Numerical study of the effect of partial undulations of horizontal isothermal walls on the behavior of a binary fluid in a modified horizontal rectangular cavity

The influence of partial sinusoidal undulations on the horizontal, isothermal, impermeable walls of a modified horizontal rectangular cavity, with a shape factor A= 10, filled with a binary fluid heated from the bottom or top, on the hydrodynamic, mass and thermal behavior of the considered fluid, was numerically studied. Computational fluid dynamics based on finite element methods was used to establish the numerical simulation of the differential equations governing the coupling of natural convection and thermodiffusion. The numerical results show that the partial undulation of the horizontal walls affects the hydrodynamic behavior of the binary fluid, leading to species migration towards the perfectly insulated vertical walls of the cavity. The numerical control of the mass field of the studied fluid clearly shows that the intensity of species separation towards the two vertical walls increases with bottom heating and with increasing length of the undulated portion Lw and the undulation amplitude a. The variation of the length of the undulated portion Lw and the amplitude of the undulation a also have an impact on the heat transfer presented by the Nusselt number Nu.