A Study on the Estimation Method of the Form Factor for a Full-Scale Ship

Lee, Young-Gill; Ha, Yoon-Jin; Lee, Seunng-Hee; Kim, Sang Hyun

doi:10.21278/brod69105

Cited by 12 publications

(5 citation statements)

References 8 publications

(27 reference statements)

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“…Recently, there are many computational studies with GEOSIM series to investigate the hydrodynamic performance of ships. 17,18 Telfer proposed originally the GEOSIM based extrapolation method to estimate the ship drag at full-scale by experiments. Although it was known that the method gives the most accurate results, it had very limited usage before due to high experimental costs.…”

Section: Computational Resultsmentioning

confidence: 99%

“…But now it is also a topic of the computational studies. Lee et al 17 have used a GEOSIM series for different benchmark hull geometries to extrapolate the results at model scales to those at full-scale with a logarithmic Reynolds number-based procedure. Terziev et al 18 have performed double body and multiphase analyses of a GEOSIM model family of KCS (KRISO Container Ship) hull including full-scale ship and drag force was evaluated in terms of Re numbers.…”

Section: Introduction and Literature Surveymentioning

confidence: 99%

See 1 more Smart Citation

Prediction of drag and lift forces of a high-speed vessel at full scale by CFD-based GEOSIM method

Can

Bal

2022

Proceedings of the Institution of Mechanical Engineers, Part M:

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In this study, it was aimed to obtain an accurate extrapolation method to compute lift and drag forces of high-speed vessels at full-scale by using CFD (Computational Fluid Dynamics) based GEOSIM (GEOmetrically SIMilar) method which is valid for both fully planing and semi-planing regimes. Athena R/V 5365 bare hull form with a skeg which is a semi-displacement type of high-speed vessel was selected with a model family for hydrodynamic analyses under captive and free to sinkage/trim conditions. Total drag and lift forces have been computed for a generated GEOSIM family of this form at three different model scales and full-scale for Fr = 0.8 by an unsteady RANS (Reynolds Averaged Navier–Stokes) solver. k–ε turbulence model was used to simulate the turbulent flow around the hulls, and both DFBI (Dynamic Fluid Body Interaction) and overset mesh technique were carried out to model the heave and pitch motions under free to sinkage/trim condition. The computational results of the model family were used to get “drag-lift ratio curve” for Athena hull at a fixed Fr number and so the corresponding results at full scale were predicted by extrapolating those of model scales in the form of a non-dimensional ratios of drag-lift forces. Then the extrapolated full-scale results calculated by modified GEOSIM method were compared with those of full-scale CFD and obtained by Froude extrapolation technique. The modified GEOSIM method has been found to be successful to compute the main forces (lift and drag) acting on high-speed vessels as a single coefficient at full scale. The method also works accurately both under fully and semi-planing conditions.

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Section: Computational Resultsmentioning

confidence: 99%

Section: Introduction and Literature Surveymentioning

confidence: 99%

Prediction of drag and lift forces of a high-speed vessel at full scale by CFD-based GEOSIM method

Can

Bal

2022

Proceedings of the Institution of Mechanical Engineers, Part M:

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show abstract

“…The form factor of a ship during model tests and the same value can be used when extrapolating the results to full scale. On the other hand, previous studies showed that the form factors vary with the Reynolds number and many attempts have been made to remedy the problem [9].…”

Section: Resistance and Ehp Predictionmentioning

confidence: 99%

Ehp Value of Mini LNG Ship With Form Factor From Prohaska and Irls Method Using Ship Resistance Testing Data

Widodo,

Santoso,

Erwandi

et al. 2023

Jurnal Teknologi

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The ship model test was believed to be one of the effective methods for figuring out the boundaries and reliability of the ship's horsepower. The ship's form factor determines a full-scale ship's effective horsepower. Determination of the form factor value can be done experimentally through the Prohaska method. The new method proposed in this study is employed the regression Iteratively Reweighted Least Squares (IRLS) method by utilizing the principle dimension of the ship, such as LWL, B, CB, CP, CM, WSA, T, ∆. etc. The Indonesian Hydrodynamics Laboratory has a database of ships with various principle dimensions which have undergone the towing model test. Through the database, the form factor can be predicted with the IRLS method. The method is then verified and validated with the Prohaska method. The result shows a good agreement with the Prohaska method. The obtained results from the IRLS method also show that the EHP & Resistance calculations are identical with old fashion Prohaska methods. The residual bias factor established by the IRLS method was verified in comparison to the value of the form factor generated by the Prohaska method. Comparison between the two methods results in a small error.

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“…Still, the literature on this subject suggests that incorporating multiple hull forms is not advantageous. For instance, García-Gómez (2000), Min and Kang, (2010), and Lee et al (2018) showed scattering in results produced by different hull forms, even when considering non-dimensional quantities, such as the form factor. Although we are by no means insured against the same outcome, it is maintained that a more in-depth study is possible considering a single hull form.…”

Section: Ship Geometry and Conditionsmentioning

confidence: 99%

“…Therefore, the troubles of the naval architect do not end once the experiment has run its course. We may only keep the ratio of inertial and viscous forces (the Reynolds number -Re), or the ratio of gravitational and inertial forces (the Froude number -Fr) the same between model and ship (Lee et al, 2018). Extrapolation procedures have been devised to keep these ratios, the earliest by William Froude in the 1870s (Molland et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A geosim analysis of ship resistance decomposition and scale effects with the aid of CFD

Terziev

Tezdogan

Incecik

2019

Applied Ocean Research

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Historically, the prediction ship resistance has received its fair share of attention by the scientific community. Yet, a robust scaling law still lacks, leaving testing facilities to rely on experience-based approaches and large datasets accumulated from years of operation. Academia's concern regarding this has not led to an extrapolation procedure, capable of bearing scrutiny adequately. One way to circumvent what has become the bane of the study of ship resistance is to perform Reynolds averaged Navier-Stokes (RANS) simulations directly in full-scale. The rapid advent of such methods has meant that confidence levels in predictions achieved by RANS simulations are low. This paper explores and demonstrates scale effects on the constituent components of ship resistance by performing a geosim analysis using a Computational Fluid Dynamics approach. Emphasis is placed on challenging the assumptions imposed as part of the currently accepted ship resistance extrapolation procedure. Our results suggest that a high degree of uncertainty exists in the calculated full-scale resistance depending on the approach taken towards its evaluation. In particular, scale effects are demonstrated in wave resistance, while free surface effects are palpable in the frictional resistance.

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A Study on the Estimation Method of the Form Factor for a Full-Scale Ship

Cited by 12 publications

References 8 publications

Prediction of drag and lift forces of a high-speed vessel at full scale by CFD-based GEOSIM method

Prediction of drag and lift forces of a high-speed vessel at full scale by CFD-based GEOSIM method

Ehp Value of Mini LNG Ship With Form Factor From Prohaska and Irls Method Using Ship Resistance Testing Data

A geosim analysis of ship resistance decomposition and scale effects with the aid of CFD

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