Thermocapillar instability of a two-dimensional viscoelastic planar liquid sheet in surrounding gas

Abstract

A two-dimensional viscoelastic planar liquid sheet subjected to a considerable temperature gradient perpendicular to the surfaces, moving in a gas medium, was investigated in a linear scope. The sheet instability was explored by solving the dispersion relation in the sinuous mode. Results suggested that the viscoelastic liquid sheet could behave with greater stability than its Newtonian counterpart when the temperature difference was sufficiently large. Thermal effects improved sheet instability, while the liquid elasticity had a dual effect when considering the temperature difference. It should be noted that thermal effects could retard the breakup process of viscoelastic planar liquid sheets at a large liquid Weber number. Deformation retardation time was a destabilizing factor when there were great temperature differences, which was polar to the case without thermal effects. However, the effects of liquid viscosity, liquid velocity, gas-to-liquid density ratio, and surface tension were analogous, whether or not there existed a difference in temperature. Finally, the competition between thermocapillar and aerodynamic instabilities on sheet instability was examined.