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Only one manuscript as principal or co-author is allowed at a time.</strong></p> en-US <p>Please&nbsp;download the <a title="Copyright Transfer Agreement" href="" target="_self">Copyright Transfer Agreement</a> and&nbsp;send it after duly filled in.</p> <p>Note that <strong>review process will be started</strong> after <strong>recieving the signed agreement</strong>.</p> <p><strong>Now </strong><span style="font-family: Arial,Helvetica;"><strong><a style="font-weight: bold;" title="Refresh your Browser" href="" target="_self">START A NEW SUBMISSION</a> to go to step one of the five-step submission process.</strong> <br></span></p> (Prof. Dr. Md. Mashud Karim) (Md Fahmid Uddin Khondoker) Mon, 31 Dec 2018 15:54:57 +0000 OJS 60 Large eddy simulation of turbulent channel flow using differential equation wall model <p>A large eddy simulation (LES) of a plane turbulent channel flow is performed at a Reynolds number <em>Re<sub>?</sub></em> = 590 based on the channel half width, <em>?</em> and wall shear velocity, <em>u<sub>? </sub></em>by approximating the near wall region using differential equation wall model (DEWM). The simulation is performed in a computational domain of 2?<em>?</em> x 2<em>?</em> x&nbsp;?<em>?</em>. The computational domain is discretized by staggered grid system with 32 x 30 x 32 grid points. In this domain the governing equations of LES are discretized spatially by second order finite difference formulation, and for temporal discretization the third order low-storage Runge-Kutta method is used. Essential turbulence statistics of the computed flow field based on this LES approach are calculated and compared with the available Direct Numerical Simulation (DNS) and LES data where no wall model was used. Comparing the results throughout the calculation domain we have found that the LES results based on DEWM show closer agreement with the DNS data, especially at the near wall region. That is, the LES approach based on DEWM can capture the effects of near wall structures more accurately. Flow structures in the computed flow field in the 3D turbulent channel have also been discussed and compared with LES data using no wall model.</p> Muhammad Saiful Islam Mallik, Md. Ashraf Uddin ##submission.copyrightStatement## Tue, 25 Dec 2018 00:00:00 +0000 CFD investigation on steady and unsteady performances of contra-rotating propellers <p><em>The realistic flow on each blade of the front and rear propellers with contra-rotating propellers (CRPs) are most complex because that consist the interaction forces with themselves and it affects to the actual efficiency of the propeller blades. The wake of CRPs at the gap between the front and rear propellers have influent to the variation of propeller performance for the front and rear propellers. So, this paper presented the numerical simulation of propeller performance on CRPs with steady method in the first. Second, it is applied to evaluate the propeller performance with unsteady method in time accuracy including investigating the wake on a transverse plane between the front and rear propellers and a transverse plane located downstream of the rear propeller. The wake was analyzed through velocity vector magnitude contours. The numerical simulations were conducted using the Reynolds Averaged Navier-Stokes (RANS). The calculation results have been compared the measurement data.</em></p> Prachakon Kaewkhiaw ##submission.copyrightStatement## Wed, 26 Dec 2018 17:42:25 +0000 Study of ramped temperature influence on MHD convective chemically reactive and absorbing fluid past an exponentially accelerated vertical porous plate <p>A systematic study has been performed on MHD convective chemically reactive and absorbing fluid along an exponentially accelerated vertical plate with the impact of Hall current by considering ramped temperature. Laplace transform technique is applied to obtain exact solutions of the non-dimensional governing equations for fluid velocity, temperature and concentration. Based on these solutions, the expressions for skin friction coefficient, Nusselt number and Sherwood number are also derived. The consequences of diverse physical parameters on flow quantities are examined thoroughly with graphical representations. The numerical values for skin friction coefficient, rate of heat transfer and rate of mass transfer are recorded and analyzed.</p> M C Raju, S Harinath Reddy, Dr. E. Keshava Reddy ##submission.copyrightStatement## Sat, 29 Dec 2018 12:15:42 +0000 Design and control of underwater hybrid vehicle capable of performing numerous tasks <p><strong><em>This paper is about Ocean Strider; an Underwater Hybrid Vehicle that is modified with hybrid (manual and autonomous) control system. The aims concerning this Underwater Hybrid Vehicle are to be competent to operate underwater by using remote control via operator and seek out the user interested objects, and in case of autonomously to be smart, to visually follow and manage a secured position comparable to a motionless target, and to visually follow and move behind a moving target and avoid the hindrances for reliable navigation. Vision is a fundamental root that promotes the underwater robot to execute various tasks autonomously. Ocean Strider is intelligent to explicitly identify and locate objects by specifying from distinct color codes and dimension of the objects and respond accordingly.</em></strong> <strong><em>Multiple experiments have been conducted in the laboratory the robot successfully operates manually and grasp the objects underwater, and the robot can locate and track the objects autonomously, secure a fixed distance to the fixed object and travel onward with the object as it moves.&nbsp; &nbsp; &nbsp;&nbsp;</em></strong></p> Kamran Shahani, C. Wu, R. Persaud, H. Song ##submission.copyrightStatement## Sat, 29 Dec 2018 07:00:49 +0000 State space modelling approach for rudder roll stabilization <p>The control objective of the Rudder Roll Stabilization (RRS) system is to deploy the rudder, which is primarily a path controlling device, to reduce the roll motion without interference in heading of ship. To achieve the control of both roll and yaw motions, the only control input is the rudder angle and hence the RRS system is referred as a Single Input, Two Output (SITO) system. Rudder roll stabilization is insignificant at low forward speed of the ship, but can give significant control at higher speed when fast rudder movement is applied. This paper presents a closed loop state space model for accurate simulations on rudder roll stabilization in irregular seas considering the 3-degree of freedom motions, i.e., sway, roll and yaw. The computational model is developed to analyze the effect of the rudder movement on sway, roll and yaw in forward speed conditions in irregular sea conditions. The Sea State conditions are modelled as wave perturbation models using the method of shaping filter established by filtered white noise. The control system has been designed using optimal linear quadratic regulator (LQR) method. The control loop contains both the signal for the autopilot action to trigger the heading angle correction as well as the signal for rudder based roll motion control. The simulations are carried out with rudder roll control system ON and OFF mode to analyze the effect of the rudder on steering and motion stabilization. In both cases the autopilot is in active mode to correct deviations in the course heading. The simulations are analyzed for three different ship speeds in two different Seas State conditions with a low and fast rudder movement to show the efficacy of the model. The performance is evaluated and presented based on the RMS value. Since the rudder based roll motion stabilization may also result in unnecessary motions of sway and yaw, besides the desirable roll reduction, the result presents the sway-roll-yaw responses as applicable under the particular speed and Sea State conditions.</p> BM Shameem, Vinod Vincent ##submission.copyrightStatement## Sun, 30 Dec 2018 17:44:03 +0000