Herschel-Bulkley Fluid Flow through an Annular Geometry with a Helically-Buckled Inner Pipe

A correct prediction of drilling fluid pressure drop is considered as a key parameter to carry out an efficient drilling operation and avoid non-productive time (NPT) during enrollment of the process. In this paper, a numerical approach is employed to analyze frictional pressure loss of Herschel-Bulkley (yield power-law) fluid flowing through an annular geometry in which the inner pipe makes a helical buckling motion in laminar and turbulent regimes. Results showed that rotation of the helically-buckled inner pipe induces a decrease of 10% and 6% of the pressure loss gradient of the Herschel-Bulkley fluid in the laminar regime for the helical pitch lengths of 6.9 m and 10 m, respectively. Also, increasing the pitch length of a helically-shaped inner pipe reduces the pressure loss gradient, particularly for low angular speeds. Moreover, the helical pitch length increment from 6.9 m to 10.7