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Mine Impact Burial Prediction From One to Three Dimensions

The Navy's mine impact burial prediction model creates a time history of a cylindrical or a noncylindrical mine as it falls through air, water, and sediment. The output of the model is the predicted mine trajectory in air and water columns, burial depth/orientation in sediment, as well as height, area, and volume protruding. Model inputs consist of parameters of environment, mine characteristics, and initial release. This paper reviews near three decades' effort on model development from one to three dimensions: (1) one dimensional models predict the vertical position of the mine's center of mass (COM) with the assumption of constant falling angle, (2) two-dimensional models predict the COM position in the (x, z) plane and the rotation around the y-axis, and (3) three-dimensional models predict the COM position in the (x, y, z) space and the rotation around the x-, y-, and z-axes. These models are verified using the data collected from mine impact burial experiments. The one-dimensional model only solves one momentum equation (in the z-direction). It cannot predict the mine trajectory and burial depth well. The two dimensional model restricts the mine motion in the (x, z) plane (which requires motionless for the environmental fluids) and uses incorrect drag coefficients and inaccurate sediment dynamics. The prediction errors are large in the mine trajectory and burial depth prediction (six～ten times larger than the observed depth in sand bottom of the Monterey Bay). The three-dimensional model predicts the trajectory and burial depth relatively well for cylindrical, near-cylindrical mines, and operational mines such as Manta and Rockan mines.