Unsteady stagnation-point flow of a hybrid nanofluid over a spinning disk: analysis of dual solutions

This paper is concerned about the characteristics of the dual solutions of an unsteady stagnation-point flow of a hybrid nanofluid over a rotating disk with the effect of Hall current. The governing equations are non-dimensionalized using the appropriate similarity transformations. The resulting equations are solved numerically by employing the bvp4c method. A comparison between the present solutions with the available solutions is presented which shows an excellent agreement. The solution exists in the upper branch for all values of the hybrid nanofluid phi(1), phi(2), the swirl parameter Omega(A), and impinging parameter beta(A). However, the breakdown is observed in the lower branch solution at some moderate values of beta(A). In addition, the radial velocity increases due to hybrid nanofluid, while the azimuthal velocity decreases. However, the temperature increases due to hybrid nanofluid. Moreover, the results also indicate that the swirl parameter augments the velocity in both directions but declines the temperature. Also, it is perceived that the azimuthal velocity and temperature decrease in the upper branch solution as the magnetic parameter increases, while the lower branch solution initially increases and then decreases for the transverse component of velocity but the temperature monotonically increases.