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This paper proposes a formation generation algorithm and formation obstacle avoidance strategy for multiple unmanned surface vehicles (USVs). The proposed formation generation algorithm implements an approach combining a virtual structure and artificial potential field (VSAPF), which provides a high accuracy of formation shape keeping and flexibility of formation shape change. To solve the obstacle avoidance problem of the multi-USV system, an improved dynamic window approach is applied to the formation reference point, which considers the movement ability of the USV. By applying this method, the USV formation can avoid obstacles while maintaining its shape. The combination of the virtual structure and artificial potential field has the advantage of less calculations, so that it can ensure the real-time performance of the algorithm and convenience for deployment on an actual USV. Various simulation results for a group of USVs are provided to demonstrate the effectiveness of the proposed algorithms.
Xun Yan; Dapeng Jiang; Runlong Miao; Yulong Li. Formation Control and Obstacle Avoidance Algorithm of a Multi-USV System Based on Virtual Structure and Artificial Potential Field. Journal of Marine Science and Engineering 2021, 9, 161 .
AMA StyleXun Yan, Dapeng Jiang, Runlong Miao, Yulong Li. Formation Control and Obstacle Avoidance Algorithm of a Multi-USV System Based on Virtual Structure and Artificial Potential Field. Journal of Marine Science and Engineering. 2021; 9 (2):161.
Chicago/Turabian StyleXun Yan; Dapeng Jiang; Runlong Miao; Yulong Li. 2021. "Formation Control and Obstacle Avoidance Algorithm of a Multi-USV System Based on Virtual Structure and Artificial Potential Field." Journal of Marine Science and Engineering 9, no. 2: 161.
The effect of waves on ice sheet is critical in the marginal ice zone (MIZ). Waves break large sea ice into small pieces and cause them to collide with each other. Simultaneously, the interaction between sea ice and waves attenuates these waves. In this study, a numerical research is conducted based on a computational fluid dynamics (CFD) method to investigate the response of single ice floe to wave action. The obtained results demonstrate that the sea ice has a violent six degree of freedom (6DoF) motion in waves. Ice floes with different sizes, thicknesses, and shapes exhibit different 6DoF motions under the action of waves. The heave and surge response amplitude operator (RAO) of the sea ice are related to wavelength. Furthermore, the overwash phenomenon can be observed in the simulation. The obtained results are compared with the model test in the towing tank based on artificial ice, and they agree well with test results.
Tiecheng Wu; Wanzhen Luo; Dapeng Jiang; Rui Deng; Shuo Huang. Numerical Study on Wave-Ice Interaction in the Marginal Ice Zone. Journal of Marine Science and Engineering 2020, 9, 4 .
AMA StyleTiecheng Wu, Wanzhen Luo, Dapeng Jiang, Rui Deng, Shuo Huang. Numerical Study on Wave-Ice Interaction in the Marginal Ice Zone. Journal of Marine Science and Engineering. 2020; 9 (1):4.
Chicago/Turabian StyleTiecheng Wu; Wanzhen Luo; Dapeng Jiang; Rui Deng; Shuo Huang. 2020. "Numerical Study on Wave-Ice Interaction in the Marginal Ice Zone." Journal of Marine Science and Engineering 9, no. 1: 4.
The purpose of this study is to evaluate the ability of the coupled level set and volume of fluid (CLSVOF) method to reproduce violent three-dimensional (3D) free surface deformation induced by different types of dambreak problems. A 3D CLSVOF-based numerical solver is developed, and the finite difference method is adopted to discretize the fluid domain. By applying these methods, the VOF advection equation is solved under the tangent of hyperbola framework to capture the interactions with the weighted linear interface calculation scheme (THINC/WLIC). The OCRWENO scheme is employed to accurately handle the LS advection equation, and the Navier–Stokes equations are discretized by a projection method. For dealing with fluid–structure interactions, the direct forcing immersed boundary method is employed. The developed numerical solver is applied to model free surface evolution in a variety of dambreak experiments. Good agreement is obtained between the numerical simulation and experimental results for each case, thus proving the suitability of the proposed numerical approach for the simulation of violent free surface deformation. The numerical solver developed in this paper has potential for reproducing strongly nonlinear free surface phenomena in other ocean engineering applications.
