Standard turbulence model,combined with Reynolds-averaged Navier-Stokes(RANS) equations,was used to study the turbulence structure of open channel flow through double layer rigid submerged vegetation.The calculated velocity distributions are in good agreement with test data,which proves the validity of the computational method.The velocity distribution,Reynolds stress,and turbulent energy distribution were derived by using the double-averaged(in space and in time) hydrodynamic equations.The vertical velocity distribution was divided into four regions by three turning points.The results showed that Reynolds stress and turbulent energy distribution dramatic increases at each top of the vegetation layer,and maximum value can be found near the taller vegetation.Turbulent dissipation and pressure dissipation play a leading role in the balance of turbulent energy equation.The vortex that generated at the top of vegetation results in a massive mass and momentum transfer through ejection and sweeps.
