Viscous Models Comparison in Water Impact of Twin 2D Falling Wedges Simulation by Different Numerical Solvers 2 2 In this paper, symmetric water entry of twin wedges is investigated for deadrise angle of 30 degree. Three numerical simulation of a symmetric impact, considering rigid body dynamic equations of motion in two-phase flow is presented. The two-phase flow around the wedges is solved by Finite Element based on Finite Volume method (FEM-FVM) which is used in conjunction with Volume of Fluid (VOF) scheme in ANSYS Fluent and ANSYS CFX and Phase Field scheme in COMSOL Multiphysics. The method and scheme of simulation are validated by experimental data for geometry with one wedge. The dynamic mesh, mesh motion and moving mesh models are used to simulate dynamic motion of the wedges in ANSYS Fluent, ANSYS CFX and COMSOL Multiphysics, respectively. The vertical velocity and pressure coefficient versus time are determined and comparisons of the computed mentioned parameters against experimental data are performed. The eight characteristics effects of fluid flow are investigated till 0.25 second after wedges falling including impact event. It is demonstrated that the ANSYS Fluent and k-ε were the best software and viscous model, respectively. 1 13 2017/03/17 1395/12/27 2017/11/9 1396/8/18 Mehdi Mahmoodi Mehdi Mahmoodi Babol Noshirvani University of Technology iran mehdymahmoody@gmail.com Roya Shademani Roya Shademani Amirkabir University of Technology iran shdmn@aut.ac.ir Mofid Gorji Bandpy Mofid Gorji Bandpy Babol Noshirvani University of Technology iran gorji@nit.ac.ir Falling Wedges Two Phases Phase Field Volume of Fluid Dynamic Mesh 1- Xu, G.D., Duan, W.Y., and Wu, G.X., (2008), Numerical simulation of oblique water entry of an asymmetrical wedge, J. Ocean Engineering, Vol.35, p.1597-1603.##2- Von Karman, T., (1929), The impact of seaplane floats during landing, NACA TN 321, Washington, DC.##3- Wagner, H., (1932), The phenomena of impact and planing on water. National Advisory Committee for Aeronautics, Translation, 1366, Washington, DC ZAMM. J. App. Math. Mech. Vol.12(4), p.193–215.##4- Shademani R. and Ghadimi, P., (2017), Asymmetric water entry of twin wedges with different deadrises, heel angles, and wedge separations using finite element based finite volume method and VOF, Journal of Applied Fluid Mechanics, Vol.10(1), p.353-368.##5- Ghazizade-Ahsaee, H. and Nikseresht, A.H., (2013), Numerical Simulation of Two Dimensional Dynamic Motion of the Symmetric Water Impact of a Wedge, International journal of maritime technology, Vol.1(1), p.11-22.##6- Armand, J.L. and Cointe, R., (1987), Hydrodynamic impact analysis of a circular cylinder, 5th International Offshore Mechanics and Arctic Engineering. Tokyo, p.609-634.##7- Greenhow, M. (1987), Wedge entry into initially calm water, J. Applied Ocean Research. Vol.9, p.214-233.##8- Farsi, M. and Ghadimi, P., (2015), Simulation of 2D symmetry and asymmetry wedge water entry by smoothed particle hydrodynamics method, J Braz. Soc. Mech. Sci. Eng. Vol.37(3), p.821-835.##9- Farsi, M. and Ghadimi, P., (2016), Effect of flat deck on catamaran water entry through smoothed particle hydrodynamics, In Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, Vol.230(2), p.267-280.##10- Yamada, Y., Takami, T. and Oka, M., (2012), Numerical study on the slamming impact of wedge shaped obstacles considering fluidstructure interaction (FSI), In Proceedings of the International Offshore and Polar Engineering Conference.##11- Luo, H., Wang, H. and Soares, C.G., (2012), Numerical and experimental study of hydrodynamic impact and elastic response of one free-drop wedge with stiffened panels, Ocean Eng. Vol.40, p.1-14.##12- Ghadimi, P., Saadatkhah, A. and Dashtimanesh, A. (2011), Analytical solution of wedge water entry by using Schwartz-Christoffel conformal mapping, Int. J. Model. Sim. Sci. Compu. Vol.2(3), p.337-354.##13- Shah, S.A., Orifici, A.C. and Watmuff, J.H., (2015), Water impact of rigid wedges in twodimensional fluid flow, Journal of Applied Fluid Mechanics Vol.8(2), p.329-338.##14- Panahi, R., (2012), Simulation of water-entry and water-exit problems using a moving mesh algorithm, J. of Theoretical and Applied Mechanics, Vol.42, p.79–92.##15- Panciroli, R., (2013), Water entry of flexible wedges: Some issues on the FSI phenomena, App. Ocean Res, Vol.39, p.72-74.##16- Piro, D.J. and Maki K., (2013), Hydroelastic analysis of bodies that enter and exit water, J. Fluids and Structures, Vol.37, p.134-150.##17- Zhao, R. and Faltinsen, O.M., (1993), Water entry of two-dimensional bodies, J. Fluid Mechanics, Vol.246, p.593–612.## ##

