Numerical study of flow patterns in a portion of Saigon River in Hochiminh City

Abstract

Aiming to understand effects of secondary flows on bank erosion and failure in curved rivers, we are coflducting both experiments and numerical computations for the most curved portion of Saigon River in Hochiminh City. In the experiments, physical distorted hydraulic model of the river is built at scales of 1 :500 horizontally and 1: 100 vertically. In the computations, both two-dimensional and three- dimensional models are made. This paper presents preliminary results of a two-dimensional computational hydraulic model. The computations are conducted for domains identical to those of the physical hydraulic model. Governing equations are depth averaged ones describing conservations of mass and momentum. Unstructured grids together with finite element method are employed. Boundary conditions are discharge at the inlet and water level at the outlet of the computational domain. The model is first validated by the test case conducted by Jovein et al (Jovein E. B. et al, Experimental Study on Flow Structure in Strongly Curved Open Channel 90-degree Bends, International Symposium on Water Management and Hydraulic Engineering Ohrid/Macedonia, 1-5 September 2009, Paper A32). Compared data include flow velocity and water level at specific sections. The validated model is then applied to the scaled Saigon River with five different discharges with Froude numbers similar to those in the real river. The computational results show velocity distributions and water levels at twenty sections. Locations of highest velocity and bed shear stress are also seen.