A fractional model for thermal investigation of MoS2-Fe3O4/engine oil hybrid nanofluid under double ramped conditions and shape factor influence: The Atangana-Baleanu approach

In recent times, the study of diathermal oils is an area of interest for multiple researchers because of their numerous pivotal applications in industrial and engineering operations. The core aim of this work is the formulation of a fractional model to anticipate improvement in thermal and flow characteristics of a particular kind of diathermal oils named engine oil due to the dispersion of two different types of nanoparticles. Molybdenum-disulfide (MoS2) and iron oxide (Fe3O4) nanoparticles are considered to form hybrid nanofluid, and combined impacts of their particular features on the thermal efficiency of engine oil are investigated. The ramped movement of an unbounded vertically inclined wall initiates the flow of hybrid nanofluid and some supplementary physical phenomena such as heat radiation, uniform magnetic field, and ramped heating also influence this flow. Additionally, the significant role of nanoparticles' shape factor in augmenting the heat transfer capacity of engine oil is examined. Initially, the flow of hybrid nanofluid is described through the Brinkman-type fluid model, which is developed in light of Maxwell equations and Boussinesq approximation. Later, this mathematical model is transmuted to a fractional framework by incorporating the time-fractional Atangana-Baleanu derivative. Laplace transformation is employed to procure exact solutions of the generalized model. These solutions are portrayed through several graphical illustrations to analyze the influence of various involved physical parameters. Special attention is given to heat transfer rate and shear stress, and a comprehensive tabular study is performed in terms of Nusselt number and skin friction coefficient. It is concluded that the heat-transferring potential of observed hybrid nanofluid is 17.4% higher than pure engine oil. The combination of fractional model and ramping technique is found to be more effective for increasing the heat transfer rate and reducing the shear stress.

Automated summary

The study formulates a fractional model to predict the impact of specific nanoparticles on the thermal efficiency of engine oil, investigates the flow characteristics of hybrid nanofluid, and highlights the significant role of nanoparticles' shape factor in enhancing heat transfer capacity.