Y.L. Li; C.P. Ma; X.H. Zhang; K.P. Wang; D.P. Jiang. Three-dimensional numerical simulation of violent free surface deformation based on a coupled level set and volume of fluid method. Ocean Engineering 2020, 210, 106794 .
AMA StyleY.L. Li, C.P. Ma, X.H. Zhang, K.P. Wang, D.P. Jiang. Three-dimensional numerical simulation of violent free surface deformation based on a coupled level set and volume of fluid method. Ocean Engineering. 2020; 210 ():106794.
Chicago/Turabian StyleY.L. Li; C.P. Ma; X.H. Zhang; K.P. Wang; D.P. Jiang. 2020. "Three-dimensional numerical simulation of violent free surface deformation based on a coupled level set and volume of fluid method." Ocean Engineering 210, no. : 106794.
Particle image velocimetry is applied in this study to measure the wake flow field of a Panamax Bulker ship model under the ballast condition. This investigation revealed that the Froude number is 0.167. The time-averaged velocity, turbulent fluctuations, turbulent kinetic energy (TKE), Reynolds stresses, and vorticity information were measured to perform a comparison with the design condition. The time-averaged velocity contours indicated that the ballast and design conditions have distinct hook-like axial velocity contours; however, they appeared at different positions. The big difference under the ballast condition is that the top of the propeller disk area is near the free surface and a region with strong root mean square velocity fluctuation is formed near the free surface. The TKE, the Reynolds stresses, and the hub cap vortex (Hcv) are all affected by the turbulent velocity fluctuation region under the ballast condition. A strong bilge vortex (Bv) is produced when the water flows through the U-shaped stern for the design and ballast conditions.
Tiecheng Wu; Wanzhen Luo; Dapeng Jiang; Rui Deng; Yulong Li. Stereo Particle Image Velocimetry Measurements of the Wake Fields Behind A Panamax Bulker Ship Model Under the Ballast Condition. Journal of Marine Science and Engineering 2020, 8, 397 .
AMA StyleTiecheng Wu, Wanzhen Luo, Dapeng Jiang, Rui Deng, Yulong Li. Stereo Particle Image Velocimetry Measurements of the Wake Fields Behind A Panamax Bulker Ship Model Under the Ballast Condition. Journal of Marine Science and Engineering. 2020; 8 (6):397.
Chicago/Turabian StyleTiecheng Wu; Wanzhen Luo; Dapeng Jiang; Rui Deng; Yulong Li. 2020. "Stereo Particle Image Velocimetry Measurements of the Wake Fields Behind A Panamax Bulker Ship Model Under the Ballast Condition." Journal of Marine Science and Engineering 8, no. 6: 397.
Large propeller lateral loads may be generated under oblique flow condition, which is critical to the safety of stern tube bearing of a ship. In the present study, the effect of oblique flow on propeller lateral loads is numerically investigated based on URANS method, coupled with SST k-ω turbulent model and sliding mesh method. An 82, 000 DWT bulk carrier with a single right-handed screw is computed. Both open water and behind-hull conditions are simulated for a range of drift angles from −20 to 20°. The lateral loads in open water increase with the drift angle increasing in a slightly non-linear trend. However, the behind-hull results are quite different from that in open water. At behind-hull conditions, the horizontal loads monotonously, non-linearly increase as the drift angle increases, while the vertical loads peak at the −5 deg drift angle (corresponding to the transverse flow coming from the portside). In large drift angles, the behind-hull lateral loads reach a larger percentage of the axial loads compared with the open-water results. Scale effect is also investigated by simulating the behind-hull flows with three scales. It is revealed that the increase in scales causes a slight decrease on the horizontal loads independently of drift angles, while it causes a remarkable increase and decrease on the vertical components for positive and negative drift angles, respectively.
Yu-Xin Zhang; Kang Chen; Da-Peng Jiang. CFD analysis of the lateral loads of a propeller in oblique flow. Ocean Engineering 2020, 202, 107153 .
AMA StyleYu-Xin Zhang, Kang Chen, Da-Peng Jiang. CFD analysis of the lateral loads of a propeller in oblique flow. Ocean Engineering. 2020; 202 ():107153.
Chicago/Turabian StyleYu-Xin Zhang; Kang Chen; Da-Peng Jiang. 2020. "CFD analysis of the lateral loads of a propeller in oblique flow." Ocean Engineering 202, no. : 107153.
