Dynamic overset grids in OpenFOAM with application to KCS self-propulsion and maneuvering

Multiscale tow-phase flow modeling of sheet and cloud cavitation

Computational fluid dynamics for ship hydrodynamics has made monumental progress over the last ten years, which is reaching the milestone of providing first-generation simulation-based design tools with vast capabilities for model- and full-scale simulations and optimization. This is due to the enabling technologies such as free surface tracking/capturing, turbulence modeling, 6 degree of freedom (DoF) motion prediction, dynamic overset grids, local/adaptive grid refinement, high performance computing, environmental modeling and optimization methods. Herein, various modeling, numerical methods, and high performance computing approaches for computational ship hydrodynamics are evaluated thereby providing a vision for the development of the next-generation high-fidelity simulation tools. Verification and validation procedures and their applications, including resistance and propulsion, seakeeping, maneuvering, and stability and capsizing, are reviewed. Issues, opportunities, and challenges for advancements in higher-fidelity two-phase flow are addressed. Fundamental studies for two-phase flows are also discussed. Conclusions and future directions are also provided.

Computational ship hydrodynamics: Nowadays and way forward

A versatile algorithm for the treatment of open boundary conditions in Smoothed particle hydrodynamics GPU models

Simulations of zigzag maneuvers for a container ship with direct moving rudder and propeller

Unsteady Reynolds averaged Navier–Stokes (URANS) computations of standard maneuvers are performed for a surface combatant at model and full scale. The computations are performed using CFDShip-Iowa v4, a free surface solver designed for 6DOF motions in free and semi-captive problems. Overset grids and a hierarchy of bodies allow the deflection of the rudders while the ship undergoes 6DOF motions. Two types of maneuvers are simulated: steady turn and zigzag. Simulations of steady turn at 35° rudder deflection and zigzag 20/20 maneuvers for Fr = 0.25 and 0.41 using constant RPM propulsion are benchmarked against experimental time histories of yaw, yaw rate and roll, and trajectories, and also compared against available integral variables. Differences between CFD and experiments are mostly within 10 % for both maneuvers, highly satisfactory given the degree of complexity of these computations. Simulations are performed also with waves, and with propulsion at either constant RPM or torque. 20/20 zigzag maneuvers are simulated at model and full scale for Fr = 0.41. The full scale case produces a thinner boundary layer profile compared to the model scale with different reaction times and handling needed for maneuvering. Results indicate that URANS computations of maneuvers are feasible, though issues regarding adequate modeling of propellers remain to be solved.

Turn and zigzag maneuvers of a surface combatant using a URANS approach with dynamic overset grids

The simulation of free surface bubbly flows using a two-fluid model remains a challenging problem in part due to the lack of a comprehensive air entrainment model that can predict the rate and location of air entrainment for a wide range of flows. In this study we derive a sub-grid model and implement it in a computational multiphase fluid dynamics (CMFD) framework to solve the Reynolds-averaged two-fluid equations. We assess the performance of our model in simulating bubbly flows underneath a plunging liquid jet and a hydraulic jump while varying the characteristic velocity. We compare the void fraction predictions with their experimental counterparts and conclude that the air entrainment model and the two-fluid modeling approach yield accurate results everywhere for the plunging jet and in the turbulent shear layer for the hydraulic jump. The inability of the proposed approach to recover the high void fraction in the roller region of the hydraulic jump is attributed to the failure of RaNS model to resol...

https://journals.sagepub.com/doi/pdf/10.1260/1757-482X.3.1.41

Mark C. Hyman

Papers

Turn and zigzag maneuvers of a surface combatant using a URANS approach with dynamic overset grids

A Comprehensive Sub-Grid Air Entrainment Model for RaNS Modeling of Free-Surface Bubbly Flows

Two-fluid modeling of bubbly flows around surface ships using a phenomenological subgrid air entrainment model

Numerical investigation of wave elevation and bottom pressure generated by a planing hull in finite-depth water

Three-dimensional flow around a submerged body in finite-depth water