Cost-Benefit Investigation of Offshore Wind Power Generation for Soroush Offshore Complex 2 2 Iranian offshore oil and gas platforms are mostly located in the Persian Gulf. Technical and environmental challenges resulted from an off-design running condition of processes on a platform are important issues. The weakness of strategies to stop or decrease the amount of greenhouse gas emission production rate in the Persian Gulf; which is intensively increasing, is another matter of concern. modern methods of energy generation from available renewable potentials near offshore platforms are suggested. Integration of renewable energy converters with offshore oil and gas platforms can solve both problems with machinery and environment to an acceptable extent. In this study, the economics of the Soroush offshore complex is subjected to two scenarios. The first scenario defines the present condition in which the total power demand of the complex is supplied by burning the associated extracted natural gas on board the platform in its thermal power plant and the second scenario considers a wind farm located near Bardekhun in Bushehr province to be connected to the complex power network and shares its renewable source generated power with the platform. The economics of both scenarios are compared in terms of total annual power cost. The second scenario shows more beneficial, although there are some conservative assumptions included due to a shortage of data and limitations. 15 21 2017/03/172017/05/15 1396/2/25 2017/11/92017/09/27 1396/7/5 Shahab Shahriari Shahab Shahriari Petroleum University of Technology iran sh.shahriari@mnc.put.ac.ir Pedram Edalat Pedram Edalat Petroleum University of Technology iran edalat@put.ac.ir Gholamreza Salehi Gholamreza Salehi Petroleum University of Technology iran Gh.salehi@put.ac.ir Soroush oilfield Renewable energy wind power environmental pollution the Persian Gulf Baringbing, J., Kandepu, R., Beyer, H.-G., Randeberg, E. and LundBo, O., (2011), Integration of fuel-based energy with offshore oil and gas installation with wind farms, main grids and other renewable energy systems, M.Sc Thesis, Stavanger.##Mekhiche, M. and Kathleen, A. E., (2014), A renewable energy source for powering offshore oil and gas applications, 19th Offshore Symposium, pp. 1–11.##Tiong, Y. K., Zahari, M. A., Wong, S. F. and Dol, S. S., (2015), The Feasibility of Wind and Solar Energy Application for Oil and Gas Offshore Platform, Material Science Engineering, vol. 78, no. 12042.##Zahari, M. A. and Dol, S. S., (2014), Application of Vortex Induced Vibration Energy Generation Technologies to the Offshore Oil and Gas Platform : The Preliminary Study, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering, vol. 8, no. 7, pp. 1321–1324.##Eriksson, S., Bernhoff, H. and Leijon, M., (2008), Evaluation of different turbine concepts for wind power, Renewable Sustainable Energy Review., vol. 12, no. 5, pp. 1419–1434, 2008.##Vannuci, D., (2011), WP3 technologies State of the Art.##M. M. Aslam Bhutta, N. Hayat, A. U. Farooq, Z. Ali, S. R. Jamil, and Z. Hussain, (2012), Vertical axis wind turbine - A review of various configurations and design techniques, Renewable Sustainable Energy Review, vol. 16, no. 4, pp. 1926–1939.##Hj Mohd Amin, M. F., (2014), Use of Alternative Energies in the Australian Offshore Sector, Australian maritme college.