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Defining Physics

In this simulation, we prescribe the Self-Propelled as propulsion option. Once the mesh for the domain is created using the Marine Template Mesher, the Marine model is automatically added to the Model Panel. The Flow module along with the settings for Multiphase and Turbulence is also enabled. The physics and conditions are specified in the Marine model as follows.

  1. Select the Marine model in the Model Panel.
  2. Select Pitch & Heave for the Dynamic Option drop down list in the Properties Panel > Model Tab.
  3. Select Self Propelled for the Propulsion Option drop-down list, with the following value definitions.
  • Projected Max Velocity: 12.861 m/s.
  • Propulsion Source: Propeller Model.
  • Enter 1 for Propulsion ID.
  • Enter 7.499, -0.85, -0.534 under the Position and 0.997, 0, -0.0722 under the Direction.
  • Select Hough-Ordway Model under Propeller Model.
  • Enter 0.5 m, 0.1 m and 0.25 m as Propeller Diameter, Hub Diameter and Hub Thickness, respectively.
  • Select Right-handed for the Propeller Direction and prpm1 for the Propeller RPM.
  • Enter kt1 for the Kt Curve and kq1 for the Kq Curve.
  • Click Edit Expression icon under Coordinates to open the Expression Editor dialog box.
  • Copy and paste the expressions written under Description drop-down list for Local Expressions, see Figure 8.68.
    • ClosedDescription

     

    #====================================================

    prpm1 = 1500

    kt1 = table(kt1.txt, marine.prop_J1)

    kq1 = table(kq1.txt, marine.prop_J1)

    plot.J_prop1 = marine.prop_J1

    plot.Kt_prop1 = kt1

    plot.Kq_prop1 = kq1

    plot.Eta_prop1 = marine.prop_J1 * kt1 / (2 * pi * kq1)

    prop1_diameter = 0.5

    plot.Thrust_prop1 = marine.prop_T1

    #plot.Thrust_prop1: [N]

    plot.Torque_prop1 = marine.prop_torque1

    #plot.Torque_prop1: [N-m]

    plot.Power_prop1 = marine.prop_power1

    #plot.Power_prop1: [W]

  • Ensure to include the table for Kt Curve (thrust coefficient as a function of advance coefficient) and Kq Curve (torque coefficient as a function of advance coefficient) in the working directory of the project. Incase of unavailability of the above tables, ensure to copy the following files from the tutorial folder into the working directory.

  • Enter 6000 kg and 27563.122 kg∙m2 for the Body Mass and Moment of Inertia respectively.

  • Enter the parameters for the extended Fluid Property list as follows.

    • Water Density: 1025.9 kg/m3

    • Water Viscosity: 0.001219 Pa.s

    • Air Density: 1.23 kg/m3

    • Air Viscosity: 1.81e-05 Pa.s

    • The parameters Hull Type, Analysis Type, Forward Direction, Up Direction, Center of Gravity, Waterline Position are preset from values given in the Marine Template Mesher and are displayed in blue color as shown in Figure 8.68.

    Figure 8.68 - Defining Physics

     

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