Numerical Simulation of Hydrodynamic Performance of Dolphin Fluke Motion

2018 ◽  
Author(s):  
Rijie Li ◽  
Jiajun Chen ◽  
Yushen Huang ◽  
Liwei Liu ◽  
Xianzhou Wang
Keyword(s):  
Numerical Simulation ◽  
Underwater Vehicle ◽  
Hydrodynamic Performance ◽  
Moving Mesh ◽  
Caudal Fin ◽  
Thrust Generation ◽  
Thrust Characteristics ◽  
Oscillating Motion ◽  
The Relationship ◽  
High Thrust

The dolphins’ cruising, generally, with an extremely high thrust efficiency and low drag, which attracted many researchers’ wide attention. It is hoped that we can improve the hydrodynamic performance of underwater vehicle by studying the thrust characteristics of dolphin’s kick and the relationship between the formation of vortex and the thrust generation. However, previous work is mostly focused on investigation of hydrodynamic performance of dolphin fluke motion with a rigid tail which means that the locomotion of caudal fin is defined only by the oscillating motion, without the chordwise deformation. In this paper, the dolphin’s fluke motion is realized by a flexible caudal fin which is defined by a combination of oscillating motion and chordwise deformation. The simulation of the dolphin fluke motion is achieved by STRA-CCM, and dynamic moving mesh is implemented for different stroke functions. This paper primarily analyzed the thrust characteristics and the formation of vortex of dolphin fluke motion, then compared with the available data from previous work with rigid tail. It can be found that the structure of the vortex generated by the dolphin fluke motion with flexible caudal fin is different from a rigid one. Finally, by analyzing the instantaneous flow condition behind the dolphin caudal fin, it can get the reason why the thrust generated by the flexible caudal fin is larger than rigid one.

Numerical Simulation Study on the Recovery Process of Autonomous Underwater Vehicle

2021 ◽  
Author(s):  
Weigang Huang ◽  
Donglei Zhang ◽  
Jiawei Yu ◽  
Tao He ◽  
Xianzhou Wang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Autonomous Underwater Vehicle ◽  
Flow Characteristics ◽  
Recovery Process ◽  
Underwater Vehicle ◽  
Hydrodynamic Performance ◽  
Time Step ◽  
Convergence Test ◽  
Motion Paths

Abstract AUV (Autonomous Underwater Vehicle) recovery is considerably influenced by the nearby flow field and simulations of AUV in different motion paths in the wake of a submarine with a propeller are presented in this paper. A commercial CFD solver STAR CCM+ has been used to research the motion and flow characteristics of AUV, which using the advanced computational continuum mechanics algorithms. The DARPA (Defense Advanced Research Projects Agency) SUBOFF Submarine (L1 = 4.356m) propelled with INSEAN (Italian Ship Model Basin) E1619 propeller is used in this study, and the self-propulsion characteristics of the propeller at an incoming flow velocity of 2.75m/s are obtained through numerical simulation and results are compared with the available experimental data to prove the accuracy of the chosen investigation methodology. A grid/time-step convergence test is performed for verification study. AUV (L2 = 0.4356m) is a smaller-scale SUBOFF without a sail, which approaches the submarine in different motion paths in the submarine wake at a relative speed combined with the dynamic overlapping grid technology. The hydrodynamic performance of the AUV when approaching the submarine and the velocity distribution of the surrounding flow field are analyzed, which provides a useful reference for underwater recovery of the AUV.

scholarly journals Thrust Characteristics of Ducted Propeller and Hydrodynamics of an Underwater Vehicle in Control Motions

2021 ◽  
Vol 9 (9) ◽  
pp. 940
Author(s):  
Jiaming Wu ◽  
Yizhe Dou ◽  
Haiyan Lv ◽  
Chenghua Ma ◽  
Le Zhong ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Hybrid Algorithm ◽  
Stokes Equations ◽  
Underwater Vehicle ◽  
Flow Fields ◽  
Dynamic Mesh ◽  
Hydrodynamic Performance ◽  
Main Body ◽  
Sliding Mesh ◽  
Ducted Propellers

A numerical technique to simulate the hydrodynamic behavior of ducted propellers attached to an underwater vehicle traveling under the mutually interacting flow fields of the vehicle and the propellers is proposed; the hydrodynamic performance of the propellers and the hydrodynamic loading on the main body of the vehicle when it is in different kinds of motion is investigated numerically. In the research, 3D geometric models of the duct, propeller, and main body of the vehicle are first constructed according to their geometrical features. A computational fluid dynamics (CFD) technique based on the hybrid algorithm of dynamic mesh-nested sliding mesh is applied to solve the Navier–Stokes equations that govern the fluid motion around the duct, propeller, and main body of the vehicle when it is in motion. These equations are solved numerically with the CFD code Fluent. With the proposed numerical simulation technique, the hydrodynamic characteristics of the thrusts generated by the ducted propellers and the loading on the main body in the vehicle system under the mutually interacting flow fields are observed. The results of our numerical simulation indicate that the hybrid algorithm of dynamic mesh-nested sliding mesh can simulate multiple degrees of freedom of motion in underwater vehicle systems. In different motion states, the main body exerts a significant influence on the investigated flow fields; during the vehicle motions, negative wakes are formed on both sides of the main body, which lead to a decrease in the thrusts generated by the propellers on both sides. The thrust of the middle propeller is greater than that of the normal single one because of the obstructing effect in the tunnel caused by the main body.

