VORLAX 2020: Making a Potential Flow Solver Great Again

2021 ◽  
Author(s):  
Tyler J. Souders ◽  
Timothy T. Takahashi
Keyword(s):  
Potential Flow ◽  
Flow Solver

scholarly journals Comparison Between Experiments and a Multibody Weakly Nonlinear Potential Flow Approach for Modeling of Marine Operations

2018 ◽  
Author(s):  
Pierre-Yves Wuillaume ◽  
Pierre Ferrant ◽  
Aurélien Babarit ◽  
François Rongère ◽  
Mattias Lynch ◽  
...  
Keyword(s):  
Potential Flow ◽  
Wave Structure ◽  
Body Motion ◽  
Dynamics Modeling ◽  
Flow Solver ◽  
Weakly Nonlinear ◽  
Validation Test ◽  
Nonlinear Potential ◽  
Set Up ◽  
Validation Tests

This paper presents validation tests for a new numerical tool for the numerical simulation of marine operations. It involves multibody dynamics modeling, wave-structure interactions with large amplitude body motion and cable’s dynamic modeling. Hydrodynamic loads are computed using the WS_CN weakly nonlinear potential flow solver, based on the weak-scatterer hypothesis. Large deformation of the wetted body surfaces can be taken into account. Firstly the ECN’s WS_CN solver capabilities are extended to multibody simulations. A first validation test is performed by comparing numerical results to the experimental data of [1]. Then, a second validation test is proposed. It consists in the ballasting operation of a spar. The experimental set-up is described.

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.

Studies on the optimization of stern hull form based on a potential flow solver

2005 ◽  
Vol 10 (2) ◽  
pp. 61-69 ◽  
Author(s):  
Kazuo Suzuki ◽  
Hisashi Kai ◽  
Shigetoshi Kashiwabara
Keyword(s):  
Potential Flow ◽  
Hull Form ◽  
Flow Solver

REEF3D::FNPF: A Flexible Fully Nonlinear Potential Flow Solver

2019 ◽  
Author(s):  
Hans Bihs ◽  
Weizhi Wang ◽  
Tobias Martin ◽  
Arun Kamath
Keyword(s):  
Wave Propagation ◽  
Free Surface ◽  
Boundary Conditions ◽  
Potential Flow ◽  
Surface Boundary ◽  
Flow Solver ◽  
Surface Boundary Conditions ◽  
Nonlinear Potential ◽  
Numerical Wave ◽  
Computational Resources

Abstract In situations where the calculation of ocean wave propagation and impact on offshore structures is required, fast numerical solvers are desired in order to find relevant wave events in a first step. After the identification of the relevant events, Computational Fluid Dynamics (CFD) based Numerical Wave Tanks (NWT) with an interface capturing two-phase flow approach can be used to resolve the complex wave structure interaction, including breaking wave kinematics. CFD models emphasize detail of the hydrodynamic physics, which makes them not the ideal candidate for the event identification due to the large computational resources involved. In the current paper a new numerical wave model is represented that solves the Laplace equation for the flow potential and the nonlinear kinematic and dynamics free surface boundary conditions. This approach requires reduced computational resources compared to CFD based NWTs. In contrast to existing approaches, the resulting fully nonlinear potential flow solver REEF3D::FNPF uses a σ-coordinate grid for the computations. Solid boundaries are incorporated through a ghost cell immersed boundary method. The free surface boundary conditions are discretized using fifth-order WENO finite difference methods and the third-order TVD Runge-Kutta scheme for time stepping. The Laplace equation for the potential is solved with Hypres stabilized bi-conjugated gradient solver preconditioned with geometric multi-grid. REEF3D::FNPF is fully parallelized following the domain decomposition strategy and the MPI communication protocol. The model is successfully tested for wave propagation benchmark cases for shallow water conditions with variable bottom as well as deep water.

scholarly journals Preliminary Parameter Characterization for Numerical Optimisation of Ducted Propellers

2019 ◽  
Vol 1 (2) ◽  
pp. Manuscript
Author(s):  
Jean-Marc Laurens ◽  
Margot Remaud ◽  
Pierre-Michel Guilcher
Keyword(s):  
Steady State ◽  
Potential Flow ◽  
Steady State Flow ◽  
Flow Solver ◽  
Flow Problems ◽  
Performance Predictions ◽  
Preliminary Study ◽  
Unsteady Problems ◽  
Numerical Optimisation ◽  
Ducted Propellers

In this paper, a preliminary parameter characterization for the numerical optimisation of ducted propellers was performed. The ENSTA Bretagne in-house solver used is based on the potential flow theory. Although the potential flow solver is able to solve unsteady problems, in this preliminary study only steady state flow problems are considered. Different parameters were analysed, such as the gap between the propeller tip and the inner duct surface as well as the propeller location in the duct tube. The analyses were carried out on a standard advance coefficient range. A quick study showed that a neutral NACA profile for the duct section could provide higher performance predictions than the classical accelerating Kort nozzle 19A.

