Recent advancements in river flow modeling

Recent advancements in river flow modeling focused mainly on the ones made in Korea, encompassing 1D, 2D, and 3D models, are introduced. One of the main concerns in the 1D flow modeling has been to develop a new, robust method for simulating the discontinuous flow such as hydraulic jump. A new implicit upwind model with an appropriate treatment of the source terms has been proposed and tested to various discontinuous flows. This new model shows a very good stability and robustness compared with existing ones. A 2D river flow model has been recently introduced for simulating flows in the vegetated channel. In this model, the shallow water equations are solved numerically using the 2D characteristic dissipative-Galerkin method. In order to take account of vegetative resistance, the drag force terms are included in the flow equations. The model is also capable of computing the morphological change in the river. The effect of gravity force due to geometry change and secondary currents are also considered in the model especially for simulating the bed elevation change in a bend. For 3D computations of the open-channel flow, a Reynolds-averaged Navier-Stokes model has been proposed. The Reynolds stress model is used for the turbulence closure. The model has been applied to various types of open-channel flows, including rectangular channel flows, partly-vegetated flows, flows over smooth-rough bed strips, and compound channel flows. Simulated flow structures are presented and compared with measured data in the literature.