Adrian Lungu

Numerical Breaking Waves around a Surface Piercing NACA 0012 Hydrofoil

The present study concerns the numerical simulation of the free surface flow around a surface piercing NACA 0012 hydrofoil. RANS equations and the realizable k‐e turbulence model are solved to describe the viscous free‐surface flow around hydrofoil, by using a VOF‐based technique of the Ansys Fluent software package. The computational solutions are compared with the experimental data measured at the Ship Hydrodynamics Division of the Research Centre, University of Galati for validation purposes.

Self‐Propulsion Simulation of a Tanker Hull

The paper proposes a numerical investigation based on RANS computations for solving the viscous flow around a self‐propelled tanker hull. A general numerical technique to estimate the propulsive performance is presented. For practical reasons, the technique couples a body forces method and a RANS‐based finite volume solver to account for the hull‐propeller interaction. This approach allows the quantification of the performance for a propeller working behind the ship hull, fully accounting for the effective wake conditions. The coupling of the methods therfore gives a combined numerical design and analysis tool. Numerical calculations and model tests have been compared to validate the technique used in the current work.

Numerical Simulation of the Turbulent Flow around a Strut Mounted on a Plate

The research describes the flow features around a protuberance mounted on a plate. It aims at establishing an appropriate method to further design the geometry of a fin mounted on the ship hull with the flow around the stern may be controlled. For that purpose, a numerical simulation aimed at describing the flow field around a NACA0012 hydrofoil mounted on a plate is presented. Several geometric configurations are taken into account, e.g. flat or curved plate, straight or inclined hydrofoil. RANS equations are solved to compute the solution around the juncture. Closure to the turbulence is done by using the Spalart‐Allmaras one‐equation model and the results are compared. A FVM technique is employed to solve the problem numerically. H‐C type grids are used for the PDE discretization.

Numerical Study of a 3‐D Juncture Flow

A numerical simulation aimed at describing the flow field is presented as an incipient attempt to develop a tool for the extraction of a fluctuating pressure field around appendages mounted on a plate. RANS equations are employed to compute the solution over a simpler case of a protuberance mounted on a flat plate. Closure to the turbulence is done by using the k‐ω SST two‐equation model. The primary conclusion is that pressure fluctuations on the appendage are the result of several mechanisms, including normal turbulent fluctuations, interactions between horseshoe vortices, and upstream and downstream separations and reattachments. A introspection in the flow structure is done by analysing the streamlines topology. The mechanisms are either local or more global in nature, and combine to generate the overall turbulent fluctuations on the appendage.

Numerical investigation of the flow around the KVLCC2 hull in static drift motion

By the use of CFD methods, the present research depicts the numerical investigation of the incident flow developed around the hull with or without rudder and/or propeller, in the presence of a given drift angle, an accurate image of the flow pattern developed in front of, at and behind the propeller plane, as well as before, along and behind the rudder, being depicted and precisely analyzed, for all considered cases. The numerical integration of the incompressible RANS equations stands for the accomplishment of the present study, the propeller being modeled by a lifting line approach.

Numerical Study of the Wake Field Produced by a Hull Retrofitted with Flow Control Devices

The aim of this study is to improve the ship wake through two retrofit solutions. Due to Reynolds effects, CFD is used to perform several numerical simulations at full scale. The computed results are compared and conclusions are drawn regarding the proposed appendages effect on the wake field.

The Numerical Study of Propeller Efficiency in Non‐Uniform Flow

Standing for a better unravel of the propulsion efficiency during maneuver, the present research offers a detailed insight of the intricate phenomena which are defining the non‐uniform turbulent flow developed around four major configurations: propeller in open water, propeller‐rudder in open water, hull‐propeller and hull‐propeller‐rudder. Based on the numerical integration of the incompressible Reynolds averaged Navier–Stokes equations (RANS hereafter), the current study overtakes the complex character of the flow developed, in the stern of the ship, as a result of the interactions that appear between hull, propeller and rudder.

Numerical Modeling of the Wave Breaking

Two and three dimensional numerical investigations of viscous incompressible free surface flows are presented. The Reynolds averaged Navier‐Stokes (RANS hereafter) equations are coupled with the continuity equation and solved by using a finite‐difference method (FDM hereafter). A boundary fitted coordinate system is employed thereupon deficiencies associated mainly with interpolation at the free‐surface that is still in wide are identified and addressed. Consequently, new expressions for boundary conditions at open frontiers are proposed. Third‐order upwind schemes in which the third derivative of the wave elevation is intentionally introduced are used to determine the location of the particles laying on the free surface. Numerical wave reflections at boundaries are avoided by using artificial wave dampers there.

Numerical Studies on Free Surface Flow around a Hydrofoil Mounted on a Plate

The research describes the free surface flow features around a surface piercing hydrofoil mounted on a plate. It aims at establishing an appropriate method to study the interference between the free surface deformations and juncture flow using the Fluent commercial software. For that purpose RANS equations are solved to compute the solution around the juncture. A surface capturing technique, VOF, is employed in order to locate the free‐surface. Closure to the turbulence is done by using the k‐e model and the results are compared. A FVM technique is employed to solve the problem numerically. H‐C type grids are used for the PDE discretization. Open channel flows are characterized by the dimensionless Froude number, based on the water height, and the influence over the juncture flow is investigated.

Numerical Investigation on Ship Podded Propulsion

The paper proposes a numerical investigation based on RANS computation for solving the viscous flow around a ship podded propulsion unit. A set of computations has been performed to better understand the influences exerted by different configurations on the wake structure in the propeller disk in the pushing type case. The RANS computation method is employed to evaluate the flow field structure around the podded propulsion units and the forces acting on it. Hydrodynamic design podded system has not, so far, been fully established in the propeller‐pod‐strut system. It is necessary to use a reliable procedure in the design of such propulsion systems to increase the propulsion efficiency. In an attempt to meet these needs, the present paper introduces a numerical procedure to analyze the hydrodynamic performance of the propeller and steering system using a combined lifting line and RANS methods.