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Osman Turan - One of the best experts on this subject based on the ideXlab platform.

  • validation of the cfd approach for modelling roughness effect on Ship Resistance
    Ocean Engineering, 2020
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Abstract Recently, there have been active efforts to investigate the effect of hull roughness on Ship Resistance using Computational Fluid Dynamics (CFD). Although, several studies demonstrated that the roughness modelling in the CFD simulations can precisely predict the increase in frictional Resistance due to the surface roughness, the experimental validations have been made only for flat plates which have zero pressure gradient. This means that the validations cannot necessarily guarantee the validity of this method for other Ship Resistance components besides the frictional Resistance. Therefore, it is worth demonstrating the validity of the roughness modelling in CFD on the total Resistance of a 3D hull. In this study, CFD models of a towed flat plate and a KRISO Container Ship (KCS) model were developed. In order to simulate the roughness effect in the turbulent boundary layer, a previously determined roughness function of a sand-grain surface was employed in the wall-function of the CFD model. Then the result of the CFD simulations was compared with the experimental data. The result showed a good agreement suggesting that the CFD approach can precisely predict the roughness effect on the total Resistance of the 3D hull. Finally, the roughness effects on the individual Ship Resistance components were investigated.

  • Experimental and theoretical study of the effect of hull roughness on Ship Resistance
    Journal of Ship Research, 2020
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Hull roughness increases Ship frictional Resistance and thus results in economic and environmental penalties. Its effect has been prevalently predicted using the similarity law scaling procedure, presented by Granville (1958; 1978). However, this method has not yet been validated with experimental data using a model Ship. This paper presents an experimental investigation into the effect of roughness on Ship Resistance and provides a validation of the similarity law scaling, by using tank testing of a flat plate and a model Ship. Both the plate and the Ship were tested in smooth and rough surface conditions, respectively. For the rough surface conditions, sand grit (aluminium oxide abrasive powder) was applied on the surfaces of the flat plate and the Ship model. The roughness functions of the rough surface were derived by using the results obtained from the flat plate tests. Using the roughness function and the flat plate towing test, the frictional Resistance was extrapolated to the length of the model Ship following the similarity law scaling procedure. The total Resistance of the rough Ship model was first predicted using the extrapolated frictional Resistance and the result of the smooth Ship model, and then compared with the results from the rough Ship model. The predicted total Resistance coefficients for the rough Ship model showed good agreement with the measured total Resistance coefficient of the rough Ship model; thus proving the validity of using Granville’s similarity law scaling to extrapolate the roughness effect on Ship Resistance.

  • Does the barnacle settlement pattern affect Ship Resistance and powering
    Applied Ocean Research, 2020
    Co-Authors: Dogancan Uzun, Yigit Kemal Demirel, Refik Ozyurt, Osman Turan
    Abstract:

    Abstract Predictions of increases in Ship frictional Resistance and powering were made for a range of barnacle fouling conditions. A series of towing tests were conducted using flat plates systematically covered with 3D printed barnacle tiles. The tests were set up to investigate the effect of barnacle settlement on the Resistance and effective power of the Ship. Therefore, a chaotic settlement which is called natural settlement, was designed to represent real barnacle settlement in nature. An extensive comparison was made between this natural settlement and the settlement that was designed in accordance with the standards. The drag coefficients and roughness functions values were determined and full-scale Ship Resistance and powering were estimated for six different Ships at their cruise speed by using boundary layer similarity law. In addition, decreases in cruising speed due to barnacle fouling at fixed effective power were estimated as part of the case studies. The results indicate that settlement pattern caused up to ~10.5% difference in frictional Resistance and ~6.7% difference in powering at cruise speeds whereas this settlement pattern caused up to ~20.5% speed reduction at fixed effective power.

