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. The influence of particles adhering to the rectangular riblets on the drag reduction effect is investigated. The 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, we calculate the detailed particles motion and the adhesion position of the particles to riblets in the turbulent channel flow. Second, the riblet shape is modified based on particle adhesion distribution. Here, the condition that the particle adhesion distribution is uniform in the streamwise direction and independent of the number of particles adhered is given. Third, we calculate the flow over the riblet with the adhered particles. As a result, most of the particles adhered to the top wall and the upper half of the side wall surfaces of the riblets. Due to the particle adhesion on the riblets, the drag increases as compared with the case of the initial riblet of the riblet.