Surface tension energy

$E_{\rm ST}$ [short dashed (red solid online) lines] and the capillary force

$F_{\rm cap}$ [solid (black solid online) lines] for a bubble as a function of the position of a bubble in two microjets with (a) and (b) lower and (c) and (d) higher degree of conicity at two values of the parameter

$r_{c}$: (a) and (c) 3.25 μm and (b) and (d) 4.00 μm. (The shape of the tubes is represented schematically in the insets with the geometric parameters.) Long dashed (blue dashed online) lines, which are drawn through the minima of

$E_{\rm ST}$ as a function of

$X$, separate the regions, where the bubble is deformed due to the confinement to the conical tube as shown in

Fig. 5 (at lager values of

$X$), from the regions of the spherical bubble (at smaller values of

$X$). In the inset to panel (c), the function

$E_{\rm ST}$$(X)$ is represented significantly magnified near to the position of its minimum, the decaying part is represented with a dashed (red dashed online) line. In all cases,

$\theta$ = 24° and

$L$ = 50 μm.