Experiment And Numerical Research Of Flow Structure Around Spur Dike

With the constant construction of hydraulic projects, the spur dike as the major means of river channel training becomes increasingly widespread application. Un-derstanding the water flow structure near spur dike correctly provides instructional advice for the optimization of the spur dike head patterns, identifying its size and distance .The flow near the spur dike is obviously three-dimensional and turbulent, although there are much studies of flow structure near the spur dike study at home, most studies are about time-averaged value, while there is little study about instan-taneous value, so the turbulence mechanisms have yet to be further developed.The paper research about flow structure near the spur dike involves flume ex-periments and numerical simulation, which are based on predecessors'studies. The experiment contents are three-dimensional instantaneous velocities measure- ments in typical transection of upstream and downstream along overflow spur dike,single non-submerged spur dike and double spur dike, which are carried out by Acoustic Doppler Velocimeter produced in America Sontek company, we can get some infor-mations about average velocity,turbulent density and kinetic energy through data processing by WinADV, analyzing and summarizing those parameters distribution in space, understanding turbulence mechanisms near the spur dike preliminmarily.When spur dikes are built on river bank, the streamline will be concentrated, the local flow structure will be changed, these are some complicated flow phenomenon such as separate flow,reverse flow,curve shear layer,high turbulent flow and moving boundaries and etc. It is necessary to choose appropriate turbulence model in order to describe those complicated phenomena. This paper simulates the spur dike flow in flume by 2-D depth-averaged k-εturbulence model and large eddy model, comparing the former computed results with the latter and analyzing which factors to influence the recirculation length of the spur dike. According to similitude law, the computation carries out again with rectangle transection of a large scope water flow to check up the 2-D depth-averaged large eddy model. At last, the 2-D depth-averaged large eddy model is established in orthogonal curve coordinates to compute the flow under the moderate water level and low water level in the natural channel of Luotan downstream of RongJiang river, GuangXi province, the computa-tion results are displayed as the form of dynamic flow field by the data visualization technology , which provides referenced advices for further channel regulation.