The Experts below are selected from a list of 483 Experts worldwide ranked by ideXlab platform

Mehmet Atlar - One of the best experts on this subject based on the ideXlab platform.

  • effects of in service conditions mimicked Hull Roughness ranges and biofilms on the surface and the hydrodynamic characteristics of foul release type coatings
    Biofouling, 2020
    Co-Authors: Irma Yeginbayeva, Mehmet Atlar, Serkan Turkmen, H Chen
    Abstract:

    To develop a better understanding of ‘in-service’ performance of modern marine coatings, this study explored the combined effects of different Roughness ranges of foul-release coating (FRC) and lig...

  • validation of the cfd approach for modelling Roughness effect on ship resistance
    Ocean Engineering, 2020
    Co-Authors: Soonseok Song, Mehmet Atlar, Yigit Kemal Demirel, 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.

  • Validation of the CFD approach for modelling Roughness effect on ship resistance
    2019
    Co-Authors: Soonseok Song, Mehmet Atlar, Yigit Kemal Demirel, Saishuai Dai, Sandy Day, 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.

  • an experimental investigation into the surface and hydrodynamic characteristics of marine coatings with mimicked Hull Roughness ranges
    Biofouling, 2018
    Co-Authors: Irma Yeginbayeva, Mehmet Atlar
    Abstract:

    There are limited scientific data on contributors to the added drag of in-service ships, represented by modern-day coating Roughness and biofouling, either separately or combined. This study aimed to gain an insight into Roughness and hydrodynamic performance of typical coatings under in-service conditions of roughened ships’ Hull surfaces. Comprehensive and systematic experimental data on the boundary layer and drag characteristics of antifouling coating systems with different finishes are presented. The coating types investigated were linear-polishing polymers, foul-release and controlled-depletion polymers. The data were collected through state-of the-art equipment, including a 2-D laser Doppler velocimetry (LDV) system for hydrodynamic data in a large circulating water tunnel. Three coating systems were first applied on flat test panels with ‘normal’ finishes in the first test campaign to represent coating applications under idealised laboratory conditions. In order to address more realistic Roughness conditions, as typically observed on ships’ Hulls, ‘low’ and ‘high’ Roughness densities were introduced into the same types of coating, in the second test campaign. The data collected from the first test campaign served as the baseline to demonstrate the effect on the surface Roughness and hydrodynamic drag characteristics of these coating types as a result of ‘in-service’ or ‘severely flawed’ coating application scenarios. Data collected on coatings with a range of in-service surface conditions provided a basis to establish correlation between the surface Roughness characteristics and hydrodynamic performance (Roughness function). The findings of the study indicate that the estimations of drag penalties based on well-applied, relatively smooth coating conditions underestimate the importance of Hull Roughness, which although undesirable, is commonplace in the world’s commercial fleet.

Irma Yeginbayeva - One of the best experts on this subject based on the ideXlab platform.

  • effects of in service conditions mimicked Hull Roughness ranges and biofilms on the surface and the hydrodynamic characteristics of foul release type coatings
    Biofouling, 2020
    Co-Authors: Irma Yeginbayeva, Mehmet Atlar, Serkan Turkmen, H Chen
    Abstract:

    To develop a better understanding of ‘in-service’ performance of modern marine coatings, this study explored the combined effects of different Roughness ranges of foul-release coating (FRC) and lig...

  • an experimental investigation into the surface and hydrodynamic characteristics of marine coatings with mimicked Hull Roughness ranges
    Biofouling, 2018
    Co-Authors: Irma Yeginbayeva, Mehmet Atlar
    Abstract:

    There are limited scientific data on contributors to the added drag of in-service ships, represented by modern-day coating Roughness and biofouling, either separately or combined. This study aimed to gain an insight into Roughness and hydrodynamic performance of typical coatings under in-service conditions of roughened ships’ Hull surfaces. Comprehensive and systematic experimental data on the boundary layer and drag characteristics of antifouling coating systems with different finishes are presented. The coating types investigated were linear-polishing polymers, foul-release and controlled-depletion polymers. The data were collected through state-of the-art equipment, including a 2-D laser Doppler velocimetry (LDV) system for hydrodynamic data in a large circulating water tunnel. Three coating systems were first applied on flat test panels with ‘normal’ finishes in the first test campaign to represent coating applications under idealised laboratory conditions. In order to address more realistic Roughness conditions, as typically observed on ships’ Hulls, ‘low’ and ‘high’ Roughness densities were introduced into the same types of coating, in the second test campaign. The data collected from the first test campaign served as the baseline to demonstrate the effect on the surface Roughness and hydrodynamic drag characteristics of these coating types as a result of ‘in-service’ or ‘severely flawed’ coating application scenarios. Data collected on coatings with a range of in-service surface conditions provided a basis to establish correlation between the surface Roughness characteristics and hydrodynamic performance (Roughness function). The findings of the study indicate that the estimations of drag penalties based on well-applied, relatively smooth coating conditions underestimate the importance of Hull Roughness, which although undesirable, is commonplace in the world’s commercial fleet.

