Journal of Ship Research最新文献

{"title":"Experimental and Numerical Investigation of Green Water Occurrence for KRISO Container Ship","authors":"K. R. Babu, Sri Vinay Krishna Rayudu Nelli, A. Bhattacharyya, R. Datta","doi":"10.5957/JOSR.08200049","DOIUrl":"https://doi.org/10.5957/JOSR.08200049","url":null,"abstract":"The occurrence of green water on the deck of Korea Research Institute of Ships & Ocean Engineering (KRISO) container ship is investigated using model test experiments and a fully coupled impulse response function (IRF)-computational fluid dynamics (CFD)-based numerical approach. In the experimental study, green water pressure over the deck and superstructure is investigated for different regular head wave conditions (wavelength/ship length ratio: .8-1.5) and vessel speeds (Froude number: .055-.166). The impact pressure on the deck is found to be highest at a wavelength/ship length ratio of 1.2 and increases drastically with the increase in Froude number. The variation of green water pressure with wave steepness is linear for points on the forward deck and quadratic for the superstructure. In the second part, a coupled IRF-CFD-based numerical method is developed in which the global hydrodynamic forces such as radiation-diffraction and Froude-Krylov force are computed using a potential flow solver, whereas the local pressure due to the shipping water impact is computed using CFD and added as an external force. Comparisons of vessel motions and green water pressures with experiments indicate that the coupled IRF-CFD method can be a robust and efficient tool to predict shipping water loads on ships.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45483725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the Interplay of Shape and Physical Parameters by Unsupervised Nonlinear Dimensionality Reduction Methods","authors":"A. Serani, D. D’Agostino, E. Campana, M. Diez","doi":"10.5957/josr.09180056","DOIUrl":"https://doi.org/10.5957/josr.09180056","url":null,"abstract":"The article presents an exploratory study on the application to ship hydrodynamics of unsupervised nonlinear design-space dimensionality reduction methods, assessing the interaction of shape and physical parameters. Nonlinear extensions of the principal component analysis (PCA) are applied, namely local PCA (LPCA) and kernel PCA (KPCA). An artificial neural network approach, specifically a deep autoencoder (DAE) method, is also applied and compared with PCA-based approaches. The data set under investigation is formed by the results of 9000 potential flow simulations coming from an extensive exploration of a 27-dimensional design space, associated with a shape optimization problem of the DTMB 5415 model in calm water at 18 kn (Froude number, Fr = 25). Data include three heterogeneous distributed and suitably discretized parameters (shape modification vector, pressure distribution on the hull, and wave elevation pattern) and one lumped parameter (wave resistance coefficient), for a total of 9000 x 5101 elements. The reduced-dimensionality representation of shape and physical parameters is set to provide a normalized mean squared error smaller than 5%. The standard PCA meets the requirement using 19 principal components/parameters. LPCA and KPCA provide the most promising compression capability with 14 parameters required by the reduced-dimensionality parametrizations, indicating significant nonlinear interactions in the data structure of shape and physical parameters. The DAE achieves the same error with 17 components. Although the focus of the current work is on design-space dimensionality reduction, the formulation goes beyond shape optimization and can be applied to large sets of heterogeneous physical data from simulations, experiments, and real operation measurements.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48900773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Ship-Induced Langmuir-Type Circulations on Distribution of Surface-Active Substances and Damping of Short Wind Waves","authors":"Ryan Somero, A. Basovich, E. Paterson","doi":"10.5957/josr.10180090","DOIUrl":"https://doi.org/10.5957/josr.10180090","url":null,"abstract":"It has recently been shown that the interaction of ship-generated nonuniform currents with ambient surface waves can lead to the generation of Langmuir-type circulations (LTCs) (Basovich 2011) and a persistent wake (Somero et al. 2018). Based on this work, it is shown here that the LTC and surface currents of the persistent wake are responsible for the redistribution of surface-active substances (SAS) and a corresponding change in the damping of short surface waves. The persistent wake is a region of the ship wake, where initial ship-generated perturbations have mostly decayed. The LTCs are similar in nature to Langmuir circulations which arise as a result of instability of wind-driven current. LTCs produce a secondary flow with velocity transverse to the direction of the ship, and width significantly larger than the ship beam. Because LTCs are generated in large scale, they persist for a long time after the passage of the ship. Transverse surface currents produced by LTCs in the ship wake redistribute the SAS films at the sea surface. These currents create strong convergence and divergence zones which in turn produce streaks with different concentrations of SAS. The change in concentration of SAS affects the film pressure and the damping effect of SAS on the short surface waves. This effect is represented by a damping factor and is a crucial parameter in determination of the spectral density of short wind waves. Therefore, the damping effect of the film, as represented by the damping factor, is responsible for sea surface roughness modification and is important for prediction of synthetic-aperture RADAR (SAR) imagery of ship wakes on the ocean surface. In this article, we present the mathematical and computational methods, along with simulation results for a naval surface combatant operating in calm, head, and following seas. The simulation results clearly show that the convergence and divergence zones strongly influence the relative SAS concentration and the spatial distribution of the damping factor, the latter of which defines the structure of SAR images of the persistent wake. Comparisons of the magnitude of the damping factor with available SAR data are shown to be in good agreement.