The thermocapillary-driven interface deformation and fluid flow in superimposed fluids

The goal of this study is to mimic the thermocapillary-driven flow of continuous fluid streams

in microchannels as a result of micropatterning of the heated wall, using Direct Numerical Simulations. To this end, we consider a

horizontal microchannel that is heated from below by imposing the upper wall to a uniform temperature

and the lower wall to a sinusoidal temperature that is higher (on average) than the temperature of the

upper wall. The equilibrium shape of the interface and the strength of the fluid flow are determined

as a function of the controlling nondimensional parameters of the problem. For small to moderate Marangoin numbers,

the interface settles to an equilibrium sinusoidal shape; however, depending on the ratio of the thermophysical properties, its sense of the deformation will be concave up

or down. Beyond a critical Marangoni number, the interface deforms continuously and does not settle to an equilibrium shape.