Abstract
This paper discusses the magnetohydrodynamic mixed convection boundary-layer stagnation point flow of a nanofluid towards a stretching surface in the presence of both nanoparticles and gyrotactic microorganisms. The governing boundary-layer equations of the problem are formulated and transformed into a self-similar form. The obtained equations are solved numerically by an efficient, iterative, tri-diagonal, implicit finite-difference method. The results from this investigation are well validated and have favorable comparisons with previously published results. The obtained results are presented in terms of profiles of the velocity, the temperature, the nanoparticles volume friction and the rescaled density of motile microorganism as well as the local skin friction coefficient, the local Nusselt number, the local Sherwood number and the local density number of the motile microorganisms. It is found that the magnetic field suppresses the dimensionless velocity and increases the dimensionless temperature inside the boundary layers. Also, the bioconvection parameters tend to reduce the concentration of the rescaled density of motile microorganisms.