  • Time-dependent biofouling growth model for predicting the effects of biofouling on Ship Resistance and powering
    Ocean Engineering, 2019
    Co-Authors: Dogancan Uzun, Yigit Kemal Demirel, Andrea Coraddu, Osman Turan
    Abstract:

    Abstract This paper presents a time-dependent biofouling growth model which enables prediction of the effect of biofouling on Ship Resistance and powering for day-to-day evaluation. Initially, antifouling coating tests data were employed in the model to predict coating performance over time by considering the Ship operating profile and Shipping route. Based on the equivalent sand roughness heights found in literature, time-dependent biofouling growth predictions were turned into equivalent sand roughness heights. Then, the provided roughness functions for different surface conditions as well as the predicted equivalent sand roughness heights were employed in Granville's similarity law scaling to investigate the effect of roughness on full-scale Ship Resistance. Then, the model was tested through one-year long operation data of a 176 m long tanker measured by on-board systems to validate the model. Percentage increase in frictional Resistance of the 176 m long tanker was predicted to be ~32%. Results were compared and validated using real data. Secondly, a case study was performed using noon-report data for 3-years operation of a 258 m long crude-oil carrier. Increase in effective power of the Ship was predicted to be ~25%. Finally, the predictions were compared to Ship performance reports that were provided by the Ship operator.

  • Validation of the CFD approach for modelling roughness effect on Ship Resistance
    2019
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Recently, there have been active efforts to investigate the effect of hull roughness on Ship Resistance using Computational Fluid Dynamics (CFD). Although, several studies demonstrated that the roughness modelling in the CFD simulations can precisely predict the increase in frictional Resistance due to the surface roughness, the experimental validations have been made only for flat plates which have zero pressure gradient. This means that the validations cannot necessarily guarantee the validity of this method for other Ship Resistance components besides the frictional Resistance. Therefore, it is worth to demonstrate the validity of the roughness modelling in CFD on the total Resistance of a 3D hull. In this study, CFD models of a towed flat plate and a KRISO Container Ship (KCS) model were developed. In order to simulate the roughness effect in the turbulent boundary layer, a previously determined roughness function of a sand-grain surface was employed in the wall-function of the CFD model. Then the result of the CFD simulations was compared with the experimental data. The result showed a good agreement suggesting that the CFD approach can precisely predict the roughness effect on the total Resistance of the 3D hull. Finally, the roughness effects on the individual Ship Resistance components were investigated.

Yigit Kemal Demirel - One of the best experts on this subject based on the ideXlab platform.

  • Scale effect on Ship Resistance components and form factor
    Ocean Engineering, 2020
    Co-Authors: Ali Dogrul, Soonseok Song, Yigit Kemal Demirel
    Abstract:

    Abstract To design eco-friendly Ships, the hydrodynamic behaviour of the hull has to be estimated precisely. The first and foremost one is the Ship Resistance, which is closely related to the energy efficiency of the Ship. Different extrapolation methods, based on different assumptions, have been used to predict the full-scale Ship Resistance from model-scale experiments. In this manner, it is important to understand the scale effect on the individual Ship Resistance components. In this study, URANS CFD simulations of KCS and KVLCC2 were conducted at different scales. The total Resistance components were decomposed into the individual Resistance components to investigate the scale effects. The simulation results were compared with full-scale Resistance predictions using different extrapolation methods and the rationale of the different compliances between them was investigated. Finally, the hydrodynamic characteristics in different scales were examined.

  • validation of the cfd approach for modelling roughness effect on Ship Resistance
    Ocean Engineering, 2020
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Abstract Recently, there have been active efforts to investigate the effect of hull roughness on Ship Resistance using Computational Fluid Dynamics (CFD). Although, several studies demonstrated that the roughness modelling in the CFD simulations can precisely predict the increase in frictional Resistance due to the surface roughness, the experimental validations have been made only for flat plates which have zero pressure gradient. This means that the validations cannot necessarily guarantee the validity of this method for other Ship Resistance components besides the frictional Resistance. Therefore, it is worth demonstrating the validity of the roughness modelling in CFD on the total Resistance of a 3D hull. In this study, CFD models of a towed flat plate and a KRISO Container Ship (KCS) model were developed. In order to simulate the roughness effect in the turbulent boundary layer, a previously determined roughness function of a sand-grain surface was employed in the wall-function of the CFD model. Then the result of the CFD simulations was compared with the experimental data. The result showed a good agreement suggesting that the CFD approach can precisely predict the roughness effect on the total Resistance of the 3D hull. Finally, the roughness effects on the individual Ship Resistance components were investigated.