##Shahriari, S., Bagherinia, M. S. and Edalat, P., (2016), A green power supply method for offshore oil and gas platforms in order to reduce associated environmental pollutions in Persian Gulf, 18th Marine Industries Conference.##Barrera Limón, J. A., (2006), Offshore Wind Farms Connection to Grid, Eindhoven University of Technology.##eia, (2017), Natural Gas Intelligence, [Online]. Available: http://www.naturalgasintel.com/.##Reiszadeh, M. and Motahar, M., (2011), The wind energy potential in the coasts of Persian Gulf used in design and analysis of a horizontal axis wind turbine, World Renewable Energy Congress, pp. 4058–4065.##Wind Turbine SWT-3.6-120 Technical specifications, (2016), Siemens AG, Germany.##Multon, B., (2012), Marine Renewable Energy Handbook. London: John Wiley & Sons, Inc.##Public Organizational Announcement of Ministry of Energy, Tehran, 95/14273/30/100.##Mone, C., Stehly, T., Maples, B. and Settle, E., (2015), 2014 Cost of Wind Energy Review, Denver.## ##

Investigation of the Effect of Local Buckling and VIV Fatigue on Failure Probability of Subsea Pipelines in Iranian South Pars Gas Field 2 2 Free-span occurs normally in a pipeline at uneven seabed, dynamic seabed and pipeline crossing. Free spanning in pipeline causes Vortex Induced Vibration (VIV) fatigue, fracture and bursting. In this paper, a pipeline located in South Pars Gas Field is assessed against local buckling and VIV fatigue using probability of failure theory based on the recommended methodology by Det Norske Veritas (DNV) corresponding to different soil classes and different span length to pipeline diameter and also different water depths by applying First-Order Reliability Method (FORM) and Monte-Carlo Sampling (MCS), separately. Furthermore, the simultaneous effect of local buckling and VIV fatigue is assessed in terms of probability of failure. Finally, in order to determine the effect of each parameter on failure probability, sensitivity analysis is carried out using the alpha index. 23 32 2017/03/172017/05/152017/08/5 1396/5/14 2017/11/92017/09/272018/01/8 1396/10/18 Abdolrahim Taheri Abdolrahim Taheri Assisstant prof. in offshore strcutures, petroleum university of technology iran rahim.taheri@put.ac.ir mahdi shabani mahdi shabani MS.C in offshore structures iran m.shabani@mnc.put.ac.ir Mohammad Daghigh Mohammad Daghigh Assisstant Prof. in offshore structures iran daghigh@pogc.ir subsea pipeline probability of failure free span local buckling 1- Bai, Q. and Bai, Y., (2014), “1 - Introduction,” in Subsea Pipeline Design, Analysis, and Installation, Boston: Gulf Professional Publishing, p. 3–21.##2- Mustaffa, Z., (2011), System Reliability Assessment of Offshore Pipelines, PhD Thesis, University of Delft, Netherland.##3- “DNV-OS-F101: Submarine Pipeline Systems (2010).##4- Rezazadeh, K., Zhu, L., Bai, Y., and Zhang, L. , (2010), Fatigue Analysis of Multi-Spanning Subsea Pipeline, In Proceedings of 29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 5, Parts A and B, p. 805–812.##5- Hagen, O., Mo̸rk, K. , Sigurdsson, G. , and Nielsen, F. G., (2003), Evaluation of Free Spanning Pipeline Design in a Risk Based Perspective, Vol. 2 Safety Reliability, Pipeline Technology, vol. 2, p. 789–799##6- Van den Abeele, F. , Boël, F. , and Vanden Berghe, J.-F. , (2014), Structural Reliability of Free Spanning Pipelines, Volume 3: Materials and Joining; Risk and Reliability##7- Shabani, M. M. , Taheri, A., and Daghigh, M., (2017), Reliability Assessment of Free Spanning Subsea Pipeline, Thin-Walled Structures, vol. 120, p. 116–123##8- “DNV-RP-F105: Free Spanning Pipelines, (2006).##9- Wilson, J. F., J.Muga, B., and C.Reese, L., (2003), Dynamics of Offshore Structrues, Second edition. Hoboken, New Jersey: John Wiley & Sons, Inc.,##10- Van den Abeele, F. , Boël, F., and Hill, M., (2013), Fatigue Analysis of Free Spanning Pipelines Subjected to Vortex Induced Vibrations, In Proceedings of the 32rd International Conference on Ocean, Offshore and Arctic Engineering OMAE2013##11- Dowling, N. E. , (2013), Fatigue of Materials: Introduction and Stress-Based Approach,” in Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue, Fourth edition, p. 416–490.