MODEL- AND FULL-SCALE RANS SIMULATIONS FOR A DRIFT TANKER

2021 ◽  
Vol 159 (A2) ◽  
Author(s):  
J Yao
Keyword(s):  
Eddy Viscosity ◽  
Scale Effects ◽  
Grid Point ◽  
Computational Grid ◽  
Measured Data ◽  
Full Scale ◽  
Computational Time ◽  
Wall Function ◽  
Ship Hydrodynamics ◽  
Sst Model

The flow around a full-scale (FS) ship can be simulated by means of Reynolds-Averaged Naiver-Stokes (RANS) method, which provides a way to obtain more knowledge about scale effects on ship hydrodynamics. In this work, the viscous flow around a static drift tanker in full scale is simulated by using the RANS solver based on the open source platform OpenFOAM. The k - w SST model is employed to approximate the eddy viscosity. To reduce computational time, wall function approach is applied for the FS simulation. The flow around the ship in model scale is simulated as well, but without using any wall function, i.e., using Low-Reynolds number mode. In order to verify the computations, de- tailed studies on the computational grid including investigation of the sensitivity of computed forces to y+ (dimension- less distance of first grid point to wall) and grid dependency study are carried out. The computed forces are compared with available measured data. The scale effects are analysed and discussed by comparisons.

Model- and Full-Scale RANS Simulations for a Drift Tanker

2017 ◽  
Vol Vol 159 (A2) ◽  
Author(s):  
J Yao
Keyword(s):  
Scale Effect ◽  
Eddy Viscosity ◽  
Grid Point ◽  
Computational Grid ◽  
Measured Data ◽  
Full Scale ◽  
Computational Time ◽  
Wall Function ◽  
Ship Hydrodynamics ◽  
Sst Model

The flow around a full scale (FS) ship can be simulated by mean s of Reynolds Averaged Naiver Stokes (RANS) method, which provides a way to obtain more knowledge about scale effect s on ship hydrodynamics. In this work, the viscous flow around a static drift tanker in full scale is simulated by using the RANS solver based on the open source platform OpenFOAM. The 𝑘−𝜔 SST model is employed to approximate the eddy viscosity. To reduce computational time, wall function approach is applied for the FS simulation. The flow around the ship in model scale is simulated as well, but without using any wall function, i.e. using Low Reynolds number mode. In order to verify the computations, de-tailed studies on the computational grid including investigation of the sensitivity of computed forces to 𝑦+ (dimension-less distance of first grid point to wall) and grid dependency study are carried out. The computed forces are compared with available measured data The scale effect s are analysed and discussed by comparisons.

Scale effects and full-scale ship hydrodynamics: A review

2022 ◽  
Vol 245 ◽  
pp. 110496
Author(s):  
Momchil Terziev ◽  
Tahsin Tezdogan ◽  
Atilla Incecik
Keyword(s):  
Scale Effects ◽  
Full Scale ◽  
Ship Hydrodynamics

Evaluating an Indoor Daylight Illuminance Calculation Tool Against Full-Scale Measured Data

2006 ◽  
Vol 49 (3) ◽  
pp. 243-251 ◽  
Author(s):  
Danny H.W. Li ◽  
Gary H.W. Cheung ◽  
K. L. Cheung
Keyword(s):  
Measured Data ◽  
Full Scale

A Comparison of Several Strategies to Optimize a Ship’s Aft Body

2011 ◽  
Vol 27 (04) ◽  
pp. 202-211
Author(s):  
Auke van der Ploeg
Keyword(s):  
Viscous Flow ◽  
Scale Effects ◽  
Full Scale ◽  
Ship Hull ◽  
Hull Form ◽  
Wake Field ◽  
Hull Forms ◽  
Definition Of

This paper describes a procedure to optimize ship hull forms, based on double body viscous flow computations with PARNASSOS. A flexible and effective definition of parametric hull form variations is used, based on interpolation between basis hull forms. One of the object functions is an estimate of the required power. In this paper we will focus on how to improve this estimate, by using the B-series of propellers. Results of systematic variations applied to the VIRTUE tanker together with scale effects in the computed trends will be discussed. In addition, we will demonstrate how the techniques discussed in this paper can be used to design a model that has a wake field that strongly resembles the wake of a given containership ship at full scale.

