하천단면에 따른 확산 분석에 대한 수치모의 연구

Abstract

ABSTRACT

Numerical Simulation of Dispersion Coefficient at Cross Section of a River

Oh, Hyeong seok Master of Science in Civil Engineering Hanyang University, 2011 Advisor : Professor Cho, Yong-Sik

The diffusions of flexure in meandering channels are investigated in this study. To analyze the diffusion due to sectional shapes, proper diffusion coefficients are required at meandering channels. To analyze the diffusion coefficient in meandering streams, dispersion coefficients have been calculated by using laboratory measurements as used in Guvmer (1998). While dispersion coefficients were calculated by using an empirical formula. Relative sizes of dispersion and diffusion coefficients were analyzed and diffusion features in two different channels were also examined by using RMA-4. It is assumed that boundary conditions were same except for bottom section and diffusion coefficient of meandering channels to compare and stimulate the differences of diffusion features of meandering channels depending on bottom section. Dispersion coefficients calculated in this study are 0.986 for a trapezoidal channel and 0.0147 for a natural channel. Using calculated dispersion coefficients and RMA-4 model, it is verified that ratio of horizontal direction diffusion coefficient about longitudinal direction diffusion coefficient is proper when it is about 1/40 in Trapezoidal channel and 1/35 in Natural channel. It is also verified that diffusion depending on bottom section is faster in Natural channel than Trapezoidal channel. Maximum concentration of pollutant was little bit higher in the Natural channel, but when it is compared in same times, concentration of pollutant in natural channel is getting lower.