We investigate the thermocapillary and solutocapillary instabilities in a self-rewetting liquid film that has a nonmonotonic variation of surface tension with temperature containing an insoluble surfactant at the interface. The dynamics of such a thin liquid film flowing axisymmetrically on a heated vertical cylinder is examined by deriving a set of coupled evolution equations for the film thickness and the surfactant concentration under the lubrication approximation. We perform a linear stability analysis of the steady film solution with a uniform surfactant concentration at the interface. The effects of solutocapillarity and quadratic thermocapillarity are analyzed in depth using $T_m$, the temperature at which surface tension is nearly minimum as the cutoff point, and $T_{0i,s}$, the interface temperature of the steady film. Beyond a critical value of the solutal Marangoni number ${\text{Ma}}_{\text{s}}$, the dispersion curve, featuring two extrema exhibits midwave instability that is characterized by two cutoff wavenumbers. The conventional thermal Marangoni effect switches to the anomalous/reverse Marangoni effect as $T_{0i,s}$ takes values greater than $T_m$. We perform a detailed parametric study to scrutinize the effect of thermal Marangoni number ${\text{Ma}}_{\text{T}}$, solutal Marangoni number ${\text{Ma}}_{\text{s}}$, Biot number Bi, Bond number Bo, and surface Péclet number ${\text{Pe}}_{\text{s}}$ on the stability of the base state. The Orr-Sommerfeld problem is formulated and solved numerically under the creeping flow condition for arbitrary wavenumbers. A comparison of the neutral curves obtained from the Orr-Sommerfeld problem and the lubrication model reveal excellent agreement for small wavenumber perturbations. The nonlinear simulations of the coupled set of partial differential equations (PDEs) for the interface and surfactant concentration demonstrate the modulation of interface deformation in the presence of temperature gradients and concentration gradients in the regular Marangoni regime, whereas such deformations are suppressed in the anomalous Marangoni regime.

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• Hydrodynamic instabilities
• Interfacial flows
• Lubrication theory
• Surface instabilities
• Surface tension effects
• Thin fluid films