Narrow Results

Axisymmetric flow is of both fundamental interest and practical significance. A recently derived axisymmetric lattice Boltzmann model [J. G. Zhou, Phys. Rev. E78, 036701 (2008)] is adopted for studying several typical axisymmetric flows. First, the Hagen–Poiseuille flow in circular pipes is validated and the Poiseuille flow in annular cylinders is studied under different values of the radius ratio. Second, pulsatile flow in an axisymmetric pipe with a sinusoidal pressure gradient is conducted. Third, flows through pipes with various constrictions or expansions are discussed. Finally, we extend the axisymmetric lattice Boltzmann method for non-Newtonian flow. It is found that the obtained numerical results agree well with available analytical solutions. It is also observed that constriction or expansion in a pipe influences the velocity distribution of the flow significantly. In addition, the results demonstrate that the modified axisymmetric lattice Boltzmann model is capable of handling non-Newtonian flow.

General slip boundary condition is used to solve the viscous incompressible flows induced by a stretching sheet. These flow problems corresponds to the planar and axisymmetric stretching. A similarity solution is developed by shooting method using Runge–Kutta algorithm. The results are graphically displayed and discussed under the influence of slip parameter and critical shear rate. The comparison of stretching flow problem subject to Navier's boundary condition in the planar case is made with the available numerical results in the literature.

Hybrid nanofluid is deployed to optimize the heat transfer features of an axisymmetric magnetohydrodynamic (MHD) flow exterior to a rotating cylinder. Hybrid nanofluids contain composite nanoparticles, which improve thermal conductivity. Here, two distinct particles single and multi-walled carbon nanotubes (CNTs) are taken and mixed to form hybrid nanoparticles, and water is taken as the working fluid. The energy transport phenomenon is examined by incorporating the Joule heating effect. The axial pressure gradient is generated as a consequence of the torsional motion of the cylinder, which results in the wall jet phenomenon on the axial axis. The governing equations are transformed into an ordinary differential system in view of the similarity group. The numerical approach bvp4c is employed to solve the problem. The graphical results for flow and thermal energy transport with a comparison of nanofluid and hybrid nanofluid are analyzed. The axial component of velocity escalates by augmenting Reynolds number, while the azimuthal components of velocity and thermal profile decline. Moreover, the numerical outcomes of wall stresses and Nusselt number enhance for higher Reynolds number. The temperature field declines by increasing the Prandtl number because of less thermal diffusivity.

Nowadays, the heat thrust liquid electric heater is generally used in profitable applications since it protects upto 2–3 times the energy of ordinary liquid electric heater. The heat pump makes use of a refrigerant for its process. The small-temperature refrigerant engrosses permitted heat from full of atmosphere midair in the evaporator which is crushed by an extremely well-organized electrical compressor to an extraordinary-temperature and high-pressure vapor refrigerant. For entire heat transfer connoisseurs, heat transfer performance in cooling and heating applications has become a top priority. Hence, research towards new heat transfer fluids is extremely intense and challenging. This investigation examines flow and heat transfer analysis in axisymmetric magnetohydrodynamic flow polyethylene glycol (PEG)-based nanofluid, hybrid nanofluid and ternary hybrid nanofluid flow induced by a swirling cylinder. Flow and heat transfer are analyzed and compared for three cases PEG-based copper oxide, magnesium oxide and zirconium oxide ternary nanofluid (PEG$+$ZrO₂$+$CuO$+$MgO), PEG-based copper oxide (PEG$+$CuO) nanoparticles and PEG-based zirconium and magnesium oxide hybrid nanofluid (PEG$+$ZrO₂$+$MgO). Shooting technique (R–K fourth-order) is employed to work out the flow equations numerically. Simulated results are displayed through graphs. The computational results are validated with the published research work and a modest concurrence is found. The main outcome of this study is found to be as follows: It is interesting to note that $C_{fx}\mathrm{\text{Re}}(\frac{x}{R})$ is lesser in nanofluid case compared with ternary and hybrid nanofluid cases. It is found that $C_{f\varphi }\mathrm{\text{Re}}(\frac{G}{HR})$ is more in ternary hybrid nanofluid compared with hybrid and nanofluid cases. Overall, it is observed that heat transfer rate is higher in nanofluid compared with ternary and hybrid nanofluid cases whereas lesser rate of heat transfers in ternary nanofluid case.

Over the last 10 years, heat transfer performance in immediate cooling and heating applications has grown into the foremost concern for heat transfer practitioners in Engineering and manufacturing practices. Henceforward, the study in new heat transfer fluids is extremely intense and challenging. This study examines flow and thermal management in axisymmetric hydrodynamic pure water-based hybrid solid nanoparticles in a flow induced by a swirling cylinder with Fourier Heat source. Flow and heat transfer are analyzed and compared for ${\text{CNT+Graphene+Al}}_2{\mathrm{\text{O}}}_3$ and Paraffin wax+Sand+AA7072 hybrid nanofluid flow. Shooting technique (R-K 4th order) is applied to work out the flow equations numerically. Simulated results are exhibited through graphs and tables. The computational results are statistically validated with the published research work and a modest concurrence is found. The main outcome of this study is found to be in Multi-regression analysis, where the $\mathrm{\Lambda }$ w.r.t $Pr$ has higher domination compared to $\mathrm{\Phi }$ w.r.t $Pr$. Also, it is interesting to know that $\mathrm{\Phi }$ w.r.t Re has more rate of heat transfer compared to $\mathrm{\Phi }$ w.r.t $M$. As the volume fraction rises, the size of the particle is less and Reynolds number dominated the flow, due to this, a decrement is seen in the friction values. Overall, it is observed that heat transfer rate is higher in CNT+Graphene+Al₂O₃ compared with Paraffin wax+Sand+AA7072.

Engineers and researchers in the field of heat transfer are in search of new techniques to optimize the performance of energy devices through heat transfer enhancement. For that reason, the flow analysis involving nanoparticles is assumed to be one of the most important techniques for enhancing heat transfer systems. Being a two-component system, different numerical approaches are available to model the thermo-fluids behavior of nanofluids. The current study describes the investigation of Buongiorno model for evaluation of transient flow and heat transfer of Williamson nanofluids under the impacts of velocity slip and magnetic field. In addition, the effects of heat generation/absorption and convective heat transfer have been employed in this analysis. The Boussinesq-approximations are implemented to obtain the governing conservation equations for nanofluids transport phenomenon. The leading equations of the modeled physical problem have been solved using a MATLAB code, based on Nachtsheim–Swigert shooting iteration scheme. The novelty of the current investigation is the existence of multiple solutions for the nanofluids flow past a radially shrinking surface by considering the effects of uniform suction at the wall. In this review, it is seen that the investigated physical parameters affect remarkably on the nanofluid stream function, temperature and nanoparticles concentration. The skin friction, local Nusselt number and the local Sherwood number and some samples of velocity, temperature and nanoparticle concentration profiles are discussed and presented with the help of graphs. From this study, it is observed that the existence range of dual solutions is significantly raised by the higher Weissenberg number.