Experimental Study And Numerical Simulation For The Flow Characteristics Of Open Channel Flow With Water Hyacinth

The sudden development of Water hyacindk in Yangtze River and the rivers, lakes and reservoirs which are located in the south of Yangtze River .It covers the surface of the water, takes up part of cross section area for floot flow, increases the flow resistance. When the water flow with Water hyacindk encounters barrier, it forms a "Dam" that leads to the water level increased, results a great hidden danger to the levee.Based on achievement of flow with partly vegetated channel of predecessors this paper ,we carried out vegetated river flow with water hyacinth in interior flume and some corresponding properties or characteristics in numerical simulation, studied the effection of large area covered surface water hyacinth on the river flood capacity, and the river water body structure, the impact of water flow.In physical model testing, according to the strength and turbulent Reynolds stress changes along the way, the river flow is divided into three zones : nothing covered but affected area, the front of water hyacinth area and the full development of the flow of water hyacinth area , In this three areas typical cross-section, the changes of the velocity distribution, water level, roughness, turbulent intensity, and Reynolds stress in different conditions, was analyzed.Under the direction of water depth changes in the structure of water, it divides into two areas: regional roots and regional rhizomes below; regional rhizomes below relative strength of turbulent change is small; in regional roots ,Section 7 changes little, but different from the area with no water hyacinth, those in the section 2 and the front of water hyacinth areas are significant change, particularly in the former. The changes of Reynolds stress and turbulence distribution are similar. With momentum theorem and the balance of the equation at a constant non-uniform flow, a formula for calculating the roughness.was drawed on in this paper.FLUENT was used to simulate. Porous Media simulate Water Hyacinth. Volume of Fluid (VOF) method was introduced to trace free-surface. The RNGmodel was used for turbulence modeling. Combined all of these, the 2-D water-air two-phase flow field in Channel area covered by Water Hyacinth was simulated, then higher free-surface position and velocity distribution were obtained. The simulated higher free-surface position and velocity distribution agreed well with the experimental result.