##12- DNV GL, (2016 ), DNVGL-RP-C203: Fatigue Design of Offshore Steel Structures, no. DNVGL-RP-C203.##13- Dowling, N. E. , Prasad, K. S., and Narayanasamy, R., (2013), Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue, Editors: K. S. Prasad and R. Narayanasamy, Pearson, pp. 26–30.##14- Fyrileiv, O. , and Kim, M. , (1998), Assessment of Free Spanning Pipelines Using the DNV Guideline, In Proceeding of 8th International Offshore Polar Engenergy Conference, vol. II, p. 100–106.##15- Sollund, H. A. and Vedeld, K., (2015), Effects of Seabed Topography on Modal Analyses of Free Spanning Pipelines, In Proceeding of International Offshore Polar Engergy Conference, pp. 106–114, 2015.##16- Bai, Q. and Bai, Y., (2014 ), Chapter-3: Buckling and Collapse of Metallic Pipes, in Subsea Pipeline Design, Analysis, and Installation, editors: Q. Bai and Y. Bai, Boston: Gulf Professional Publishing, p. 41–65##17- Murphey, C. E., and Langner, C. G. , (1985), Ultimate Pipe Strength Under Bending, Collapse And Fatigue, In Proceedings of the 4th International Conference on Offshore Mechanics and Arctic Engineering, vol. 1, p. 467–477.##18- Gresnigt, A. M. , (1987), Plastic Design of Buried Steel Pipelines in Settlement Areas.##19- Mohareb, M. E. , (1994), deformational Behaviour of Line Pipe, PhD Thesis, Unverisity of Albereta, Canada.##20- Bai, Y. , Tang, J. , Xu, W. , and Ruan, W. , (2015), Reliability-Based Design of Subsea Light Weight Pipeline Against Lateral Stability, Journal of Marine Structures, vol. 43, p. 107–124##21- young, B. , Ranger, I. , and Torgeir, M. , Tube Collapse Under Combined Pressure, Tension And Bending Loads, International Journal of Offshore Polar Engineering, vol. 3, no. 2.##22- STEPHEN, T. , and JAMES, G. , (1963), Theory On Elastic Stability, New Yourk: Mcgraw-Hill Publication, p. 290–300.##23- Haagsma, S. C., and Schaap, D. , (1981), Collapse Resistance of Submarine Lines Studied, Oil Gas Journal, United States, vol. 79.##24- Bai, Y. , and Bai, Q., (2005), Chapter 3: Buckling/Collapse of Deepwater Metallic Pipes, in Subsea Pipelines and Risers, Editors: Y. Bai and Q. Bai, Oxford: Elsevier Science Ltd, p. 41–66.##25- Lee, O. S., Kim, D. H. , and Choi, S. S. , (2006) Reliability of Buried Pipeline Using a Theory of Probability of Failure, Solid State Phenomena, vol. 110, p. 221–230.##26- BOMEL Limited, (2001), Probabilistic Methods: Uses and Abuses in Structural Integrity, in Probabilistic methods: Uses and abuses in structural integrity, no. 398/2001.##27- BOMEL Limited, Structural Reliability Theory, Uncertainty Modelling and the Interpretation of Probability, in Probabilistic methods: Uses and abuses in structural integrity, no. 398/2001, 2001.##28- Der Kiureghian, A., (2005), First- and Second-Order Reliability Methods, in Engineering Design Reliability, Editors: E. Nikolaidis, D. M. Ghiocel, and S. Singhal, ohio: CRC Press, p. 302–325.##29- Mahmoodian, M. , and Li, C. Q. , (2017), Failure Assessment and Safe Life Prediction of Corroded Oil And Gas Pipelines, Journal of Petroleum Science Enginering, vol. 151, p. 434–438.##30- Schuëller, G. I. , and Stix, R. , (1987), A Critical Appraisal of Methods to Determine Failure Probabilities, Structural Safety, vol. 4, no. 4, pp. 293–309.##31- Galgoul, N. S. , Paulino de Barros, J. C. , and Ferreira, R. P., (2004), The Interaction of Free Span And Lateral Buckling Problems, In Proceedings of International Pipeline Conference, Volumes 1, 2, and 3, p. 1905–1910.## ##

