A Study Of The Influence Of Side Slope On The Flow And Deposition Of Turbidity Currents In Submarine Canyons

The deposits from turbidity current are the hot spot of the world deepwater oiland gas field exploration and research, but field survey and lab experiment ofturbidity currents have many difficulties, numerical simulation is becoming one of theeffective ways of turbidity current research. A three-dimensional computational modelbased on Reynolds-averaged Navier-Stokes equation and buoyancy modifiedturbulence k model is used to study the flow and deposition of turbidity currentsin sinuous submarine canyons with different cross-sectional curvature radius anddifferent side slope.The finding are:(1) for bigger cross-sectional curvature radiusand gentle side slope, turbidity current within the channel are more likely to spillsover the bank of the channel apex and its downstream;(2) for smaller sectioncurvature radius and steep side slope, turbidity currents downstream in the channelremain high flow velocity and strength;(3) a common feature of the simulatedturbidity currents is erosion occurred in outer bank and deposition inner bank;(4)channels with arc cross section gradually transform to asymmetric trapezoidal shape;and side slope of trapezoidal channel became gentle;(5) at the bend apex ofchannels with gentle side slope, secondary flow is similar to that of rivers; for deepchannels with high side slope, there exists another secondary flow with opposite flowdirection on top of the bottom one;(6) the simulation found that to a certain extent,increasing the cross section curvature radius and increasing downstream slope havethe same effect on secondary flow;(7) erosion and deposition is largely influenced bythe secondary flow. These characteristics would help us understanding the evolutionof the seafloor topography and inferring the formation environment and mechanismaccording to the features of the turbidity current deposits.