regulate the lesbian sexual conducts in our Civil Penal Code (Act 574), the issue such as discrimination will arise since the Syariah law criminalise lesbianism between Muslims women, but no such law exist in our Penal Code to criminalise the issue at hand. This research paper is accomplished by several methods, which consisted of an interview with a Syariah lawyer and a questionnaire that was distributed to 100 students in the Faculty of Law UiTM Shah Alam. From the research itself, we found that people do aware of the existence of lesbianism in the country and most of the respondents to the questionnaire that we had distributed do agree that necessary amendment to the Penal Code should be made to the Penal Code in order to have one civil law to regulate the lesbians sexual conduct. Therefore, the abovementioned argument is supported by the findings of the research itself