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, Mehmet Atlar, Yigit Kemal Demirel, 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.

  • Validation of the CFD approach for modelling Roughness effect on ship resistance
    2019
    Co-Authors: Soonseok Song, Mehmet Atlar, Yigit Kemal Demirel, Saishuai Dai, Sandy Day, 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.

  • 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.

  • a cfd model for the frictional resistance prediction of antifouling coatings
    Ocean Engineering, 2014
    Co-Authors: Yigit Kemal Demirel, Mahdi Khorasanchi, Osman Turan, Atilla Incecik, Michael P. Schultz
    Abstract:

    The fuel consumption of a ship is strongly influenced by her frictional resistance, which is directly affected by the Roughness of the Hull׳s surface. Increased Hull Roughness leads to increased frictional resistance, causing higher fuel consumption and CO2 emissions. It would therefore be very beneficial to be able to accurately predict the effects of Roughness on resistance. This paper proposes a Computational Fluid Dynamics (CFD) model which enables the prediction of the effect of antifouling coatings on frictional resistance. It also outlines details of CFD simulations of resistance tests on coated plates in a towing tank. Initially, Roughness functions and Roughness Reynolds numbers for several antifouling coatings were evaluated using an indirect method. Following this, the most suitable Roughness function model for the coatings was employed in the wall-function of the CFD software. CFD simulations of towing tests were then performed and the results were validated against the experimental data given in the literature. Finally, the effects of antifouling coatings on the frictional resistance of a tanker were predicted using the validated CFD model.

  • A parametric study: Hull Roughness effect on ship frictional resistance
    2013
    Co-Authors: Yigit Kemal Demirel, Osman Turan, Atilla Incecik, Khorasanchi
    Abstract:

    Ship resistance is very important in terms of ship performance and fuel consumption. The more resistance a ship has, the more fuel it consumes for the same range. Ship resistance can be broken into two parts; frictional resistance and residuary resistance. Especially for merchant ships which sail with normal or low velocity, frictional resistance may be 60-90% of the total resistance and it is directly affected by surface Roughness; namely physical and biological Roughness. Hull Roughness leads to frictional resistance increase which means fuel penalty. Marine coatings are widely used in order to avoid or minimise fouling and Hull Roughness, hence increase in frictional resistance. This paper outlines details of a parametric numerical study which was carried out to monitor the effect of changing surface Roughness of marine coatings on ship frictional resistance. This investigation was made by means of a computational fluid dynamics (CFD) based software (STAR-CCM+). Firstly, towing test simulations of a flat plate were conducted and the results were compared with the experimental results given in literature to validate the model. After the validation procedure, a parametric study was carried out to obtain frictional resistance and frictional drag coefficient variations depending on various Hull Roughness conditions. Moreover, a simple formulation which correlates the Roughness height and frictional drag coefficient was obtained within the validated Roughness height range and speed. Finally, the results were presented in both graphical and tabular forms and discussed in details.

Yigit Kemal Demirel - 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, Mehmet Atlar, Yigit Kemal Demirel, 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.

  • Validation of the CFD approach for modelling Roughness effect on ship resistance
    2019
    Co-Authors: Soonseok Song, Mehmet Atlar, Yigit Kemal Demirel, Saishuai Dai, Sandy Day, 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.

  • 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.

  • a cfd model for the frictional resistance prediction of antifouling coatings
    Ocean Engineering, 2014
    Co-Authors: Yigit Kemal Demirel, Mahdi Khorasanchi, Osman Turan, Atilla Incecik, Michael P. Schultz
    Abstract:

    The fuel consumption of a ship is strongly influenced by her frictional resistance, which is directly affected by the Roughness of the Hull׳s surface. Increased Hull Roughness leads to increased frictional resistance, causing higher fuel consumption and CO2 emissions. It would therefore be very beneficial to be able to accurately predict the effects of Roughness on resistance. This paper proposes a Computational Fluid Dynamics (CFD) model which enables the prediction of the effect of antifouling coatings on frictional resistance. It also outlines details of CFD simulations of resistance tests on coated plates in a towing tank. Initially, Roughness functions and Roughness Reynolds numbers for several antifouling coatings were evaluated using an indirect method. Following this, the most suitable Roughness function model for the coatings was employed in the wall-function of the CFD software. CFD simulations of towing tests were then performed and the results were validated against the experimental data given in the literature. Finally, the effects of antifouling coatings on the frictional resistance of a tanker were predicted using the validated CFD model.

