A review of transverse curvature effect on friction force and leading-edge flow

The paper reviews the transverse curvature effect on the friction force on and the leading-edge flow around a cylinder subjected to axial flow. Skin friction coefficient (C_f) on the cylinder surface could be predominant functions of Reynolds number (Re_a, based on cylinder radius a), transverse curvature (a⁺, normalized by friction velocity U_τ), and boundary-layer thickness ratio (δ/a). The relationships between C_f, Re_a, a⁺, and δ/a are analyzed, established, and presented in the form of empirical formulations. The C_f at Re_a ≤ 2 × 10³ is mainly dependent on δ/a while that at Re_a > 2 × 10³ is largely contingent on Re_a. The gaps of research into the axial flow cylinder are pointed out, namely, the literature lack the experimental study on large transverse curvature (small a⁺).