Thermal radiation effects on heat and mass transfer of magnetohydrodynamics Dusty Jeffrey fluid past an exponentially stretching sheet

The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow be- haviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concen- tration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in ra- diation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration

Stagnation point flow of MHD dusty fluid toward stretching sheet with convective surface

This paper presents the study of stagnation point of hydromagnetic flow of dusty fluid over a stretching sheet with the bottom surface of sheet heated by convection from hot fluid. The governing partial differential equations are transformed into a system of nonlinear ordinary differential equations using similarity transformation. These resulting nonlinear ordinary differential equations are solved numerically by using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The characteristics of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid are analyzed and discussed for different parameters of interest such as convective Biot number, fluid-particle interaction parameter, magnetic parameter, ratio of free stream velocity parameter and Prandtl number on the flow. The numerical results are compared with previous published results for validation

Hydromagnetic boundary layer flow of a dusty fluid in a porous medium over a stretching sheet with slip effect

This paper investigated the problem of hydromagnetic boundary layer flow and heat transfer of a dusty fluid over a stretching sheet through a porous medium. The velocity slip was considered instead of the no-slip condition at the boundary. The governing partial equations were reduced into a set of non-linear ordinary differential equations by using the suitable similarity transformation. The transformed equations were numerically integrated using bvp4c in Matlab. The effects of various physical parameters on the velocity and temperature profiles of both phases, such as fluid-particle interaction parameter, magnetic parameter, mass concentration parameter, porosity parameter and Prandtl number were obtained and analyzed through several plots. Useful discussions were carried out with the help of plotted graphs and tables. Under the limiting cases, the obtained numerical results werecompared and found to be in good agreement with previously published results

Collision of hybrid nanomaterials in an upper-convected Maxwell nanofluid: A theoretical approach

Many viscoelastic fluid problems are solved using the notion of fractional derivative. However, most researchers paid little attention to the effects of nonlinear convective in fluid flow models with time-fractional derivatives and were mainly interested in solving linear problems. Furthermore, the nonlinear fluid models with a fractional derivative for an unsteady state are rare, and these constraints must be overcome. On the other hand, nanofluids are thought to be trustworthy coolants for enhancing the cool¬ing process in an electrical power system. Therefore, this research has been conducted to analyze the unsteady upper-convected Maxwell (UCM) hybrid nanofluid model with a time-fractional derivative. Incorporating the Cattaneo heat flux into the energy equation has increased the uniqueness of the research. The numerical solutions for the coupled partial differential equations describing velocity and temperature are presented using an efficient finite difference method assisted by the Caputo fractional derivative. Significant changes in heat transfer and fluid flow properties due to governing parameters, including the nanomaterial volume fraction, fractional derivative, relaxation time, and viscous dissipa¬tion, are graphically demonstrated. The nanomaterial concentration, the fractional derivative parameter, and the relaxation time parameter must all be substantial to manifest a surface heat increase

Quadratic convective nanofluid flow at a three-dimensional stagnation point with the g-jitter effect

The nonlinear density variation with temperature happens in many thermal applications like solar collectors, energy production, heat exchangers, and combustions, and it gives a significant impact on heat transfer and fluid flows. Thus, a nonlinear convective of an unsteady stagnation point flow under the influence of gravity modulation in the presence of water-based nanoparticles alumina (Al2O3) is studied here. Suitable variables are utilized to reduce the highly coupled nonlinear governing equations into a system of dimensionless simple partial differential equations. The Keller-box method is then applied to solve the consequent governing equations. Velocity and temperature profiles for various values of pertinent parameters are displayed graphically and discussed. The results indicate that the quadratic convection has enhanced the fluid flow and heat transport. Furthermore, the nonlinear convection parameter and the nanoparticles volume fractions have delivered a positive effect on the skin friction and the rate of heat transfer

Efforts to Improve PBI/Acid Membrane System for High Temperature Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC)

