The Relative Stream Function of the Uniformly Moving Helical Vortex Tube

This paper is concerned with deducing an approximate expression for the relative stream function of the inviscid flow field induced by the single concentrated helical vortex tube that moves uniformly and rigidly without change of form in cylindrical straight pipe. In our previous discussion, the exact solution of the relative stream function is with infinite items, but now, the approximate solution with finite item is discussed, and so, the relative stream function can be calculated.