Experimental Study On Evolution Law Of Thin Layer Rolling Flow On Slope Surface

As the main dynamic factor of soil erosion on slope,the flow characteristics of slope are affected by flow,slope,surface condition,rainfall and so on.Under certain hydraulic conditions,the surface of the slope will be unstable and produce rolling waves.The generation of the rolling wave will also have a great influence on the hydrodynamic characteristics of the overland flow and the mechanism of soil erosion.At present,on the slope of water dynamics there is still much controversy,studied under the Reynolds number range is too narrow,which makes the research of flow and resistance characteristics is not comprehensive enough,and can not give a definite conclusion,also to be explored further for the influence factors of roll waves and evolution.Ultrasonic rolling wave measuring system the selection of water and glycerin as test fluid,expand the Reynolds number range,with the increase of liquid viscous coefficient to highlight the roll wave evolution,and the evolution of non steady state rolling wave slope water dynamic characteristics of 4 different roughness,5 grade,13 single wide flow conditions the research results show that:(1)Flow pattern and resistance characteristics of hillslopeGlycerol solution under the experimental conditions,the m value range of 0.256~0.497,the slope has little effect on the m value,flow coefficient m value with the increase of roughness increases first and then decreases;the water under the experimental conditions,the m value range of 0.350~0.562,the m value increases with slope and roughness increased first then decreased;glycerol solution under the conditions of N were larger than that of water under the experimental conditions of n value,when the Reynolds number is small,can affect the average depth of the slope for more significant;different roughness conditions,the drag coefficient in logarithmic coordinates for a set of parallel lines with slope and Reynolds numbers the.The value of the resistance increases with the increase of roughness and slope,and decreases with the increase of Froude number.(2)Influencing factors of characteristic parameters of rolling wave on slope surfaceWith the increase of discharge per unit width,roll wave speed in power function increases gradually,the relative velocity decreases gradually,the change trend of roll wave crest and relative wave height showed monotonically increasing,rolling wave frequency in large slope conditions appears to decrease with the increase of slope;energy,rolling wave velocity increases gradually,roll wave peak roll wave decreases,relative wave height change,roll wave frequency increases;with the increase of roughness,rolling wave speed increased first and then decreased,the peak depth roll wave showed a trend of decreased first and then increased,the relatively high roll wave wave decreases first and then increases and then decreases,roll waves the frequency of first increased and then decreased;rolling wave velocity and wave crest depth by single roll discharge,said slope and roughness to the power function relationship,empirical equation coefficients are respectively 0 92 and 0.91,compared with the boiling wave produced under the condition of clear water,the wave velocity produced by the glycerol solution is smaller and the peak value of the rolling wave is greater.(3)The evolution law of rolling wave waveform and relative characteristic parametersWith the increase of the flow rate of single width,the roll wave shape develops in a high and steep direction.After the increase of the slope,the rolling wave changes to a short,slender and narrow feature.Increased roughness after roll wave peak is relatively smooth,the body wave becomes wider;the whole process within the range of relative velocity changes little,but the energy slope is in the range of 0.1736~0.4226,the relative velocity in the 6.5m slope will appear a peak;the slope length is less than 6.0m,the relative roll waves wave height with the slope length increases,the growth rate decreases gradually with the increase of slope.In the range of 6.0~8.0m slope,rolling wave relative wave height trend is not obvious;with the increase in slope length,rolling wave relative water depth decreases with the increase of slope,decreasing rate gradually decreases;with the increase of slope length,the frequency will decay,enhanced polymerization.The rolling wave frequency attenuation rate decreases gradually with the increase of the slope,and the more smooth the slope is,the aggregation of the rolling wave occurs.