Resistance Prediction for a Novel Trimaran with Wave Piercing Bow 2 2 Nowadays, application of high speed crafts with large tonnage is of our country's essences. In order to gain high speed, new multi hull crafts are traditional. A hull form having been used recently in frigates is the Trimaran. Trimaran hull form and motion have been extensively studied due to the development of numerical and analytical methods as well as the exploitation of experimental setup. In this article, we investigate the possibility to move the side hulls longitudinal and transversal with respect to the main hull in order to find the optimum situation for minimum drag. The mathematical approach is numerical method CFD with the help of VOF. Moreover the experimental measurement was provided for some cases. The simulation results indicated good agreement with the experimental results. The investigations undertaken within the scope of this article provide a starting point to investigate the flow pattern and performance of such ships. 33 40 2017/03/172017/05/152017/08/52017/05/13 1396/2/23 2017/11/92017/09/272018/01/82018/02/6 1396/11/17 karim akbari vakilabadi karim akbari vakilabadi Marine Faculty of Imam Khomeini Maritime University iran akbari.karim@gmail.com Mohammadreza khedmai Mohammadreza khedmai Marine Faculty of Amirkabir University of Technology iran khedmai@aut.ac.ir Trimaran Resistance Piercing Bow Experiment Elcin, Z.; (2003), Wave making resistance characteristics of trimaran hulls: Ms Thesis; Naval Postgraduate School, Monterey, California, Available from Internet:##Maki, K.J. et al.; (2007),Resistance Predictions for a High-Speed Sealift Trimaran, 9th Int. Conf. on Numerical Ship Hydrodynamics Ann Arbor, Michigan, Aug. 5-8.##Hebblewhite, K.; Sahoo, P. K.; Doctors, L.J. (2007),A case study: theoretical and experimental analysis of motion characteristics of a trimaran hull form, SAOS Vol. 2 No. 2 pp. 149–156.##Fang, M.C.; Chen, T.Y. (2008),A parametric study of wave loads on trimaran ships traveling in waves, Ocean Engineering 35: 749–762.##Javanmardi, M.R.; Jahanbakhsh, E.; Seif, M.S.; Sayyaadi, H. (2008),Hydrodynamic Analysis of Trimaran Vessels, Polish Maritime Research 1(55) Vol 15; pp. 11-18##Vakilabadi K. A.; Khedmati, M.R.; Seif, M.S. (2014),Experimental Study on Heave and Pitch Motion Characteristics of A Wave-Piercing Trimaran, Transactions of FAMENA 38 (3), 13-26.##Mizine, I.; Karafiath, G.; Queutey, P.; Visonneau, M. (2009),Interference Phenomenon in Design of Trimaran Ship, 10th International Conference on Fast Sea Transportation, FAST, Athens, Greece.##Chong-ben, N.; Ren-chuan, Z.; Guo-ping, M.; Ju, F. (2011),Hull Gesture and Resistance Prediction of High-Speed Vessels, J. of Hydrodynamics, 23(2):234-240.##Bo, Y.; Zuo-chao, W.; Ming, W. (2012),Numerical Simulation of Naval Ship’s Roll Damping Based on CFD, The Second SREE Conference on Engineering Modelling and Simulation, Procedia Engineering 37: 14 – 18, Elsevier. doi:10.1016/j.proeng.2012.04.194##Zeraatgar, H.; Vakilabadi, K.A.; Yousefnejad, R. (2011),Parametric Analysis of Ship Squat in Shallow Water by Model Test, Brodogradnja 62 (1), 37-43.## ##

Mooring Line Reliability Analysis of Single Point Mooring (SPM) System under Extreme Wave and Current Conditions 2 2 Single Point Mooring (SPM) is a type of offshore facility that is used for the loading and unloading of oil and gas tankers in the sea. In Iran, it is briefly called “floating buoy”. The present study discussed floating type, fixed to the seabed with mooring chain. The mooring chain of SPM, which is considered one of the important parameters of its design, will be evaluated with regard to reliability in different environmental conditions. Reliability is the likelihood of a healthy and flawless functionality for a specific time according to existing and predetermined conditions. OrcaFlex Ver. 9.4e (UK) software, by Orcina Company was used for moorings analysis. For this purpose and to calculate the environmental forces in the mooring chains (in our case 6 mooring chains with a 60 degree angle), the researchers used the diffraction analysis and time history. The results revealed that; by decreasing and increasing the diameter of the mooring chain, the force applied to the mooring also decreased and increased, respectively. Also, the effects of chain diameter, direction, and amount of wave and current were studied. The behavior of wave and current showed that when the direction of the wave and the current were closer to the direction of each mooring chain, the force applied to the mooring increased. To