On the Stokes flow problem associated with a general twisted tube with a uniform non-rotating section (Q1063481)

The flow described in the title is a most complicated one. The author introduces a special orthogonal coordinate axes related to the geometry of the tube. Than he writes the Stokes equation in this system - a standard although troublesome procedure. The author claims that he found the solution in two particular cases: when the tube curvature is small or the torsion is small, using the perturbation procedure. It is however almost impossible to verify this claim; in fact no solution is presented but only formulae for successive approximations - the formulation of the problem ends the paper. One expects to find in a considered type of flow some most interesting features like reverse flows, dead zones etc. None of them is even mentioned in the paper.