  • Experimental and theoretical study of the effect of hull roughness on Ship Resistance
    Journal of Ship Research, 2020
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Hull roughness increases Ship frictional Resistance and thus results in economic and environmental penalties. Its effect has been prevalently predicted using the similarity law scaling procedure, presented by Granville (1958; 1978). However, this method has not yet been validated with experimental data using a model Ship. This paper presents an experimental investigation into the effect of roughness on Ship Resistance and provides a validation of the similarity law scaling, by using tank testing of a flat plate and a model Ship. Both the plate and the Ship were tested in smooth and rough surface conditions, respectively. For the rough surface conditions, sand grit (aluminium oxide abrasive powder) was applied on the surfaces of the flat plate and the Ship model. The roughness functions of the rough surface were derived by using the results obtained from the flat plate tests. Using the roughness function and the flat plate towing test, the frictional Resistance was extrapolated to the length of the model Ship following the similarity law scaling procedure. The total Resistance of the rough Ship model was first predicted using the extrapolated frictional Resistance and the result of the smooth Ship model, and then compared with the results from the rough Ship model. The predicted total Resistance coefficients for the rough Ship model showed good agreement with the measured total Resistance coefficient of the rough Ship model; thus proving the validity of using Granville’s similarity law scaling to extrapolate the roughness effect on Ship Resistance.

  • Does the barnacle settlement pattern affect Ship Resistance and powering
    Applied Ocean Research, 2020
    Co-Authors: Dogancan Uzun, Yigit Kemal Demirel, Refik Ozyurt, Osman Turan
    Abstract:

    Abstract Predictions of increases in Ship frictional Resistance and powering were made for a range of barnacle fouling conditions. A series of towing tests were conducted using flat plates systematically covered with 3D printed barnacle tiles. The tests were set up to investigate the effect of barnacle settlement on the Resistance and effective power of the Ship. Therefore, a chaotic settlement which is called natural settlement, was designed to represent real barnacle settlement in nature. An extensive comparison was made between this natural settlement and the settlement that was designed in accordance with the standards. The drag coefficients and roughness functions values were determined and full-scale Ship Resistance and powering were estimated for six different Ships at their cruise speed by using boundary layer similarity law. In addition, decreases in cruising speed due to barnacle fouling at fixed effective power were estimated as part of the case studies. The results indicate that settlement pattern caused up to ~10.5% difference in frictional Resistance and ~6.7% difference in powering at cruise speeds whereas this settlement pattern caused up to ~20.5% speed reduction at fixed effective power.

  • Time-dependent biofouling growth model for predicting the effects of biofouling on Ship Resistance and powering
    Ocean Engineering, 2019
    Co-Authors: Dogancan Uzun, Yigit Kemal Demirel, Andrea Coraddu, Osman Turan
    Abstract:

    Abstract This paper presents a time-dependent biofouling growth model which enables prediction of the effect of biofouling on Ship Resistance and powering for day-to-day evaluation. Initially, antifouling coating tests data were employed in the model to predict coating performance over time by considering the Ship operating profile and Shipping route. Based on the equivalent sand roughness heights found in literature, time-dependent biofouling growth predictions were turned into equivalent sand roughness heights. Then, the provided roughness functions for different surface conditions as well as the predicted equivalent sand roughness heights were employed in Granville's similarity law scaling to investigate the effect of roughness on full-scale Ship Resistance. Then, the model was tested through one-year long operation data of a 176 m long tanker measured by on-board systems to validate the model. Percentage increase in frictional Resistance of the 176 m long tanker was predicted to be ~32%. Results were compared and validated using real data. Secondly, a case study was performed using noon-report data for 3-years operation of a 258 m long crude-oil carrier. Increase in effective power of the Ship was predicted to be ~25%. Finally, the predictions were compared to Ship performance reports that were provided by the Ship operator.

Atilla Incecik - One of the best experts on this subject based on the ideXlab platform.

  • A geosim analysis of Ship Resistance decomposition and scale effects with the aid of CFD
    Applied Ocean Research, 2019
    Co-Authors: Momchil Terziev, Tahsin Tezdogan, Atilla Incecik
    Abstract:

    Abstract 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.