On the Coupling of Incompressible SPH with a Finite Element Potential Flow Solver for Nonlinear Free-Surface Flows

2018 ◽  
Vol 28 (3) ◽  
pp. 248-254 ◽  
Author(s):  
Georgios Fourtakas ◽  
Peter Stansby ◽  
Benedict Rogers ◽  
Steven Lind ◽  
Shiqiang Yan ◽  
...  
Keyword(s):  
Finite Element ◽  
Free Surface ◽  
Potential Flow ◽  
Free Surface Flows ◽  
Surface Flows ◽  
Flow Solver ◽  
Incompressible Sph ◽  
Nonlinear Free Surface

Steep Wave Loads From Irregular Waves on an Offshore Wind Turbine Foundation: Computation and Experiment

2013 ◽  
Author(s):  
Bo Terp Paulsen ◽  
Henrik Bredmose ◽  
Harry B. Bingham ◽  
Signe Schløer
Keyword(s):  
Free Surface ◽  
Potential Flow ◽  
Surface Elevation ◽  
Irregular Waves ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Free Surface Elevation ◽  
Fully Nonlinear ◽  
Flow Solver ◽  
Nonlinear Potential

Two-dimensional irregular waves on a sloping bed and their impact on a bottom mounted circular cylinder is modeled by three different numerical methods and the results are validated against laboratory experiments. We here consider the performance of a linear-, a fully nonlinear potential flow solver and a fully nonlinear Navier-Stokes/VOF solver. The validation is carried out in terms of both the free surface elevation and the inline force. Special attention is paid to the ultimate load in case of a single wave event and the general ability of the numerical models to capture the higher harmonic forcing. The test case is representative for monopile foundations at intermediate water depths. The potential flow computations are carried out in a two-dimensional vertical plane and the inline force on the cylinder is evaluated by the Morison equation. The Navier-Stokes/VOF computations are carried out in three-dimensions and the force is obtained by spatial pressure integration over the wettet area of the cylinder. In terms of both the free surface elevation and the inline force, the linear potential flow model is shown to be of limited accuracy and large deviations are generally seen when compared to the experimental measurements. The fully nonlinear Navier-Stokes/VOF computations are accurately predicting both the free surface elevation and the inline force. However, the computational cost is high relative to the potential flow solvers. Despite the fact that the nonlinear potential flow model is carried out in two-dimensions it is shown to perform just as good as the three-dimensional Navier-Stokes/VOF solver. This is observed for both the free surface elevation and the inline force, where both the ultimate load and the higher harmonic forces are accurately predicted. This shows that for moderately steep irregular waves a Morison equation combined with a fully nonlinear two-dimensional potential flow solver can be a good approximation.

A Genetic Algorithm Approach to the Problem of Minimum Ship Wave Resistance

2002 ◽  
Vol 39 (03) ◽  
pp. 187-195
Author(s):  
Roko Dejhalla ◽  
Zoran Mrša ◽  
Senka Vukovic´
Keyword(s):  
Genetic Algorithm ◽  
Potential Flow ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Wave Resistance ◽  
Ship Hull ◽  
Point Of View ◽  
Flow Solver ◽  
Genetic Algorithm Approach

A genetic algorithm-based optimization method is proposed for an optimization of a ship hull from a hydrodynamic point of view. In the optimization procedure, the wave resistance has been selected as an objective function. The genetic algorithm is coupled with a computer program for solving the three-dimensional potential flow around a ship hull. The potential flow solver is based upon the well-known Dawson method. The optimization procedure has been applied to the Series 60 CB = 0.60 hull taken as a basis hull. The computational examples show the optimization ability of the proposed method.

Effect of Moonpool Shape and Dimensions on Drillship Operability

2018 ◽  
Author(s):  
Dimitris Chalkias ◽  
Jan Willem Krijger
Keyword(s):  
Environmental Conditions ◽  
Analytical Method ◽  
Potential Flow ◽  
Splash Zone ◽  
Regular Wave ◽  
Flow Solver ◽  
Specific Location ◽  
Optimization Study ◽  
Free Decay ◽  
Lower Chamber

All modern drillships are equipped with moonpools, through which drilling and other subsea operations are performed. The operability of the vessel, is the percentage of time that the vessel can perform a specific operation in a specific location not limited by environmental conditions. Specific operations such as lowering a BOP or X-tree through the splash zone, have strict operability criteria and often a drillship is waiting on weather to perform these operations. In this paper, the underwater shape of the moonpool of a drillship is varied and the operability of the vessel is calculated and compared to the original shape. Ten moonpool configurations are used for the study. The GustoMSC “Galene” moonpool shape is used which is comprised of an upper and a lower chamber. The lower chamber or cutout step dimensions such as length, breadth and height are the variables for this study. An analytical method originally proposed by Newman [1] and extended by Chalkias and Krijger [2] is used in this optimization study. The method is comprised of a potential flow radiation/diffraction solver, where the moonpool modes are accounted as additional separate generalized modes. In this way each mode can be damped separately. In order to calculate the damping factors for the moonpool modes used in the potential flow solver, free decay CFD calculations are performed and a P-Q analysis is applied on the resulting time-traces. Additional regular wave CFD calculations are performed for method validation purposes. The efficiency and ease of the proposed method is demonstrated by calculating the responses and operability of multiple shape variations in the frequency domain.

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