Numerical Investigation of Boundary Layer Separation in a 3-D Divergent Channel under the influence of a non-Uniform Magnetic Field

In the present research, the non-uniform magnetic field effect on separation phenomenon in divergent channels was investigated numerically. The governing equations, including continuity and momentum equations, were presented and simplified for the laminar, steady, and incompressible flow; then, a non-uniform magnetic field was applied to the flow. Hence, the finite volume method using the OpenFOAM CFD toolbox was employed and a code for 3-D divergent channel flow under a non-uniform magnetic field developed. The effect of non-uniform magnetic field intensity on the boundary layer separation phenomenon on the divergent channel wall was investigated. The results show that the separation in the flow without applying a magnetic field occurs in Re=250 on the channel's upper (lower) wall. By applying the magnetic field and increasing the Hartmann, the boundary layer separation was delayed and in Ha equals 4, the separation is completely deleted and not observed. Under the same conditions, near the sidewalls, the separation occurs sooner than the channel entrance. Furthermore, by reducing the Reynolds to 208.33, the separation occurs late. In a 3-D channel that has a width ten times bigger than its height, the separation points far from the side walls are almost the same as a 2-D channel.