“…Flow patterns in curved tubes have important applications to problems in engineering and aerosol science and technology, for example, heat and mass transfer (Mori and Nakayama, 1965;Dravid et al, 1971;Cheng and Takuma, 1991;Choi and Park, 1994) and analyses of particle movement in curved pipes and aerosol instrumentation (Crane and Evans, 1977;Stober and Hederer, 1978;Martonen, 1982;Willeke and Baron, 1993). Quite different from flow in a straight tube, flow in a curved tube has secondary motion in the plane perpendicular to the axial (i.e., longitudinal) motion of flow, and the axial flow itself is skewed rather than parabolic.…”