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48919745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Analysis of Repair Welding Alternatives for Shipbuilding DH36 Plates","authors":"T. Gurova, S. Estefen, A. Leontiev, Plínio T. Barbosa, V. Zhukov, Vasilii Nikulin","doi":"10.5957/JOSR.07180035","DOIUrl":"https://doi.org/10.5957/JOSR.07180035","url":null,"abstract":"Repair by welding is widely used in the shipbuilding industry during ship construction. The effect of the residual stress distribution induced by the welding process on the ship structure is important for the repair effectiveness. This article presents an experimental study of the residual stress distribution induced by repair welding in the plates that are typically used in ships and offshore structures. Different repair techniques are evaluated to identify the best practice associated with residual stress values. Recommendations for repair welding are discussed, and modifications to the present practice are proposed.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":"64 1","pages":"384-391"},"PeriodicalIF":1.4,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43836919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Captive Model Tests for Assessing Maneuverability of a Damaged Surface Combatant with Initial Heel Angle","authors":"Jeonghwa Seo, D. Kim, J. Ha, S. Rhee, H. Yoon, Jongyeol Park, W. Seok, K. Rhee","doi":"10.5957/JOSR.09180075","DOIUrl":"https://doi.org/10.5957/JOSR.09180075","url":null,"abstract":"The present study is about the application of a four-degree-of-freedom (4DOF) maneuvering mathematical model based on Abkowitz’s model for assessing damaged ship maneuverability with initial asymmetry. A scaled model of the Office of Naval Research Tumblehome hull with a damaged compartment was used as the test model. Based on the survivability regulations for naval vessels, the damaged compartment was designed and located near the bow, such that it had an initial heel and trim. Static and dynamic captive model tests were performed on the damaged ship model to determine the maneuvering coefficients for the maneuvering mathematical model. Maneuvering simulations were carried out with the captive model test data and 4DOF maneuvering mathematical model. The advance speed in the maneuver reduced more in the damaged condition than in the intact condition, and maneuverability was severely degraded during starboard turning.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46794780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of a Container Ship with Breaking Waves at High Froude Number Using URANS and DDES Methods","authors":"Jianhua Wang, Z. Ren, D. Wan","doi":"10.5957/josr.09180081","DOIUrl":"https://doi.org/10.5957/josr.09180081","url":null,"abstract":"The KRISO container ship model is used for numerical simulations to investigate hydrodynamic performance under high speeds. Unsteady Reynolds-Averaged Navier-Stokes (URANS) and delayed detached eddy simulation (DDES) approaches are used to resolve the flow field around the ship model. High-resolution Volume of Fluid (VOF) technique in OpenFOAM is used to capture the free surface. The present work focuses on the wave-breaking phenomena of high-speed ships. To study the speed effects on the phenomenon of ship bow wave breaking, three different speeds, i.e., Fn = .26, .35, and .40, are investigated for a fixed ship model in calm water. Predicted resistance and wave patterns under Fn = .26 are validated with available experimental data, and a good agreement is achieved. The breaking wave phenomena can be observed from both URANS and DDES results for Froude numbers greater than .35. And the Fn = .40 case shows more violent breaking bow waves. The process of overturning and breaking of bow wave is more complex in the DDES results, and some small-scale free surface features are also captured. The predicted bow wave is compared with the experiment conducted at the China Ship Scientific Research Center. It shows that the DDES results are more accurate. Wave profiles and vorticity field at several cross sections are presented to illustrate the relationship between bow waves and vortices. It is found that the free surface vorticity dissipates quickly in the URANS simulation, which leads to the difference compared with the DDES results.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46644888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling Bubble Entrainment and Transport for Ship Wakes: Progress Using Hybrid RANS/LES Methods","authors":"Jiajia Li, Ben Yuan, P. Carrica","doi":"10.5957/josr.09180071","DOIUrl":"https://doi.org/10.5957/josr.09180071","url":null,"abstract":"This article presents progress on modeling bubble entrainment and transport around ships using hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/ LES) methods. Previous results using a Boltzmann-based polydisperse bubbly flow model show that LES perform better than RANS in predicting transport of bubbles to depth, a very important process to predict bubbly wakes. However, standard DES-type models fail to predict proper turbulent kinetic energy (TKE) and dissipation, needed by bubble entrainment, breakup, and coalescence models. We propose different approaches to obtain TKE and dissipation in LES regions and evaluate them for cases of increasing complexity, including decay of isotropic turbulence, a flat plate boundary layer, and the flow in the wake of the research vessel Athena. An exponential weighted average is used to estimate statistics and obtain the averaged quantities in regions with resolved turbulence. The TKE is satisfactorily