AHaake viscometer was used for viscosity measurements of aqueous polyvinyl alcohol mixtures at temperatures of 288, 298, and 308 K. It was observed that at low concentration of polyvinyl alcohol, variations of the measured shear stress (τ) versus shear rate (γ) were linear and therefore, the Newtonian behaviour of the studied mixtures is considered. The modified Eyring viscosity model previously proposed by the authors was used to test the measured data for aqueous polyvinyl alcohol mixtures. It was shown that the model is well capable to fit the data and the parameters, of the modle are evaluated.

Oils of vegetable origin are of great importance in food, soap, and cosmetic industries which are sometimes used as lubricants and raw materials for biodiesel production depending on their viscosity and thermal stability. This work provides insight into the fatty acid components, physicochemical properties and thermal stability of some refined vegetable oils. The Saponification values, peroxide values, acid values, iodine values and refractive index of these oils range from 185. 38 to 209. 26 mg g-1 KOH, 2. 00 to 37. 00 meq O2/kg, 2. 50 to 5. 50 mg KOH/g, 31. 09 to 89. 46 g/100g and 1. 441 to 1. 488, respectively The activation energies obtained from Arrhenius-type equation vary from 11. 32 to 3. 85 kJ mol-1, while the enthalpy (Δ H#) and entropy (Δ S#) of activation obtained from Eyring-type equation range from 6. 852 to 14. 317 kJ mol-1 and-31. 85 to-29. 06 J mol-1 K-1, respectively. The Gibbs free energy of activation (Δ G#) ranges from 15. 51 to 23. 81 kJ mol-1. The Pw oil brand has the highest thermal stability and resistance to shear stress due to its high activation energy and a low degree of unsaturation. The heat was absorbed during the process, the reaction mechanism was associative and the entire process was nonspontaneous.

The current article has investigated unsteady convective flow for MHD non-Newtonian Powell-Eyring fluid embedded porous medium over inclined permeable stretching sheet. We have pondered the thermophoresis parameter, chemical reaction, variable thermal conductivity, Brownian motion, variable heat source and variable thermal radiation in temperature and concentration profiles. Using similar transformation, the PDEs are converted by couple ODEs and solve by R– K– Fehlberg 4th– 5th order method. The physical features of nondimensional radiation parameter, non-Newtonian fluid parameters, suction /injection parameter, mass Grashof number porosity parameter, temperature ratio parameter, thermal Grashof number, Biot number of temperature and Biot number of concentration have been analyzed by plotting the graphs of graphical representations of momentum, heat, and mass profiles. Cf Re 1/2, Nu Re x-1/2 and Sh Re x-1/2 have been analyzed. The transfer rate of temperature is decreased whereas the flow rate offluid grows with an enhancement in (K) and (Gr). The transfer rate of the temperature is distinctly boosted whereas the fluid flow rate is distinctly declined with an enhancement in (M), (Kp).

Heat and mass transfer effects in three-dimensional mixed convection flow of Eyring Powell fluid over an exponentially stretching surface with convective boundary conditions are inspected. Cattaneo-Christov Heat Flux model is a modified version of the classical Fourier's law that takes into account the interesting aspect of thermal relaxation time. First-order chemical reaction effects are also taken into account. Similarity transformations are invoked to reduce the leading boundary layer partial differential equations into the ordinary differential equations. The nonlinear, coupled ordinary differential with boundary conditions has been analyzed numerically by using the Finite Element Method.

This article investigates the controlling effects of electromagnetic field generated by Riga plate on the boundary layer flow of non-Newtonian fluid. Two classical viscosity models of non-Newtonian fluids namely; Powell-Eyring and Reiner-Phillipoff fluid models have been considered to study the different behaviors of non-Newtonian fluid flow. Numerical solution of the problem in the presence of strong suction is obtained using the nonlinear shooting method. The results are studied in terms of modified Hartmann number, non-Newtonian fluid parameters and the Bingham number. Linear regression is performed on the numerical results to present the correlation expression for the skin friction.

The problem of convective heat transfers of Eyring-Powell conveying Copper (Cu) coupled with alumina (Al2O3) are employed as the combination of particles, along with water as the base fluid over a vertical Riga plate is numerically addressed. The performance of heat transmission is influenced by the electromagnetohydrodynamic (EMHD) imposed produced from the Riga plate, and it could be used to postpone boundary layer separation. A model in the form of Partial Differential Equations (PDEs) is introduced to describe the physical behavior of the proposed problem. With the inclusion of relevant equation variables, this collection of PDEs is transformed into Ordinary Differential Equations (ODEs) which are in a less complex form. Then the bvp4c solver was employed to solve the respective equations. The characteristics of fluid velocity and temperature are investigated graphically. It is found the buoyancy assisting and opposing flows offered dual solutions whereas the purely forced convection flow gives a unique solution. Through an investigation of flow stability, the first solution is confirmed as the physical one. In essence, the volumetric concentration of Cu increases the heat-transferring ability for assisting and opposing flows. The higher suction imposed at the boundary causes a decrease in the heat transfer rate under the shrinking case.