Comments on “Viscous-dissipation effects on the heat transfer in a Poiseuille flow” by O. Aydin and M. Avci

This note comments on an article by Aydin and Avci [1]; the paper treats the same problem as that studied analytically by Ou and Cheng [2] and numerically by Hwang et al. [3], namely the effects of viscous- dissipation on forced convection in a parallel plate channel

Analysis of heat transfer and entropy generation for a thermally developing Brinkman–Brinkman forced convection problem in a rectangular duct with isoflux walls

Heat transfer and entropy generation analysis of the thermally developing forced convection in a porous-saturated duct of rectangular cross-section, with walls maintained at a constant and uniform heat flux, is investigated based on the Brinkman flow model. The classical Galerkin method is used to obtain the fully developed velocity distribution. To solve the thermal energy equation, with the effects of viscous dissipation being included, the Extended Weighted Residuals Method (EWRM) is applied. The local (three dimensional) temperature field is solved by utilizing the Green’s function solution based on the EWRM where symbolic algebra is being used for convenience in presentation. Following the computation of the temperature field, expressions are presented for the local Nusselt number and the bulk temperature as a function of the dimensionless longitudinal coordinate, the aspect ratio, the Darcy number, the viscosity ratio, and the Brinkman number. With the velocity and temperature field being determined, the Second Law (of Thermodynamics) aspect of the problem is also investigated. Approximate closed form solutions are also presented for two limiting cases of MDa values. It is observed that decreasing the aspect ratio and MDa values increases the entropy generation rate

An Eye-Opening Experience with Visual Impairment Students’ environment in Brunei Darussalam

This paper aims to explore the experiences of students with visual impairment (VI) within their built school environment. A qualitative case study of four students with VI from three secondary government schools were interviewed following site observations of their schools. The study found that the students with VI do face anxiety towards their built school environment alongside the barriers they faced which can be thematically categorized into physical barriers, auditory barriers and lighting barriers. The study also revealed that many aspects of the school buildings and environment presented challenges and are intimidating to maneuver for VI students. The study has implications in expanding the field of study into Universal Design within Brunei Darussalam where future research can approach UD and it’s aspects in depth. Finally, the country had started dialogue regarding accessibility and its significance in the country’s National Vision Plan 2035 and the study hopes to bring insight into the types of barriers the built environment can have on students with VI and signal future development projects forward

Slip flow forced convection in a microporous duct of rectangular cross-section

Applying a Fourier series approach, closed form solutions for fully developed velocity and temperature distribution in a porous-saturated microduct of rectangular cross-section are presented in the slip-flow regime. The Brinkman flow model is applied. Invoking the temperature jump equation, the H1 thermal boundary condition is investigated. Expressions are presented for the local and average velocity and temperature profiles, the friction factor, and the slip coefficient in terms of the key parameters. The present results, which are applicable to microducts of rectangular cross-section filled with or without a porous medium, are found to be in complete agreement with those available in the literature for both no-slip and slip flow regime

A comprehensive review of vehicle detection using computer vision

A crucial step in designing intelligent transport systems (ITS) is vehicle detection. The challenges of vehicle detection in urban roads arise because of camera position, background variations, occlusion, multiple foreground objects as well as vehicle pose. The current study provides a synopsis of state-of-the-art vehicle detection techniques, which are categorized according to motion and appearance-based techniques starting with frame differencing and background subtraction until feature extraction, a more complicated model in comparison. The advantages and disadvantages among the techniques are also highlighted with a conclusion as to the most accurate one for vehicle detection

Conduction in rectangular plates with boundary temperatures specified

Steady-state components of heat conduction solutions may have very slowly convergent series for temperatures and non-convergent heat fluxes for temperature boundary conditions. Previous papers have proposed methods to remove these convergence problems. However, even more effective procedures based on insights of Morse and Feshbach are given herein. In some cases it is possible to replace poorly-convergent or non-convergent series by closed-form algebraic solutions. Examples are given

Effects of temperature-dependent viscosity variation on entropy generation, heat and fluid flow through a porous-saturated duct of rectangular cross-section

Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the H boundary condition in the terminology of Kays and Crawford, is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. Having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio (width to height ratio). These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case