  • A parametric study: Hull Roughness effect on ship frictional resistance
    2013
    Co-Authors: Yigit Kemal Demirel, Osman Turan, Atilla Incecik, Khorasanchi
    Abstract:

    Ship resistance is very important in terms of ship performance and fuel consumption. The more resistance a ship has, the more fuel it consumes for the same range. Ship resistance can be broken into two parts; frictional resistance and residuary resistance. Especially for merchant ships which sail with normal or low velocity, frictional resistance may be 60-90% of the total resistance and it is directly affected by surface Roughness; namely physical and biological Roughness. Hull Roughness leads to frictional resistance increase which means fuel penalty. Marine coatings are widely used in order to avoid or minimise fouling and Hull Roughness, hence increase in frictional resistance. This paper outlines details of a parametric numerical study which was carried out to monitor the effect of changing surface Roughness of marine coatings on ship frictional resistance. This investigation was made by means of a computational fluid dynamics (CFD) based software (STAR-CCM+). Firstly, towing test simulations of a flat plate were conducted and the results were compared with the experimental results given in literature to validate the model. After the validation procedure, a parametric study was carried out to obtain frictional resistance and frictional drag coefficient variations depending on various Hull Roughness conditions. Moreover, a simple formulation which correlates the Roughness height and frictional drag coefficient was obtained within the validated Roughness height range and speed. Finally, the results were presented in both graphical and tabular forms and discussed in details.

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

  • Experimental investigation of the effect of heterogeneous Hull Roughness on ship resistance
    2021
    Co-Authors: Song Soonseok, Demirel, Yigit Kemal, Atlar Mehmet, Ravenna Roberto, Dai Saishuai, Demarco Muscat-fenech Claire, Tani Giorgio, Day Sandy, Incecik Atilla
    Abstract:

    There has been an increasing attention to the effect of Hull Roughness on ship resistance and powering. In conventional studies, the Hull surfaces have been treated as uniform rough surfaces while the real ships' Hulls are exposed heterogeneous fouling accumulation. The work described here presents an experimental investigation into the effect of heterogeneous Hull Roughness on ship resistance. A series of towing tests were conducted using a ship model of the Wigley Hull with various Hull Roughness conditions, including homogeneous conditions (i.e. smooth and full-rough conditions) and heterogeneous conditions (i.e. ¼-bow-rough, ¼-aft-rough, ½-bow-rough and ½-aft-rough conditions). The bow-rough conditions (e.g. ¼-bow-rough and ½-bow-rough) showed larger added resistance than aft-rough conditions (e.g. ¼-aft-rough and ½-aft-rough) with the same wetted surface area of the rough region. This finding suggests that the Hull Roughness of the forward part of the Hull is more significant than the others in terms of the added resistance. Finally, a new method was proposed to predict the added resistance due to the heterogeneous Hull Roughness based on Granville's similarity law scaling and the predictions were compared with the experimental result

  • Investigating the effect of heterogeneous Hull Roughness on ship resistance using CFD
    'MDPI AG', 2021
    Co-Authors: Song Soonseok, Demirel, Yigit Kemal, Demarco Muscat-fenech Claire, Sant Tonio, Villa Diego, Tezdogan Tahsin, Incecik Atilla
    Abstract:

    Research into the effects of Hull Roughness on ship resistance and propulsion is well established, however, the effect of heterogeneous Hull Roughness is not yet fully understood. In this study, Computational Fluid Dynamics (CFD) simulations were conducted to investigate the effect of heterogeneous Hull Roughness on ship resistance. The Wigley Hull was modelled with various Hull conditions, including homogeneous and heterogeneous Hull conditions. The results were compared against existing experimental data and showed a good agreement, suggesting that the CFD approach is valid for predicting the effect of heterogeneous Hull Roughness on ship resistance. Furthermore, the local distributions of the wall shear stress and Roughness Reynolds number on the Hull surface were examined to assess the flow characteristics over the heterogeneous Hull Roughness