  • predicting the effect of biofouling on Ship Resistance using cfd
    Applied Ocean Research, 2017
    Co-Authors: Yigit Kemal Demirel, Osman Turan, Atilla Incecik
    Abstract:

    Abstract This paper proposes a Computational Fluid Dynamics (CFD) based unsteady RANS model which enables the prediction of the effect of marine coatings and biofouling on Ship Resistance and presents CFD simulations of the roughness effects on the Resistance and effective power of the full-scale 3D KRISO Container Ship (KCS) hull. Initially, a roughness function model representing a typical coating and different fouling conditions was developed by using the roughness functions given in the literature. This model then was employed in the wall-function of the CFD software and the effects of a typical as applied coating and different fouling conditions on the frictional Resistance of flat plates representing the KCS were predicted for a design speed of 24 knots and a slow steaming speed of 19 knots using the proposed CFD model. The roughness effects of such conditions on the Resistance components and effective power of the full-scale 3D KCS model were then predicted at the same speeds. The resulting frictional Resistance values of the present study were then compared with each other and with results obtained using the similarity law analysis. The increase in the effective power of the full-scale KCS hull was predicted to be 18.1% for a deteriorated coating or light slime whereas that due to heavy slime was predicted to be 38% at a Ship speed of 24 knots. In addition, it was observed that the wave Resistance and wave systems are significantly affected by the hull roughness and hence viscosity.

  • Prediction of the effect of hull fouling on Ship Resistance using CFD
    2014
    Co-Authors: Yigit Kemal Demirel, Khorasanchi, Osman Turan, Atilla Incecik
    Abstract:

    This paper discussed the prediction of the effect of hull fouling on Ship Resistance using CFD.

  • on the importance of antifouling coatings regarding Ship Resistance and powering
    3rd International Conference on Technologies Operations Logistics and Modelling for Low Carbon Shipping, 2013
    Co-Authors: Yigit Kemal Demirel, Osman Turan, Mahdi Khorasanchi, Atilla Incecik
    Abstract:

    This paper aims to introduce one of the latest investigations on development of marine antifouling coatings and also to demonstrate the importance of the type of antifouling coatings on fouling accumulation and Ship Resistance/powering. First, marine biofouling and fouling prevention methods are reviewed. A recent research study (EU FP7 FOUL-X-SPEL Project) concerning a novel and environmentally friendly antifouling coating is presented and discussed. Next, a case study is carried out to assess the effect of fouling on Ship Resistance and powering. A vessel is selected and the roughness on the hull surface induced by different level of fouling is considered. The increase in frictional Resistance and effective power is evaluated for each particular case by using boundary layer similarity law analysis and experimental data. The results emphasise that the type of antifouling coatings has a great importance on the amount of fouling accumulation, hence on Ship performance especially in low speeds

Michael P Schultz - One of the best experts on this subject based on the ideXlab platform.

  • Effects of coating roughness and biofouling on Ship Resistance and powering.
    Biofouling, 2007
    Co-Authors: Michael P Schultz
    Abstract:

    Predictions of full-scale Ship Resistance and powering are made for antifouling coating systems with a range of roughness and fouling conditions. The estimates are based on results from laboratory-scale drag measurements and boundary layer similarity law analysis. In the present work, predictions are made for a mid-sized naval surface combatant at cruising speed and near maximum speed. The results indicate that slime films can lead to significant increases in Resistance and powering, and heavy calcareous fouling results in powering penalties up to 86% at cruising speed. The present estimates show good agreement with results from full-scale Ship power trials.

Soonseok Song - One of the best experts on this subject based on the ideXlab platform.

  • Scale effect on Ship Resistance components and form factor
    Ocean Engineering, 2020
    Co-Authors: Ali Dogrul, Soonseok Song, Yigit Kemal Demirel
    Abstract:

    Abstract To design eco-friendly Ships, the hydrodynamic behaviour of the hull has to be estimated precisely. The first and foremost one is the Ship Resistance, which is closely related to the energy efficiency of the Ship. Different extrapolation methods, based on different assumptions, have been used to predict the full-scale Ship Resistance from model-scale experiments. In this manner, it is important to understand the scale effect on the individual Ship Resistance components. In this study, URANS CFD simulations of KCS and KVLCC2 were conducted at different scales. The total Resistance components were decomposed into the individual Resistance components to investigate the scale effects. The simulation results were compared with full-scale Resistance predictions using different extrapolation methods and the rationale of the different compliances between them was investigated. Finally, the hydrodynamic characteristics in different scales were examined.

