Surface Ship Total Resistance Prediction Based on a Nonlinear Free Surface Potential Flow Solver and a Reynolds-Averaged Navier-Stokes Viscous Correction

2007 ◽  
Vol 51 (01) ◽  
pp. 47-64
Author(s):  
James C. Huan ◽  
Thomas T. Huang
Keyword(s):  
Free Surface ◽  
Surface Potential ◽  
Potential Flow ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Total Resistance ◽  
Flow Solver ◽  
Resistance Prediction ◽  
Nonlinear Free Surface

A fast turnaround and an accurate computational fluid dynamics (CFD) approach for ship total resistance prediction is developed. The approach consists of a nonlinear free surface potential flow solver (PShip code) with a wet-or-dry transom stern model, and a Reynolds-averaged Navier-Stokes (RANS) equation solver that solves viscous free surface flow with a prescribed free surface given from the PShip. The prescribed free surface RANS predicts a viscous correction to the pressure resistance (viscous form) and viscous flow field around the hull. The viscous free surface flow solved this way avoids the time-consuming RANS iterations to resolve the free surface profile. The method, however, requires employing a flow characteristic-based nonreflecting boundary condition at the free surface. The approach can predict the components of ship resistance, the associated wave profile around the hull, and the sinkage and trim of the ship. Validation of the approach is presented with Wigley, Series 60 (CB = 0.6), and NSWCCD Model 5415 hulls. An overall accuracy of ±2% for ship total resistance prediction is achieved. The approach is applied to evaluating the effects of a stern flap on a DD 968 model on ship performance. An empirical viscous form resistance formula is also devised for a quick ship total resistance estimate.

scholarly journals WAVE MOTION NEAR A BREAKWATER ROUNDHEAD

2012 ◽  
Vol 1 (33) ◽  
pp. 71
Author(s):  
Takahide Honda ◽  
Peter Wellens ◽  
Marcel Van Gent
Keyword(s):  
Free Surface ◽  
Wave Motion ◽  
Flow Model ◽  
Stokes Equations ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Physical Model Tests

COMFLOW is a general 3D free-surface flow solver. The numerical method is based on the Navier-Stokes equations in a porous medium, with additional force terms to represent the (turbulent) interaction of the flow with the medium. The free surface is displaced by means of the Volume-Of-Fluid method. The main objective in this paper is to validate the permeable flow model in 3D. Tailor-made physical model tests were performed for this purpose. In the experiment surface elevations are measured inside and around a permeable structure with 18 wave gauges in total. The measurements are represented well by the simulation results.

scholarly journals 3D SIMULATION OF WAVE INTERACTION WITH PERMEABLE STRUCTURES

2011 ◽  
Vol 1 (32) ◽  
pp. 28 ◽  
Author(s):  
Peter Wellens ◽  
M.J.A. Borsboom ◽  
M.R.A. Van Gent
Keyword(s):  
Free Surface ◽  
Reflection Coefficient ◽  
Flow Model ◽  
Wave Interaction ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Flow Solver ◽  
Simulation Results ◽  
Rubble Mound Breakwaters

COMFLOW is a general 3D free-surface flow solver. The main objective in this paper is to extend the solver with a permeable flow model to simulate wave interaction with rubble-mound breakwaters. The extended Navier-Stokes equations for permeable flow are presented and we show the discretization of these equations as they are implemented in COMFLOW. An analytical solution for the reflection coefficient of a permeable structure is derived and the numerical model is compared to the solution. In addition, a validation study has been performed, in which we compare the numerical results with an experiment. In the experiment, pressures and surface elevations are measured inside a permeable structure. The measurements are represented well by the simulation results. At the end, a 3D application of the model is shown.

Unstructured Grid Based Reynolds-Averaged Navier-Stokes Method for Liquid Tank Sloshing

2005 ◽  
Vol 127 (3) ◽  
pp. 572-582 ◽  
Author(s):  
Shin Hyung Rhee
Keyword(s):  
Free Surface ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Navier Stokes ◽  
Governing Equations ◽  
Reconstruction Scheme ◽  
Geometric Reconstruction ◽  
Membrane Type ◽  
Tank Sloshing ◽  
Good Agreement

The present study is concerned with liquid tank sloshing at low filling level conditions. The volume of fluid method implemented in a Navier–Stokes computational fluid dynamics code is employed to handle the free-surface flow of liquid sloshing. The geometric reconstruction scheme for the interface representation is employed to ensure sharpness at the free surface. The governing equations are discretized by second order accurate schemes on unstructured grids. Several different computational approaches are verified and numerical uncertainties are assessed. The computational results are validated against existing experimental data, showing good agreement. The capability is demonstrated for a generic membrane-type liquefied natural gas carrier tank with a simplified pump tower inside. The validation results suggest that the present computational approach is both easy to apply and accurate enough for more realistic problems.

Nonlinear free-surface flow due to an impulsively started submerged point sink

1998 ◽  
Vol 364 ◽  
pp. 325-347 ◽  
Author(s):  
MING XUE ◽  
DICK K. P. YUE
Keyword(s):  
Free Surface ◽  
Steady State ◽  
Numerical Study ◽  
Free Surface Flow ◽  
Small Time ◽  
Surface Flow ◽  
Boundary Integral ◽  
Critical Regime ◽  
Gravitational Acceleration ◽  
Nonlinear Free Surface

The unsteady fully nonlinear free-surface flow due to an impulsively started submerged point sink is studied in the context of incompressible potential flow. For a fixed (initial) submergence h of the point sink in otherwise unbounded fluid, the problem is governed by a single non-dimensional physical parameter, the Froude number, [Fscr ]≡Q/4π(gh5)1/2, where Q is the (constant) volume flux rate and g the gravitational acceleration. We assume axisymmetry and perform a numerical study using a mixed-Eulerian–Lagrangian boundary-integral-equation scheme. We conduct systematic simulations varying the parameter [Fscr ] to obtain a complete quantification of the solution of the problem. Depending on [Fscr ], there are three distinct flow regimes: (i) [Fscr ]<[Fscr ]1≈0.1924 – a ‘sub-critical’ regime marked by a damped wave-like behaviour of the free surface which reaches an asymptotic steady state; (ii) [Fscr ]1<[Fscr ]<[Fscr ]2≈0.1930 – the ‘trans-critical’ regime characterized by a reversal of the downward motion of the free surface above the sink, eventually developing into a sharp upward jet; (iii) [Fscr ]>[Fscr ]2 – a ‘super-critical’ regime marked by the cusp-like collapse of the free surface towards the sink. Mechanisms behind such flow behaviour are discussed and hydrodynamic quantities such as pressure, power and force are obtained in each case. This investigation resolves the question of validity of a steady-state assumption for this problem and also shows that a small-time expansion may be inadequate for predicting the eventual behaviour of the flow.

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