A Study On The Influence Of The Fluctuating Velocity's Amplitudes Near The River-bed On The Change Of The River Terrian

The to carrying sand flow measurement of the near bottom velocity as the research sample,the use of mathematical statistics,stationary random process theory,the theory of differential and integral calculus,the motion of the fluid mechanics discipline analysis,near bottom velocity probability model,and near the end of the acceleration and pressure fluctuation probability model is established.The main research contents and results are as follows:First,using random distribution theory analysis,found in sediment laden near bottom velocity data meet the research requirements,and follow the smooth random process and the state after sex.By using the experimental data obtained from the time and frequency domain,it is found that the near bottom velocity is low frequency domain signal,and the frequency domain is less than 20 HZ,and the energy is less than 10 HZ.Second,will after filtration of the near bottom velocity were fast Fourier conversion,the probability of the amplitude,phase angle and circular frequency distribution analysis,found that the amplitude with normal distribution,the frequency with uniform distribution,the phase angle roughly in line with uniform distribution,due to the near bottom flow is turbulent flow,with variability,so each parameter probability distribution will have a certain deviation,but within the error range,satisfy the requirement of accuracy.Third,the stationary random process theory,near bottom velocity signal probability model is established,found near the bottom of the velocity of the simulated data and the original sample data are basically consistent.Finally the model weight adjustment,found near bottom velocity at the end of the analog signal and the original sample signal can agree well and meet the accuracy requirements.Fourth,the use of near bottom velocity probability model simulated data and the raw data compared to the analysis,found that the simulated data appear larger sources of error in the near bottom turbulence is reinforced and the velocity variation;experimental velocity data,the rocks rolling,eddy currents are generated;near bottom velocity probability density does not meet the symmetry;part sample function section is used for collecting the relatively short,the results can not correct said the particle velocity near the bottom of the characteristics of;data acquisition did not consider near bottom negative velocity.Fifth,establishment of near bottom pressure fluctuation probability model,obtain the spectrum of pressure fluctuation,and then,by using the simulated signal statistics analyze the features of their own values,and then simulate the near bottom velocity fluctuation spectrum,finally with the original measurement data signal contrast and found that the simulation results are reliable.Sixth,the turbulent intensity of the near bottom water is the largest,and the minimum is near the water surface.However,under the condition of small flow velocity,the turbulence intensity of near bottom turbulence intensity is smaller than that of other depths,with the increase of flow velocity,the intensity of the near bottom turbulence increases sharply,and the turbulence intensity is much larger than other depths.Seventh,in low flow conditions,the near bottom flow energy fluctuation with the increase of flow rate increases,and when the flow exceeds a certain amount of energy will increase sharply.Near the end of the fluctuating pressure at low flow rate,little change of fluctuating pressure,only a small range of fluctuations,when the flow reaches a certain limit,the fluctuating pressure increases rapidly,which caused serious erosion.