  • validation of the cfd approach for modelling roughness effect on Ship Resistance
    Ocean Engineering, 2020
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Abstract Recently, there have been active efforts to investigate the effect of hull roughness on Ship Resistance using Computational Fluid Dynamics (CFD). Although, several studies demonstrated that the roughness modelling in the CFD simulations can precisely predict the increase in frictional Resistance due to the surface roughness, the experimental validations have been made only for flat plates which have zero pressure gradient. This means that the validations cannot necessarily guarantee the validity of this method for other Ship Resistance components besides the frictional Resistance. Therefore, it is worth demonstrating the validity of the roughness modelling in CFD on the total Resistance of a 3D hull. In this study, CFD models of a towed flat plate and a KRISO Container Ship (KCS) model were developed. In order to simulate the roughness effect in the turbulent boundary layer, a previously determined roughness function of a sand-grain surface was employed in the wall-function of the CFD model. Then the result of the CFD simulations was compared with the experimental data. The result showed a good agreement suggesting that the CFD approach can precisely predict the roughness effect on the total Resistance of the 3D hull. Finally, the roughness effects on the individual Ship Resistance components were investigated.

  • Experimental and theoretical study of the effect of hull roughness on Ship Resistance
    Journal of Ship Research, 2020
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Hull roughness increases Ship frictional Resistance and thus results in economic and environmental penalties. Its effect has been prevalently predicted using the similarity law scaling procedure, presented by Granville (1958; 1978). However, this method has not yet been validated with experimental data using a model Ship. This paper presents an experimental investigation into the effect of roughness on Ship Resistance and provides a validation of the similarity law scaling, by using tank testing of a flat plate and a model Ship. Both the plate and the Ship were tested in smooth and rough surface conditions, respectively. For the rough surface conditions, sand grit (aluminium oxide abrasive powder) was applied on the surfaces of the flat plate and the Ship model. The roughness functions of the rough surface were derived by using the results obtained from the flat plate tests. Using the roughness function and the flat plate towing test, the frictional Resistance was extrapolated to the length of the model Ship following the similarity law scaling procedure. The total Resistance of the rough Ship model was first predicted using the extrapolated frictional Resistance and the result of the smooth Ship model, and then compared with the results from the rough Ship model. The predicted total Resistance coefficients for the rough Ship model showed good agreement with the measured total Resistance coefficient of the rough Ship model; thus proving the validity of using Granville’s similarity law scaling to extrapolate the roughness effect on Ship Resistance.

  • Validation of the CFD approach for modelling roughness effect on Ship Resistance
    2019
    Co-Authors: Soonseok Song, Yigit Kemal Demirel, Mehmet Atlar, Osman Turan
    Abstract:

    Recently, there have been active efforts to investigate the effect of hull roughness on Ship Resistance using Computational Fluid Dynamics (CFD). Although, several studies demonstrated that the roughness modelling in the CFD simulations can precisely predict the increase in frictional Resistance due to the surface roughness, the experimental validations have been made only for flat plates which have zero pressure gradient. This means that the validations cannot necessarily guarantee the validity of this method for other Ship Resistance components besides the frictional Resistance. Therefore, it is worth to demonstrate the validity of the roughness modelling in CFD on the total Resistance of a 3D hull. In this study, CFD models of a towed flat plate and a KRISO Container Ship (KCS) model were developed. In order to simulate the roughness effect in the turbulent boundary layer, a previously determined roughness function of a sand-grain surface was employed in the wall-function of the CFD model. Then the result of the CFD simulations was compared with the experimental data. The result showed a good agreement suggesting that the CFD approach can precisely predict the roughness effect on the total Resistance of the 3D hull. Finally, the roughness effects on the individual Ship Resistance components were investigated.