A new theoretical tri-hybrid nanofluid model for enhancing the heat transfer is presented in this article. This model explains the method to obtain a better heat conductor than the hybrid nanofluid. The tri-hybrid nanofluid is formed by suspending three types of nanoparticles with different physical and chemical bonds into a base fluid. In this study, the nanoparticles TiO2, Al2O3 and SiO2 are suspended into water thus forming the combination TiO2-SiO2-Al2O3-H2O. This combination helps in decomposing harmful substances, environmental purification and other appliances that requires cooling. The properties of tri-hybrid nanofluid such as Density, Viscosity, Thermal Conductivity, Electrical Conductivity and Specific Heat capacitance are defined mathematically in this article. The system of equations that governs the flow and temperature of the fluid are converted to ordinary differential equations and are solved using RKF-45 method. The results are discussed through graphs and it is observed that the tri-hybrid nanofluid has a better thermal conductivity than the hybrid nanofluid.

In the current study, the bioconvective flow of Ree–Eyring through an expanding sheet with the porous medium is analyzed by considering the inclined magnetic field and gyrotactic microorganisms. Buongiorno's model, which defines the two major mechanisms; thermophoresis and Brownian motion is used to frame the mathematical model. The presence of motile cells helps in stabilizing the nanoparticle and avoids the sedimentation due to nanoparticles. The mathematical model with these assumptions is framed using partial differential equations (PDE) that are later remodeled to ordinary nonlinear differential equations by incorporating desirable similarity transformation. The equations so obtained shall be solved using DTM and the outcomes are described through graphs and tables. The graphs indicated that the velocity of the nanofluid flow reduces with the increase in the porosity and similarly, the higher values of Peclet number (Pe) are found to diminish the motile density. Whereas the increase in the thermophoresis parameter enhances the thermal and mass profiles of the nanofluid.