Abstract: A genuine variational principle developed by
Gyarmati, in the field of thermodynamics of irreversible processes unifying the
theoretical requirements of technical, environmental and biological sciences, is
employed to study the thermodynamical effects of viscous dissipation in laminar
magnetohydrodynamic (MHD) mixed convection flow over a vertical flat plate with
uniform suction and injection. The velocity and temperature distributions inside
the boundary layer have been considered as a simple polynomial function and the
principle is formulated. The Euler-Lagrange equations are reduced to coupled
polynomial equations in terms of boundary layer thicknesses. The velocity and
temperature profiles as well as the skin friction and local heat transfer
parameters are determined for different values of the governing parameters,
mainlythe buoyancy parameter the magnetic parameter the Prandtl number the Eckert number and suction/injection parameter For some specific values of the
governing parameters, the results agree very well with those available in the
literature. The present study establishes a high accuracy of results obtained by
this variational technique.
