Thermocapillar instability of liquid sheets in motion
Por:
Dávalos-Orozco L.A.
Publicada:
1 ene 1999
Resumen:
In this paper the linear thermocapillar instability of a viscous liquid sheet in motion through a gas which has two free deformable surfaces with different temperatures is investigated. This temperatures difference is supposed to be due to a temperature gradient in the ambient gas. It is found that thermocapillar instability affects in an important way the viscosity-enhanced instability investigated by Li and Tankin (J. Fluid Mech. 226, (1991) 425). For the sinuous mode and small Weber numbers the viscosity destabilizes and thermocapillar effects destabilizes through the Marangoni number coupled to the Ohnesorge number, representing Viscous effects. The thermocapillar instability has growth rates far more larger than those of the pure viscosity-enhanced instability. For large Weber numbers Li and Tankin showed that the viscosity stabilizes and that the aerodynamic instability is the more important, however thermocapillarity destabilizes increasing the growth rates with the Ohnesorge number in such a way that for some Marangoni numbers the thermocapillar instability is the more important. Plots of the maximum growth rate against the Marangoni number are given in which new features of this maximum are observed such as a steep increase of its magnitude in a relatively small range of Marangoni numbers due to the onset of thermocapillary convection. It is shown that from the thermocapillar point of view the Weber number plays a stabilizing role. The varicose mode can not be changed notably by thermocapillarity and the curves almost remain the same as those of the pure viscosity-enhanced instability. For large enough values of the Marangoni and Ohnesorge numbers the sinuous mode has the larger maximum growth rate.In this paper the linear thermocapillar instability of a viscous liquid sheet in motion through a gas which has two free deformable surfaces with different temperatures is investigated. This temperatures difference is supposed to be due to a temperature gradient in the ambient gas. It is found that thermocapillar instability affects in an important way the viscosity-enhanced instability investigated by Li and Tankin (J. Fluid Mech. 226, (1991) 425). For the sinuous mode and small Weber numbers the viscosity destabilizes and thermocapillar effects destabilizes through the Marangoni numb
Filiaciones:
Dávalos-Orozco L.A.:
Inst. de Invest. en Materiales, Univ. Nac. Auton. Mex., Apdo. P., Coyoacán, Mexico
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