scholarly journals Improvement of anisotropic porosity models with a merging technique

2018 ◽  
Vol 40 ◽  
pp. 06023
Author(s):  
Martin Bruwier ◽  
Pierre Archambeau ◽  
Sébastien Erpicum ◽  
Michel Pirotton ◽  
Benjamin Dewals
Keyword(s):  
Shallow Water ◽  
Flow Characteristics ◽  
Threshold Value ◽  
Computational Grid ◽  
Computational Time ◽  
Time Step ◽  
Shallow Water Models ◽  
The Cost ◽  
The Impact ◽  
Porosity Model

Anisotropic porosity shallow-water models are used to take into account detailed topographic information through porosity parameters multiplying the various terms of the shallow-water equations. A storage porosity is assigned to each cell to reflect the void fraction in the cell and a conveyance porosity is used at each edge to reproduce the impact of subgrid obstacles on the flux terms. To guaranty the numerical stability, the time step depends on the value of the porosity parameters. This may hamper severely the computational efficiency in the presence of cells with low values of storage porosity. Cartesian grids are particularly sensitive to such a case since the meshing stems directly from the choice of the grid size. In this paper, this problem is addressed by using an original merging technique consisting in merging cells with a storage porosity lower than a threshold value with neighbouring cells. The model was tested for modelling a prismatic channel with different orientations between the Cartesian computational grid and the channel direction. The results show that the standard anisotropic porosity model (without merging) improves the reproduction of the flow characteristics; but at the cost of a significantly higher computational time. In contrast, the computational time is drastically reduced and the accuracy preserved when the merging technique is used with the porosity model.

Grid requirements for LES of ship hydrodynamics in model and full scale

2017 ◽  
Vol 143 ◽  
pp. 259-268 ◽  
Author(s):  
Mattias Liefvendahl ◽  
Christer Fureby
Keyword(s):  
Full Scale ◽  
Ship Hydrodynamics

Model-Scale and Full-Scale CFD Calculations for Current Loads on Semi-Submersible

2011 ◽  
Author(s):  
Arjen Koop ◽  
Alexei Bereznitski
Keyword(s):  
Wind Tunnel ◽  
Scale Effects ◽  
Full Scale ◽  
Grid Resolution ◽  
Wind Tunnel Experiments ◽  
Force Coefficients ◽  
Model Scale ◽  
Coarse Grids

In this paper results of CFD calculations with the MARIN in-house code ReFRESCO are presented for the JBF-14000 Semi-Submersible designed by Huisman Equipment BV. The objective of the CFD calculations is to investigate the applicability, the costs and the accuracy of CFD to obtain the current coefficients of a semi-submersible for all headings. Furthermore, full scale CFD calculations are carried out to investigate possible scale effects on the current coefficients. An extensive verification study has been carried for the model-scale current loads on a semi-submersible using 10 different grids of different grid type for 3 different headings, i.e. 180, 150 and 90 degrees. These headings represent the main different flow regions around the semi-submersible. The CFD results are compared with the results from wind tunnel experiments and tests in the Offshore Basin for a range of current headings. The results for the force coefficients are not very dependent on grid resolution and grid type. The largest differences found are less than 10% and these are obtained for CX results for 180 degrees. For the results obtained on the same grid type the results change less than 4% when the grid is refined. These verification results give good confidence in the CFD results. For the angles with larger forces, i.e. the range [180:130] for CX and the range [150:90] for CY the CFD results are within 12% or better from the experiments. Full-scale force coefficients are calculated using 5 subsequently refined grids for three different headings, i.e. 180, 150 and 90 degrees. Scale effects should only be determined when the effect of grid refining is investigated. The trend of the force coefficients when refining the grid, can be different for model-scale and full-scale. The use of coarse grids can lead to misleading conclusions. On average the full-scale values are approximately 15–20% lower than for model-scale. However, larger differences for a number of angles do exist.

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