Turbulent flow in a square duct with strong curvature

摘要: The steady, incompressible, isothermal, developing flow in a square-section curved duct with smooth walls has been investigated. 40 × mm had radius ratio of 2·3 long upstream and downstream straight ducts attached. Measurements the longitudinal radial components mean velocity, corresponding Reynolds-stress tensor, were obtained laser-Doppler anemometer at Reynolds number 4 10 various cross-stream planes. secondary velocities, driven mainly by pressure field, attain values up to 28% bulk velocity are largely responsible for convection stresses plane. Production turbulent kinetic energy predominates close outer-radius wall regions negative contributions production exist. Thus, bend angle 90° near inner-radius wall, $\overline{u_{\theta}u_r}\partial U_{\theta}/\partial r$ is positive represents contribution generation energy. In spite complex stress distributions, controlled centrifugal force, gradient imbalance. As consequence, calculated results from solution elliptic differential equations finite difference form incorporating two-equation turbulence model not strongly dependent on model; numerical errors greater importance.