Hydraulic Characteristic Research Of Shallow Flow On Fixed Bed Slope Surface Resistance

Shallow flow on slope surface is a main driver of soil erosion process and its hydrauliccharacteristics is the basis of the erosion rule, but because of the flow is affected by naturalconditions of irregular topography, rainfall disturbances and outside constraints such as testequipment technology use, causes the hydraulic condition is complex, experimental study onthe difficulties, it is also in doubt. Therefore, on the basis of predecessors’ research, this paperadopts a new method for further exploration and research.The paper combines computer numerical simulation software and the hydraulic modeltest methods to exploration and research the hydraulic characteristics change rule of shallowflow on slope surface. At the same time based on the numerical simulation data as the basis oftest measuring distance and the size design,after the test, try to get discrimination andreflect shallow flow on slope surface defined new method.The FLUENT software as a new exploration way of the subject research, according tothe different underlying surface of shallow flow on slope surface conditions, ignore outsideinterference conditions such as rain, by hydraulic model tests with fixed bed resistance as theidea to set the boundary conditions, The volume of fluid(VOF) method are used to track thefree surface of shallow flow on slope surface, combined with standard k-ε turbulent model tosimulate the hydraulics characteristics parameters of air-water multiphase flow under differentdegress of roughness bed.The simulation software can accurately calculate the shallow flow on slope surfaceaverage speed, and through the XY analysis diagram that stable flow direction along thelength of the fixed bed flow time only for a few seconds, and the stability of the flow speeddistance is reduced with the decrease of the flow, when the average flow velocity of1.5m/s,stable distance of3.5m. Above the measurement data are the basis of design the model sizeand determine the velocity measurement.Through fixed bed resistance numerical simulation test, the same flow rate and bedsurface roughness, with the increase of slope, average flow velocity, Reynolds number Re, thefroude number Fr and resistance coefficient increase in small increments, which indicates thatwith the increase of slope, slope flow state tend to drag square area. When the same slop andthe different bed surface, with the increase of bed surface roughness, the drag coefficientincreases, the water consumption of energy increase, the flow velocity, Reynolds numberdecreases, and the water is from the jet stream to flow. Above conclusion is consistent withexisting literature results, verify the correctness of the numerical simulation method andshowed the importance of the shallow flow on slope surface surface tension by comparing, atthe same time it provides a new idea for the further research of flow pattern discriminationand the surface tension of quantitative description. Application theory of open channel flow of the model test are used for simplifing theshallow flow on slope surface, Renault simulation test, fixed bed resistance water experimentare carried out, that on the same bed surface conditions, with the increase of flow rate,average flow velocity, water depth all shows a trend of increase with the increase of flow, butboth are no significant change with the increase of slope, therefore they can approximate inthe expression that the only as the function of flow rate, and a good power functionrelationship. With the increase of flow,Reynolds number Re, the Froude number Fr are alsowith the flow rate was positively development potential, but the relationship with the slope isnot obvious, and the drag coefficient decreases with the increase of flow rate, but increaseswith the increase of slope, this mean that flow energy consumption also is larger with theincrease of slope.Measured in experiment by simulating Renault average, the ration of shallow flow onslope surface average velocity and the surface edge flow velocity change with the flow andslope all have different values, under the shallow flow on slope surface can be measured thevalue of the critical Reynolds number is about700.