calculate the reliability, the FORM method was employed, and to find the target point on the function, the MPP method was used. The reliability of mooring was intended to control, the value of reliability index (β), using a software program written in MATLAB, for the environment loads with a return period of 100 years. The reliability index for mooring lines of SPM was greater than 3.51, representing the safe performance of the mooring lines under environmental load. 41 49 2017/03/172017/05/152017/08/52017/05/132017/10/21 1396/7/29 2017/11/92017/09/272018/01/82018/02/62018/03/18 1396/12/27 Behrouz Eghbali Behrouz Eghbali Department of Marine Structures, Science and Research Branch, Islamic Azad University, Tehran iran b.eghbali@yahoo.com Mohammad Daghigh Mohammad Daghigh Department of Marine Structures, Science and Research Branch, Islamic Azad University, Tehran iran mdaghigh@gmail.com Younes Daghigh Younes Daghigh Department of Marine Structures, Science and Research Branch, Islamic Azad University, Tehran iran daghigh_y@yahoo.com Farhood Azarsina Farhood Azarsina Department of Marine Structures, Science and Research Branch, Islamic Azad University, Tehran iran f.azarsina@srbiau.ac.ir Reliability Moorings Force Floating Buoy SPM OrcaFlex MATLAB Software OGP (2010). Risk Assessment Data Directory – Storage Incident Frequencies.##Faltinsen, O. M., (1990), Sea Loads on Ships and Offshore Structures, Cambridge University Press.##Pecher, A. (2014). "Comparison and Sensitivity Investigations of a CALM and SALM Type Mooring System for Wave Energy Converters." Marine Science and Engineering: 2077-1312.##DNVGL-OS-E301, (2015), Position Mooring. Norway, Det Norske Veritas.##DNVGL-OS-E302 (2015), Offshore Mooring Chain. Norway, Det Norske Veritas.##Du.Xiaoping, (2005), Probabilistic Engineering Design-First Order and Second Reliability Methods, University of Missouri – Rolla. Chapter 7##L.MacCarthy, (2012), Probabilistic Analysis of Indeterminate Highway Bridges Considering Material Nonlinearity. Civil & Structural Engineering, Dublin Institute of Technology, Bolton St, Dublin 1, Ireland.##TehranBerkeley, (2012), SPM Engineering Studies for Azadegan Extra Heavy Crude Oil Export from Bahregan Oil Terminal.## ##

Control of Multiple Underwater Vessels to Converge to a Desired Pattern 2 2 The important and hazardous of the rescue mission in oceans and seas, autonomous vessels now are one of the most appropriate applications among others. Due to safety, reliability, and accessibility of smart, Autonomous and Cooperative vessels today has attracted much attention from the industry. Regard to the complication of the mono vessel for different objects, the multi- agent system was proposed by the researchers. A group of vessels which are connected to each other through different communication systems like GPS, INS and etc., could easily act their duties in the different situations. Design a strategy controller for a group of underwater vessels with the aid of Lyapanove and Graph theory is addressed in this brief. Realistic dynamics is considered in this paper which is novel things in the fields of control system design to demonstrate the performances of the designed controller. Using realistic dynamics makes it possible to really analyze the behavior of the system and consider all the problems which the systems might be faced in reality. The main features of the proposed controller are the decentralized and scalable controller which convert the controller to be applicable to the different number of agents also in the different situation without any external monitoring and this is while all the previous work were based on the external Control. Due to the realistic agent dynamics, non-holonomic dynamics and turning constraints of the vessels are considered in the design process. Advantages of the proposed controller could be represented as follow: domestic information is used between vessels. Based on the realistic dynamics of motion, damping and inertia matrix which in previous works used to be diagonal and constant, are considered as non-diagonal and variable. Also to represent the effectiveness of the proposed controllers, MATLAB and SIMULINK are used to simulate the effectiveness of the controller. As the simulation results show, designed controllers perform well on the system and the objective duty is achieved appropriately. 