Non-axisymmetric Homann stagnation-point flow of unsteady Walter's B nanofluid over a vertical cylindrical disk

Particular non-axisymmetric Homann stagnation point flow of Walter’s B fluid over a vertical cylindrical disk is considered in this work. Important physical aspects of newly transient state problem are described by incorporating the effects of magnetic field and mixed convection. Additionally, the temperature and solute concentration are expressed with new parameters in the form of Brownian motion, thermophoretic force, thermal radiation, and 1st order chemical reaction. Furthermore, the problem is modeled with non-linear PDE’s, and which are further converted into ODE’s along with the proposed geometric conditions. Exploration of new physical impacts are described in the form of velocity, temperature, concentration, and displacement thicknesses by applying numerical scheme. However, the momentum equation subjected to the insufficient boundary conditions converting us to apply perturbation technique to reduce the order of ODE accordingly. It is conducted that displacement thicknesses [Formula: see text] and [Formula: see text] tends to its asymptotic value, as [Formula: see text] On the other hand, the displacement thickness [Formula: see text] is found in reverse trends, for the same escalating values of viscoelastic parameter. The skin friction [Formula: see text] variation against viscoelastic parameter is noticed with uplifting trend when [Formula: see text] and vice versa, for [Formula: see text] Outcomes for the Nusselt and Sherwood numbers and rate of heat and mass transfer have been obtained and discussed for parametric variations of the buoyancy parameter ξ, magnetic parameter M, temperature ratio parameter, Brownian motion parameter [Formula: see text], thermophoresis parameter [Formula: see text] and 1st order chemical reaction Rc. Also, shows relative growth for the momentum and concentration profiles.

Off-centered stagnation point flow of an experimental-based hybrid nanofluid impinging to a spinning disk with low to high non-alignments

Purpose The purpose of this study is to model and solve numerically the three-dimensional off-centered stagnation point flow and heat transfer of magnesium oxide–silver/water hybrid nanofluid impinging to a spinning disk. Design/methodology/approach The applied effective thermophysical properties of hybrid nanofluid including thermal conductivity and dynamics viscosity are according to the reported experimental relations that would be expanded by a mass-based algorithm. The single phase formulations coupled with experimental-based hybrid nanofluid model is implemented to derive the governing partial differential equations which are then transferred to a set of dimensionless ordinary differential equations (ODEs) with the use of the similarity transformation method. Afterward, the reduced ODEs are solved numerically by bvp4c function from MATLAB that is a trustworthy and efficient code according to three-stage Lobatto IIIa formula. Findings The effect of spinning parameter and nanoparticles masses (mMgO, mAg) on the hydrodynamics and thermal boundary layers behavior and also the quantities of engineering interest are presented in tabular and graphical forms. The recent work demonstrates that the analysis of flow and heat transfer becomes more complicated when there is a non-alignment between the impinging flow and the disk axes. From computational results demonstrate that, the radial and azimuthal velocities are, respectively, the increasing and decreasing functions of the disk spinning parameter. Further, for the greater values of the spinning parameter, an overshoot of the radial velocity owing to the centrifugal forces of the spinning disk is observed. Besides, the quantities of engineering interest gently enhance with first and second nanoparticle masses, while comparing their absolute values illustrates the fact that the effect of second nanoparticle mass (mAg) is greater. Further, it is inferred that the second nanoparticle’s mass enhancement results in the amplification of the heat transfer; although, the high skin friction and the relevant shear stress should be controlled. Originality/value The combination of experimental thermophysical properties with theoretical modeling of the problem can be the novelty of the present work. It is evident that the experimental relations of effective thermophysical properties can be trustable and flexible in the theoretical/mathematical modeling of hybrid nanofluids flows. Besides, to the best of the authors’ knowledge, no one has ever attempted to study the present problem through a mass-based model for hybrid nanofluid.

