二相系格子ボルツマン法を用いた流体中における粘弾性皮膜固体の挙動解析（内部流体の粘度が固体の挙動に与える影響について）

概要

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The behavior of a deformable body with a viscoelasitc membrane in fluid flows is numerically investigated by the two-phase lattice Boltzmann method. In the calculations, the internal fluid of the body is distinguished from the surrounding fluid so that the viscosities of these fluids can be separately specified. Using this method, the deformation of the body under a shear flow is simulated by changing the viscosity ratio η, which is defined as the ratio of the viscosity of the internal fluid to that of the surrounding fluid. It is found that as the viscosity ratio increases, the deformability of the body remains almost constant for 0.1 ≤ η ≤ 1, whereas it decreases linearly for 1 < η ≤ 10. In addition, the behavior of the body in a square pipe flow is simulated for various viscosity ratios. The velocity near the centerline of the pipe decreases with increasing the viscosity ratio, and thus the flow rate becomes reduced. In the case of lower viscosity ratio (0.1 ≤ η ≤ 1), the body becomes a parachute-like shape and approaches toward the centerline of the pipe; that is, axial accumulation is observed. In the case of higher viscosity ratio (e.g., η = 6), the body forms into a slipper-like shape, migrating laterally toward a certain equilibrium position between the wall and the centerline of the pipe.