This study reports on combined thermal radiation, chemical reaction, and magnetic field effects on entropy generation in an unsteady nanofluid flow past an inclined cylinder using the Buongiorno model. We consider the impact of viscous dissipation, velocity slip conditions, thermal slip conditions, and the Brownian motion. The transport equations governing the flow are solved using an overlapping grid spectral collocation method. The results indicate that entropy generation is suppressed significantly by thermal radiation and chemical reaction parameters but enhanced with the magnetic field, viscous dissipation, the Brinkman number, and the Reynolds number. Also, fluid flow variables are affected by the thermophoresis parameter, the angle of cylinder inclination, and the Richardson number. We present the findings of the skin friction coefficient, the Nusselt number, and the Sherwood number. The model is applicable in fields such as the petroleum industry, building industries, and medicine.

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This study investigates entropy generation due to the unsteady boundary layer flow of an Oldroyd-B nanofluid past a Riga plate. The velocity, temperature and concentration fields are obtained and the flow equations solved numerically using the spectral collocation method with overlapping grids. The local entropy generation distribution is obtained by solving the entropy generation equation numerically. Sensitivity and convergence analysis is performed to demonstrate the accuracy and convergence of the numerical method. The effect of principal flow parameters on entropy generation is investigated and it is established that entropy generation is directly proportional to the width of the Riga plate, Brinkman number, Prantl number and the Brownian motion parameter. It is further shown that the entropy generation is inversely proportional to the Eckert number and Deborah number in relaxation time. The range of parameter values were obtained from the reported literature. The current study may have applications of physics, including in the design of both cooling and heating devices.

Background: This study investigates an unsteady, two dimensional, incompressible viscous boundary layer flow of an electrically conducting nanofluid past parallel plates. The plates are permeable to allow both suction and injection to take place. It is assumed that viscosity, thermal conductivity and mass diffusivity of the nanofluid vary with temperature. The novelty of this study is in the consideration of the combined effects of chemical reaction, permeability, externally applied magnetic field and momentum diffusivity on the flow varibles. The magnetic field force is significant because it provides information about the boundary layer characteristics. Methods: The highly nonlinear partial differential equations are solved numrically using the newly developed bivariate spectral quasilinearization method (BSQLM) along with varying thermal and concentration boundary conditions. The BSQLM method is an innovative technique that is more reliable and robust as it demands for fewer grid points and has a global approach of solving PDEs. Results: An analysis and comparison of results with existing literature is reported. Excellent agreement is found between our results and those previously published. Among the findings, we show, inter alia, a significant increase in the profiles for fluid velocity, temperature and concentration with an increase in the chemical reaction, applied magnetic field, and thermal radiation. The BSQLM converges fast and is computationally efficient when applied to boundary layer problems that are defined on a large computational domain. Conclusions: A numerical study on nanofluid flow between parallel porous plate is carried out and here are key findings:

We numerically investigate mixed convective heat and mass transport in incompressible nanofluid flow through an exponentially stretching sheet with temperature-dependent viscosity. The fluid flow equations are transformed to a system of non-linear ordinary differential equations using appropriate similarity transformations and solved numerically by using the multi-domain bivariate spectral quasi-linearization technique. The fast convergence of the method is shown by demonstrating that the error is exponentially small for a finite number of iterations. The significance and impact of different fluid parameters are presented and explained. For engineering relevance, the entropy generation number has been calculated for different fluid parameter values.