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Browsing by Author "Jung, Seyong"

Now showing 1 - 3 of 3
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    An Approach for Computing Parameters for a Lagrangian Nonlinear Maneuvering and Seakeeping Model of Submerged Vessel Motion
    Jung, Seyong; Brizzolara, Stefano; Woolsey, Craig A. (IEEE, 2021-07-01)
    In this study, hydrodynamic forces on a submerged vessel maneuvering near a free surface are determined using a reformulated Lagrangian nonlinear maneuvering and seakeeping model derived using Lagrangian mechanics under ideal flow assumptions. A Lagrangian mechanics maneuvering model is first reformulated to simplify the computation of parameters; then, incident wave effects are incorporated into the reformulation; finally, the parameters are computed using a medium-fidelity time-domain potential-flow panel code. Predictions from the reformulated Lagrangian nonlinear maneuvering and seakeeping model, whose parameters are computed using the methods described here, are compared with direct numerical computations in two steps for a prolate spheroid maneuvering in the longitudinal plane near the free surface. First, the hydrodynamic force and moment predicted by the model are compared with solutions from the panel code for sinusoidal motion in surge, heave, and pitch in calm water. Second, the hydrodynamic force and moment are investigated for cases where the spheroid maneuvers to approach the surface in calm water and in plane progressive waves. To conclude, a physically intuitive formulation of the Lagrangian nonlinear maneuvering and seakeeping model is presented for control applications and simulations.
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    An Approach for Computing Parameters for a Lagrangian Nonlinear Maneuvering and Seakeeping Model of Submerged Vessel Motion
    Jung, Seyong; Brizzolara, Stefano; Woolsey, Craig A. (IEEE, 2021-03)
    In this study, hydrodynamic forces on a submerged vessel maneuvering near a free surface are determined using a reformulated Lagrangian nonlinear maneuvering and seakeeping model derived using Lagrangian mechanics under ideal flow assumptions. A Lagrangian mechanics maneuvering model is first reformulated to simplify the computation of parameters; then, incident wave effects are incorporated into the reformulation; finally, the parameters are computed using a medium-fidelity time-domain potential-flow panel code. Predictions from the reformulated Lagrangian nonlinear maneuvering and seakeeping model, whose parameters are computed using the methods described here, are compared with direct numerical computations in two steps for a prolate spheroid maneuvering in the longitudinal plane near the free surface. First, the hydrodynamic force and moment predicted by the model are compared with solutions from the panel code for sinusoidal motion in surge, heave, and pitch in calm water. Second, the hydrodynamic force and moment are investigated for cases where the spheroid maneuvers to approach the surface in calm water and in plane progressive waves. To conclude, a physically intuitive formulation of the Lagrangian nonlinear maneuvering and seakeeping model is presented for control applications and simulations.
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    Parameter computation for a Lagrangian mechanical system model of a submerged vessel moving near a free surface
    Jung, Seyong; Brizzolara, Stefano; Woolsey, Craig A. (Elsevier, 2021-06)
    This paper describes the computation of parameters for a Lagrangian mechanical system model of a submerged vessel moving near an otherwise calm free surface using a medium-fidelity potential flow code. The software uses the boundary element method to solve for the flow potential on the body and the free surface. The model, a system of integro-differential equations involving functions of the velocity potential, is the “maneuvering” component of a Lagrangian nonlinear maneuvering and seakeeping model that was introduced in earlier work. Here, this nonlinear maneuvering model is reformulated and the potential flow software is modified to support parameter computations. Parameters are computed for a prolate spheroid moving parallel to a calm free surface at a constant forward speed. This motion induces a steady flow with respect to the body, which results in a steady surge force, heave force and pitch moment. These longitudinal forces and moment are computed using the reformulated Lagrangian nonlinear maneuvering model and the results are compared with basic panel code solutions for various depths and Froude numbers and for various computational parameter values.