The global expansion of industry and technology has brought various environmental issues especially in atmospheric pollution and global warming. These resulted in various R&D activities on renewable energy resources and devices. Developing high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) is one of them. Over the past decades, this research has been received the most attention for various stationary and transportation applications. This is due to inherent advantages of operation above 100 °C including improved tolerance toward CO poisoning, enhanced electrode kinetics, easier heat dissipation and water management as well as better thermodynamic quality of the produced heat. Poly (benzimidazoles)-phosphoric acid (PBI/PA) is the well-established membrane for HT-PEMFC applications replacing perfluorinated sulfonic acid (PFSA) membranes, which operate in the temperature range of below 100 °C. Nevertheless, there have been concerns on the durability and stability of such PEMFC, which negatively affected their widespread commercialization. In this paper, problems regarding this acid-base complex membrane system and modifications as well as some techniques used to overcome these issues will be outlined

Biochemical composition of freshwater mussels in Malaysia: a neglected nutrient source for rural communities

Nutrient deficiency is still prevalent in Southeast Asia. Freshwater mussels (Unionida) are widespread and consumed by low-income, rural and indigenous communities, but their biochemistry is poorly known. We assessed concentrations of nutrients and harmful heavy metals in Malaysian freshwater mussels. Three replicate batches of 5–10 specimens of native Pilsbryoconcha compressa and non-native Sinanodonta woodiana were collected from one and three habitats, respectively, i.e. a rice paddy channel (both species), a lake and an abandoned mining pool (only S. woodiana). Macro- and micronutrient concentrations were determined on freeze-dried, ground mussel meat powder using established methods, including inductively coupled plasma mass spectrometry and direct mercury analyser. Concentrations differed significantly between and within species, but all populations were excellent sources of essential micronutrients. A serving of six mussels on average covered >100% of the recommended daily intake for adults of chromium, iron and manganese, and about 40–60% of calcium, copper, selenium and zinc. However, three of the four populations exceeded permissible levels of some heavy metals, especially arsenic and lead. Protein levels were low with 5–9 g 100 g−1 wet weight. Freshwater mussels may therefore represent an important nutrient source for rural, low-income communities, but should not be eaten in large quantities

Unsteady micropolar boundary layer flow and convective heat transfer

Most industrial fluids such as polymers, liquid crystals and colloids contain suspensions of rigid particles that undergo rotation. However, the classical Navier- Stokes theory normally associated with Newtonian fluids is inadequate to describe such fluids as it does not take into account the effects of these microstructures. In this research, the unsteady boundary layer forced and mixed convection of micropolar fluids are considered where the unsteadiness is due to an impulsive motion of the free stream. Both small and large time solutions as well as the occurrence of flow separation, followed by flow reversal are taken into account. The two-dimensional flow along the entire surface of a cylinder and a sphere is solved numerically using the Keller’s box scheme in a three dimensional grid where the discretization is made either on a net cube, or a zig-zag grid in the case of flow reversal. The numerical results show that as the micropolar material parameter increases, the thickness of both velocity and microrotation boundary layers, as well as the peak value of the skin friction coefficient along the body surface, also increase. Meanwhile, the value of the Nusselt number, in the case of micropolar fluids, is lower near the forward stagnation point and higher near the rear stagnation point compared to Newtonian fluids. It is also found that the separation time is brought forward in both cases of weak and strong concentration of microelements in the assisting mixed convective flows. However, in the opposing case, the separation time is delayed for a flow past a cylinder, while for a flow past a sphere, only the weak concentration of microelements can give similar results

Unsteady mixed convection flow over a cylinder of elliptic cross section near forward stagnation point

The unsteady mixed convection flow over a cylinder of elliptic cross section when the major axis is horizontal (blunt orientation) or vertical (slender orientation) near forward stagnation point is studied. The unsteadiness is due to an impulsive motion on the free stream. The governing boundary layer equations are first reduced into a non-dimensional form, and then transformed into a set of non-similar boundary layer equations, which are solved numerically using an efficient implicit finite-difference method known as Keller-Box method. The numerical results are obtained for various values of the Prandtl number, Pr, the mixed convection parameter, α and parameter for blunt and slender orientation, ω. The effects of these parameters on velocity profiles,temperature profiles as well as Nusselt number are presented through graphs and tables. The results show that as the mixed convection parameter, α is increased, the velocity of the fluid is increased but the temperature of the fluid is decreased, for both blunt and slender orientations. Furthermore, the slender orientation gives earlier separation times for opposing flow while there is no separation of flow detected for the assisting flow