In present study, high order three dimensional coupled level set and volume of fluid (CLSVOF) based simulations about dam-break induced tsunami bore interacting with the stationary triangular breakwater was numerically investigated. Under our CLSVOF approaching, VOF advection equation is solved by tangent of hyperbola for interface capturing (THINC) with weighed linear interface calculation (WLIC) scheme, and level set advection equation is solved directly by the high-resolution optimized compact reconstruction weighted essentially non-oscillatory (WENO) scheme. Navier-Stokes equations is solved by a projection method on a fixed staggered Cartesian finite difference mesh. The pressure Poisson equation is solved by the point successive over-relaxation (PSOR) method. The direct forcing immersed boundary method (IBM) was implemented for breakwater-tsunami bore interface treatment. Numerical experiments based on our high order 3D CLSVOF-THINC/WLIC-IBM method were carried out in a rectangular water channel with a stationary typical triangular breakwater. The numerical results were compared with corresponding laboratory experimental results and reasonable agreements were obtained with satisfied accuracy. Numerical cases with different shape of triangular breakwater are carried out then in order to investigate the free surface evolution and energy dissipation due to the breakwater and useful conclusion is obtained.
Y.L. Li; Y. Ma; R. Deng; D.P. Jiang; Z. Hu. Research on dam-break induced tsunami bore acting on the triangular breakwater based on high order 3D CLSVOF-THINC/WLIC-IBM approaching. Ocean Engineering 2019, 182, 645 -659.
AMA StyleY.L. Li, Y. Ma, R. Deng, D.P. Jiang, Z. Hu. Research on dam-break induced tsunami bore acting on the triangular breakwater based on high order 3D CLSVOF-THINC/WLIC-IBM approaching. Ocean Engineering. 2019; 182 ():645-659.
Chicago/Turabian StyleY.L. Li; Y. Ma; R. Deng; D.P. Jiang; Z. Hu. 2019. "Research on dam-break induced tsunami bore acting on the triangular breakwater based on high order 3D CLSVOF-THINC/WLIC-IBM approaching." Ocean Engineering 182, no. : 645-659.
The goal of this manuscript is to investigate the influence of relative distance between the twin rotors on the hydrodynamic performance of the vertical axis twin-rotor tidal current turbine. Computational fluid dynamics (CFD) simulations based on commercial software ANSYS-CFX have been performed to enhance the understanding of interactions between the twin-rotors. The interactions between the twin rotors are known to have increased the power output efficiency as a whole, and it is, therefore, of great significance to undertake deeper research. The simulation results are found to be consistent with similar research results in the literature in some aspects. The simulation results of stand-alone turbine and twin rotors are compared from three different aspects, including blade forces, power output efficiency and wake flow field. The results showed that the cyclic variations tendency of blade force coefficients of twin rotors is close to that of the stand-alone turbine. The average power output efficiency of the twin-rotors system is higher than that of the stand-alone turbine. The interactions between the turbines increase the power output of the twin turbine system as whole in a wide relative distance range. However, smaller relative distance between the twin rotors does not mean a bigger power output efficiency of such a system. The power out efficiency of such a system would decrease when the relative distance between the twin rotors exceeds the critical point. The power output of the twin rotors reaches the peak value when the ratio between the two main axis distance and diameter of the turbine is around 9/4. This research can provide a reference for the design and development of larger tidal power stations.
Yong Ma; Chao Hu; Yulong Li; Lei Li; Rui Deng; Dapeng Jiang. Hydrodynamic Performance Analysis of the Vertical Axis Twin-Rotor Tidal Current Turbine. Water 2018, 10, 1694 .
AMA StyleYong Ma, Chao Hu, Yulong Li, Lei Li, Rui Deng, Dapeng Jiang. Hydrodynamic Performance Analysis of the Vertical Axis Twin-Rotor Tidal Current Turbine. Water. 2018; 10 (11):1694.
Chicago/Turabian StyleYong Ma; Chao Hu; Yulong Li; Lei Li; Rui Deng; Dapeng Jiang. 2018. "Hydrodynamic Performance Analysis of the Vertical Axis Twin-Rotor Tidal Current Turbine." Water 10, no. 11: 1694.