51 57 2017/03/172017/05/152017/08/52017/05/132017/10/212017/07/3 1396/4/12 2017/11/92017/09/272018/01/82018/02/62018/03/182018/03/15 1396/12/24 Hassan Sayyaadi Hassan Sayyaadi School of Mechanical Engineering, Sharif University of Technology Iran sayyaadi@sharif.edu Abbas Ghassemzadeh Abbas Ghassemzadeh School of Mechanical Engineering, Sharif University of Technology Iran abbas_gh68@hotmail.com Multi agent system Group coordination Swarm Non-Linear control Vessel Dynamics Autonomous control Decentralized control Fiorelli, N. E. L. a. E., (2001), Virtual leaders, artificial potentials and coordinated control of groups, Decision and Control. Orlando, FL, USA, USA, IEEE.##Filippo Arrichiello., S. C., Thor I. Fossen, (2006), Formation Control of Underactuated Surface Vessels using the Null-Space-Based Behavioral Control, Intelligent Robots and Systems. Beijing, China IEEE.##Jagannathan, T. D. a. S., (2007), Control of Nonholonomic Mobile Robot Formations: Backstepping Kinematics into Dynamics. IEEE International Conference on Control Applications. Singapore, Singapore, IEEE.##Hashem Ashrafiuon, K. R. M., Lucas C. McNinch (2008), Sliding-Mode Tracking Control of Surface Vessels, IEEE Transactions on Industrial Electronics 55.##Jevtic, A., Gazi, P., Andina, D., Jamshidi, M., (2010), Building a swarm of robotic bees, World Automation Congress (WAC).##Barış Fidan, V. G., Shaohao Zhai, (2013), Single-View Distance-Estimation-Based Formation Control of Robotic Swarms, IEEE Transactions on Industrial Electronics 60(12).##Gazi, V., (2014), Distributed output agreement in a class of uncertain linear heterogeneous multi-agent dynamic systems, Control Conference (ECC). Strasbourg, France, IEEE.##Dong, W., (2010), Cooperative control of underactuated surface vessels, IET Control Theory & Applications 4(9).##Bishop, B. E., (2012), Formation control of underactuated autonomous surface vessels using redundant manipulator analogs, IEEE International Conference on Robotics and Automation (ICRA),. Saint Paul, MN, USA IEEE.##I.-A.F. Ihle, J. J., T.I. Fossen, (2006), Robust Formation Control of Marine Craft Using Lagrange Multipliers, Springer, Berlin, Heidelberg.##Jan Tommy Gravdahl, K. Y. P., Henk Nijmeijer, (2006), Group Coordination and Cooperative Control, Berlin, Germany, Springer-Verlag Berlin and Heidelberg GmbH & Co. KG##Gazi, V., Passino, Kevin M., (2011), Swarm Stability and Optimization, springer.##Chung, F. R. K., (1997), Spectral Graph Theory, AMS and CBMS.##RussellMerris, (1998), Laplacian graph eigenvectors, Linear Algebra and its Applications 278: 1-7.##W. Dong, J. A. F., (2008), Formation control of multiple underactuated surface vessels, IET Control Theory & Applications 2(12).##Lucas C. McNinch, H. A., (2011), Predictive and sliding mode cascade control for Unmanned Surface Vessels, American Control Conference (ACC), San Francisco, CA, USA IEEE.##Arkin, R. C., (1998), Behavior-Based Robotics MIT Press.##Brooks, R., (1986), A robust layered control system for a mobile robot, IEEE Robotics and Automation Society.##Arkin, R., (1989), Motor schema—based mobile robot navigation, The International journal of robotics research.##Krishnaprasad, E. W. J. a. P. S., (2004), Equilibrium and steering laws for planar formations, IEEE Trans. Robot. Automat 19.##J.R.T. Lawton, R. W. B., B.J. Young, (2003), A decentralized approach to formation maneuvers, IEEE Robotics and Automation Society 19(6).##Joshua A. Marshall, M. E. B., Bruce A. Francis (2006), Pursuit formations of unicycles, Automatica (Journal of IFAC) 42(1).##Zhiyun Lin, B. F., M. Maggiore, (2005), Necessary and sufficient graphical conditions for formation control of unicycles, IEEE Control Systems Society 50(1).## ##