predicted in the cases tested. A modified ω equation in the SST model is proposed to implicitly compute the dissipation, showing superior results than the standard DES models, although further improvements are necessary. A hybrid RANS/LES approach is proposed, which focused at conserving total TKE as the flow crosses RANS/LES interfaces, as previously performed for zonal approaches but attempting a DES-like detection of regions suitable for LES, critical for large-scale computations of bubbly flows involving complex geometries. A general form of a dynamic forcing term is derived to transfer the modeled TKE to resolved TKE with a controller to guarantee proper conservation of the energy transferred. It was verified that the model is not sensitive to grid size or time step. Improvements to DDES and the proposed TKE-conserving hybrid RANS/ LES method show encouraging results, although remaining challenges are discussed.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48887380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultimate Strength of Hull Structural Stiffened Plate with Grooving Corrosion Damage under Uniaxial Compression","authors":"Yufan Zhu, Yan Zhang, F. Du","doi":"10.5957/JOSR.03200014","DOIUrl":"https://doi.org/10.5957/JOSR.03200014","url":null,"abstract":"Grooving corrosion results in a decrease in the ability of the structure to resist external loads. In the present study, a new assessment method was developed to investigate the ultimate loading capacity of stiffened plates with grooving corrosion damage. First, the basic parameters of stiffened plates (including model range, boundary condition, welding residual stress, initial geometric imperfection, and size of finite element) were assumed. Second, the influences of corrosion parameters and geometrical parameters of stiffened plates (such as finite element type, groove width, groove depth, groove depth-to-width ratio, plate flexibility, stiffener flexibility, and number of stiffeners) were analyzed. Third, based on the data analysis from a large number of nonlinear finite element analyses, the ultimate strength reduction formula of stiffened plates was derived. Last, the correctness of the formula was verified by ultimate strength experiment.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":"1-11"},"PeriodicalIF":1.4,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45550192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced Unified Theory with Forward-Speed Effect Taken into Account in the Inner Free-Surface Condition","authors":"M. Kashiwagi","doi":"10.5957/JOSR.04200028","DOIUrl":"https://doi.org/10.5957/JOSR.04200028","url":null,"abstract":"The enhanced unified theory (EUT) has been used as a core theory in the integrated system developed at the Research Initiative on Oceangoing Ships (RIOS) of Osaka University for predicting the propulsion and seakeeping performance of a ship in actual seas. In this study, the EUT is modified by adopting partially the solution method in the rational strip theory of Ogilvie and Tuck as a particular solution in the inner problem, thereby a forward-speed effect in the convection term of the free-surface condition is incorporated in the inner solution. This forward-speed effect is analytically shown to contribute only to the cross-coupling radiation forces. Some other forward-speed and 3D effects important in a low-frequency range are also included in the homogeneous component of the inner solution through matching with the outer solution in a similar manner to the unified theory of Newman. Numerical computations are implemented for a slender modified Wigley model and the RIOS bulk carrier model. Good agreement is confirmed in a comparison with experimental data for the cross-coupling added mass and damping coefficients between heave and pitch and also for the resulting ship motions, particularly in heave near the resonant frequency. The added resistance around the motion-resonant wavelength is found to be improved but sensitive to a slight change in heave and pitch motions. Thus, it is stressed that accurate prediction of the ship motions and resultant Kochin function is critical for more accurate prediction of the added resistance in waves.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":"1-14"},"PeriodicalIF":1.4,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49513992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Turbulent Skin Friction Reduction through the Application of Superhydrophobic Coatings to a Towed Submerged SUBOFF Body","authors":"J. Gose, Kevin Golovin, Mathew Boban, Brian Tobelmann, E. Callison, J. Barros, M. Schultz, A. Tuteja, M. Perlin, S. Ceccio","doi":"10.5957/JOSR.10190060","DOIUrl":"https://doi.org/10.5957/JOSR.10190060","url":null,"abstract":"In the present study, the drag-reducing effect of sprayed superhydrophobic surfaces (SHSs) is determined for two external turbulent boundary layer (TBL) flows. We infer the modification of skin friction created beneath TBLs using near-wall laser Doppler velocity measurements for a series of tailored SHSs. Measurements of the near-wall Reynolds stresses were used to infer reduction in skin friction between 8% and 36% in the channel flow. The best candidate SHS was then selected for application on a towed submersible body with a SUBOFF profile. The SHS was applied to roughly 60% of the model surface over the parallel midbody of the model. The measurements of the towed resistance showed an average decrease in the overall resistance from 2% to 12% depending on the speed and depth of the towed model, which suggests a SHS friction drag reduction of 4-24% with the application of the SHS on the model. The towed model results are consistent with the expected drag reduction inferred from the measurements of a near-zero pressure gradient TBL channel flow.","PeriodicalId":50052,"journal":{"name":"Journal of Ship Research","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43906463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}