The Effect of Curvature and Torsion on Steady Flow in a Loosely Coiled Pipe

Abstract

A number of hemodynamic studies have already indicated that there is a relationship between the development of vascular diseases (e.g., atherosclerosis, intimal hyperplasia and thrombosis) and the local hemodynamic factors. Steady flow in the loosely coiled helical pipes is investigated, which is motivated by physiological and clinical applications. The objective of this study is to improve understanding of the influence of geometrical curvature and torsion on flows in helical pipes, in which the radius of pipe is much larger than the distance from the center of the pipe to the center of the helix. The three-dimensional computations of steady flows in the loosely coiled helical pipe are performed using a Navier-Stokes equation solver, which is based on spectral/hp element method for high accuracy. In this study, it is noted that the position of the maximum axial velocity component is influenced more by the curvature than by the torsion. It turns out that the effect of torsion on the axial flow is relatively minor, although torsion can radically influence the asymmetric pattern of the transverse flow and coherent vortical structures in a helical pipe. The ensuing results can provide hemodynamic information (i.e., vortex formation, mixing performance and wall shear stress distribution) within the loosely coiled vessels, so that clinical applications such as the design of stents and the model of synthetic bypass graft vessel to enhance the mixing of blood flow may be proposed.