平行平板間乱流における粒子付着によるリブレットの抵抗低減効果の変化

抄録

Numerical simulations of fully developed turbulent channel flows with riblet surfaces were carried out at the friction Reynolds number of 180. Influence of particles adhering on the blade-type riblets on the drag reduction effect is investigated. A one-way coupling method is employed: the particles are affected by the fluid, but the fluid is not affected by the particles. The simulation consists of three steps: first, calculation of the adhesion position of the particles to the riblets in the turbulent channel flow; second, the riblets shapes are changed based on the particle adhesion; third, calculation of the turbulent flow over the particle adhered riblet. As a result, most of the particles adhered to the upper wall and the top of the side wall of the riblets, while number of the particles adhering to the vicinity of the channel wall is very small. Due to the particle adhesion on the riblet, the drag increases as compared with the clean riblet case and the plane channel flow. We confirmed that the Reynolds shear stress profile is to be consistent with the drag variation.