Targeted drug delivery is one of the most promising aspects of cancer diagnosis and treatment. Gold nanoparticles are widely used for drug delivery and in the treatment of tumors, but due to the low absorption of infrared light, tumor cells get destroyed. However, iron‐oxide‐coated gold nanoparticles could be used for drug delivery to a targeted spot with the help of an external magnetic field. The present article aims to investigate the thermal instability of the blood flow transporting gold and iron‐oxide nanoparticles through the artery. The Casson fluid model is used to characterize the blood flow, and Maxwell equations, together with Navier–Stokes equations, are used to describe the flow behavior. Further, the linear stability theory and normal mode analysis are used to obtain the secular equation of the thermal Rayleigh number. The influence of pertinent flow governing parameters such as heat source parameter, Chandrashekhar number, the diameter of nanoparticles, and volume fraction of nanoparticles are discussed graphically on the convective instability of the system. The addition of gold nanoparticles makes the system unstable due to their large size and heat generation within the system. On the other hand, the magnetic field stabilizes the system by controlling the trajectory of the nanoparticles injected into the blood vessels.

The main objective of this study is to examine non-linear Bénard convection in a single-walled carbon nanotube suspension saturated in a rotating porous medium with an internal heat sink/source. The modified Buongiorno model is utilized to formulate the governing equations for the flow. Both linear and weak non-linear stability analyses are conducted in this investigation. The linear stability analysis employs the truncated Fourier series transformation, while the weakly non-linear stability analysis utilizes the Lorenz model, assuming weak thermophoresis, porous friction, and small-scale convective motion. The cubic Ginzburg-Landau equation is derived and further solved to obtain the amplitude expression. The influence of various parameters, such as the Taylor number, heat sink/source parameter, and viscosity parameter, is discussed in relation to the threshold criteria of convection, as well as heat and mass transport rates. Based on the linear stability analysis, it is concluded that the rotating frame of reference delays the onset of convection, while the energy supply to the system advances the onset of convection. The heat transfer rate increases by $22\%$ when the nanofluidic system is placed in the rotating frame of reference under the presence of an internal heat source.

The present study aims at discussing the onset of convection and heat transfer rate in a Casson nanofluid saturated in anisotropic porous enclosures of three types: shallow, square, and tall. The effects of Brownian motion and thermophoresis are included in the model. Normal modes are used to obtain the expression of stationary thermal Rayleigh number. Further, nonlinear stability analysis is performed using the truncated Fourier series expansion. The Nusselt number is calculated from the Lorentz model. The effects of pertinent flow governing parameters such as Casson parameter, thermal anisotropic parameter, mechanical anisotropic parameter, and nanoparticle concentration Rayleigh number are shown graphically on the onset of convection, Nusselt number, streamlines, isotherms, and isohalines. It is observed that shallow enclosure allows quick heat transfer by setting the convection earlier. Furthermore, it is concluded that the use of Casson-based single-walled carbon nanotube suspension (SWCNTS) enhances heat transportation and strengthens the magnitude of streamlines.

This study aims to investigate the influence of chemical reactions and anisotropic porous material on the convective instability, heat and mass transfer rate of water-based carbon nanotube suspension. Flow governing dynamics are modeled using the modified Brinkman–Buongiorno model. The effects of pertinent flow characterizing parameters such as chemical reaction parameter, porosity parameter, mechanical anisotropy parameter and thermal anisotropy parameter on the threshold of convection, heat and mass transport rate are discussed and compared for three types of enclosures: shallow, square and tall. The study concludes that nanoliquid suspended with single-walled carbon nanotubes has higher heat and mass transfer capability than the multi-walled carbon nanotubes when saturated in a tall porous enclosure and also tall enclosure allows the convection to set in earlier. Anisotropic effect and destructive chemical reaction delay the starting of convection. Further, it is observed that the heat transfer rate decreases with the chemical reaction parameter.