Impact of nanoparticle shape on magnetohydrodynamic stagnation-point flow of Carreau nanoliquid: A comparative study

In this paper, a numerical computational work is carried out to investigate the significance of nanoparticle shape on magnetohydrodynamic stagnation-point flow of Carreau nanoliquid caused by a horizontally moving thin needle. The drive and thermal transport nature of Ti6Al4V+Ethylene glycol nanoliquid under the stimulus of space-dependent heat source and magnetized force is discussed numerically. The novelty of this work is to obtain the simultaneous solutions for three different shapes of nanoparticles namely spherical, cylindrical and laminar. The flow governing partial differential equations are transformed into ordinary differential equations with appropriate similarity variables and solved numerically by using Runge–Kutta and Newton's approach. Numerical outcomes of velocity and thermal distributions under the influence of different physical parameters are illustrated via graphical trends, wall friction and rate of heat transfer are interpreted using tabular values. It reveals from results that the thermal transfer performance of the Carreau nanoliquid is advanced when spherical shaped nanoparticles are used as compared with cylindrical and laminar-shaped nanoparticles. Also, it is witnessed that needle thickness parameter plays vital role in augmenting thermal transport rate of the nanoliquid.

Radiation effect on three-dimensional stagnation point flow involving copper-aqueous titania hybrid nanofluid induced by a non-Fourier heat flux over a horizontal plane surface

This research numerically investigates 3D stagnation-point flow (SPF) past a horizontal plane surface conveying copper-aqueous titania hybrid nanofluid induced by non-Fourier heat flux (NFHF) that utilized in heat transfer processes. A Tiwari-Das model is engaged to examine the fluid flow dynamics and the heat transfer features of the hybrid nanofluid with thermal radiation effect. With aid of similarity variables, the leading nonlinear system involving partial differential equations (PDEs) is reduced to a system of ordinary differential equations (ODEs). This set of dimensionless coupled ODEs is then tackled through the bvp4c solver in MATLAB. For hybrid nanofluid, the graphical findings of the pertaining parameters as well as the saddle/nodal indicative parameter are disclosed and explained with the assist of figures and tables. The results illustrate that the rise of hybrid nanoparticles declines the motion of the fluids in both axes of coordinates ( and directions), while the temperature enhances. In addition, the temperature distribution declines due to relaxation parameter but uplifts due to radiation. Also, the thermal relaxation parameter reduces the temperature. Moreover, the present solution displays an excellent agreement with earlier published works in the limited cases of normal fluid and nanofluid.

Unsteady stagnation point flow past a permeable stretching/shrinking Riga plate in Al2O3-Cu/H2O hybrid nanofluid with thermal radiation

Purpose The investigation of fluid flow and heat transfer is incredibly significant in the present era, particularly in the engineering and manufacturing industries. Hence, this study aims to concern with analysing the unsteady stagnation point flow towards a permeable stretching/shrinking Riga plate of Al2O3-Cu/H2O. The effect of thermal radiation on the boundary layer flow is also taken into account. Design/methodology/approach The multi-variable differential equations with partial derivatives are transformed into third-order and second-order differential equations by applying appropriate transformations. The reduced mathematical model is solved in the MATLAB system by using the bvp4c procedure. This solution approach is capable of producing multiple solutions once the necessary assumptions are provided. Findings The results of various control parameters were analysed, and it has been observed that raising the solution viscosity from 0% to 0.5% and 1% improves the coefficient of skin friction and thermal conductivity by almost 1.0% and 1.9%. Similar response and observation can be witnessed in the addition of modified Hartmann number where the highest values dominate about 10.7% improvement. There is a substantial enhancement in the heat transfer rate, approximately 1.8% when the unsteadiness parameter leads around 30% in the boundary layer flow. In contrast, the increment in thermal radiation promotes heat transfer deterioration. Further, more than one solution is proven, which invariably leads to a stability analysis, which validates the first solution’s feasibility. Originality/value The present results are new and original for the study of flow and heat transfer on unsteady stagnation point flow past a permeable stretching/shrinking Riga plate in Al2O3-Cu/H2O hybrid nanofluid with thermal radiation.