Study on the evolution of initial field error in the simulation of river flow

In order to estimate the influence of the initial field error on the river simulation,the governing equation is developed by the small perturbation method in this paper.The analytical solution to the equation is derived according to the form of the seiche wave.The theoretical result shows that the initial field error is equivalent to an extra numerical wave imposed on the simulated river.The numerical wave exists as standing wave,whose length is four times of the simulated river length.Its period can be estimated by the Merian formula,where the friction impact can be neglected.The error wave disappears quickly, which reveals the strong dissipation of the velocity field.The analysis is validated by a numerical simulation in a natural river.