## Abstract

We consider the translation of a rigid, axisymmetric, tightly-fitting object through a fluid-filled, cylindrical, elastic tube under applied axial and normal

stresses. The intruding object is assumed to be slender and greater in size than the nominally undeformed tube radius, forcing solid-solid contact in

the absence of relative motion between the surfaces. The motion of the object establishes a thin liquid film that lubricates this contact. We show that for small translation speeds, the force on the intruding object depends on the slope of its surface at the entrance region to the thin fluid film, and scales as the square root of the relative speed. As a consequence, asymmetric intruders experience a lower force when traveling narrow-end-first through soft tubes. We then

analyze the effect of the axial tension in the tube, which is caused by the friction between the intruding object and tube itself. In the limit of small speeds,

this tension leads to a reduction in the drag on the intruder, with this effect being reversed at larger speeds. This correction due to tension disappears in the limit of small deformation relative to the tube radius.

stresses. The intruding object is assumed to be slender and greater in size than the nominally undeformed tube radius, forcing solid-solid contact in

the absence of relative motion between the surfaces. The motion of the object establishes a thin liquid film that lubricates this contact. We show that for small translation speeds, the force on the intruding object depends on the slope of its surface at the entrance region to the thin fluid film, and scales as the square root of the relative speed. As a consequence, asymmetric intruders experience a lower force when traveling narrow-end-first through soft tubes. We then

analyze the effect of the axial tension in the tube, which is caused by the friction between the intruding object and tube itself. In the limit of small speeds,

this tension leads to a reduction in the drag on the intruder, with this effect being reversed at larger speeds. This correction due to tension disappears in the limit of small deformation relative to the tube radius.

Original language | English |
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Journal | Journal of Fluid Mechanics |

Publication status | Submitted - 22 Dec 2020 |