Instability of capillary jets with thermocapillarity

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Abstract
Long axisymmetric liquid zones are subject to axial temperature gradients which induce steady viscous flows driven by thermocapillarity. The approximately parallel flow in a cylindrical zone is examined for linearized instabilities. Capillary, surfacewave and thermal modes are found. Capillary breakup can be retarded or even suppressed for small Prandtl number and large Biot number B, which measures heat transfer from the liquid to the surrounding atmosphere. In the limiting case B → ∞ the zone becomes an isothermal jet subject to axial ‘wind stress’ on its interface. It is then possible to suppress capillary breakup entirely so that one can maintain long coherent jets.