Hydrodynamic Performance and Appendage Considerations of Wave-Piercing Planing Craft Overlapping Waves and Porpoising

2019 ◽  
Author(s):  
Sang-Won Kim ◽  
Sang-Eui Lee ◽  
Gyoung-Woo Lee ◽  
Kwang-Cheol Seo ◽  
Nobuyuki Oshima
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
High Speed ◽  
Numerical Study ◽  
Hydrodynamic Performance ◽  
Moving Mesh ◽  
Navier Stokes ◽  
Hull Form ◽  
Wave Condition ◽  
Planing Craft

Abstract This work addresses the numerical study of wave-piercing planing hull and related hydrodynamic performance as the appendages. From the half century ago, the interest in high-speed planing crafts has been advanced toward maintaining performance stably. The main reasons to make it hard are instability motion occurring from porpoising and wave condition. Porpoising is mainly due to overlap the heaving and pitching motion with certain period, which is caused by instable pressure distribution and changing longitudinal location of center of gravity. In addition, in wave condition, encountering wave disturbs going into planing mode. This paper presents numerical results of wave-piercing planing hull in porpoising and wave condition. Numerical simulation is conducted via Reynolds Averaged Navier-stokes (RANS) with moving mesh techniques (overset grid), performed at different wave condition. The results for the behaviors of wave-piercing hull form are practically presented and investigated in this study. The understanding of these phenomena is important for design of appendages of wave-piercing hull-form.

Effects of the Launch Speed on Hydrodynamic Force of the Underwater Vehicle Vertical Launch with the Gas Curtain

2012 ◽  
Vol 625 ◽  
pp. 84-87 ◽  
Author(s):  
Hai Jun Liu ◽  
Xing Zhi Peng ◽  
Zhen Zhu Zou
Keyword(s):  
Numerical Simulation ◽  
Hydrodynamic Force ◽  
Underwater Vehicle ◽  
Hydrodynamic Characteristics ◽  
Gravity Effect ◽  
Vof Model ◽  
The Relationship

The vertical launch of the gas curtain is a new underwater launch technology. The gravity effect of the launch speed on hydrodynamic characteristics of the underwater vehicle vertical launching by using the gas curtain has been studied by adopting the multiphase VOF model and the standardturbulence model. The relationship between the launch speed and the shape of the underwater vehicle has been achieved by using the numerical simulation. The relationships between the launch speed and the hydrodynamic characteristics of the underwater vehicle vertically launching from the tube, navigating in water and exiting water have been investigated by using numerical simulation. The hydrodynamic characteristics of underwater vehicle vertical launching by using the gas curtain method are small. The effects of the launch speed on the hydrodynamic characteristics of the underwater vehicle vertical launching in the gas curtain are small.

Numerical Simulation on Hydrodynamic Behaviors of Ducted Propeller in Yawing Motion of an Underwater Vehicle

2015 ◽  
Author(s):  
Jiaming Wu ◽  
Chengwei Zhang ◽  
Zhijian Ye ◽  
Ying Xu ◽  
Weiwen Feng ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Stokes Equations ◽  
Underwater Vehicle ◽  
Integrated System ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Vehicle System ◽  
Ducted Propeller ◽  
Ducted Propellers

A practical approach to simulate hydrodynamic performance of ducted propellers attached in an underwater vehicle under the influence of flow field of the vehicle is proposed, hydrodynamic characteristics of the propeller when the vehicle in a dynamic yawing motion is studied numerically. In the research, 3D geometric models of the duct, propeller and underwater vehicle are first constructed according to their geometrical features. Computational fluid dynamics (CFD) technique based on the finite volume method and multi-sliding mesh technique are applied to solve the Navier-Stokes equations which govern the fluid motions around the duct, propeller and underwater vehicle when the vehicle are in a yawing motion. These equations are solved numerically with the CFD code FLUENT. With the proposed numerical simulation approaches, the hydrodynamic phenomenon of thrusts generated from the ducted propellers in the vehicle system under the flow field influence of the vehicle’s yawing motion are analyzed. Results of our numerical simulation indicate that the influence of flow field caused by the underwater vehicle on the thrusts of the ducted propellers is not negligible; when studying the thrust characteristics of a ducted propeller in an underwater vehicle system, the thrust nature of the propeller can only be evaluated objectively on the condition that the vehicle and the ducted propeller are combined together into an integrated system, and the numerical simulation are conducted in such an integrated system.

NUMERICAL SIMULATION STUDY ON BIONIC MUCUS DRAG REDUCTION OF UNDERWATER VEHICLE

2020 ◽  
Vol 47 (4) ◽  
pp. 371-385
Author(s):  
Kaisheng Zhang ◽  
Chaofan Ma ◽  
Baocheng Zhang ◽  
Bo Zhao ◽  
Qiang Wang
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Simulation Study ◽  
Underwater Vehicle

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

Some Relationship between Safety Factor of Earthquake Slope and Related Parameters

2011 ◽  
Vol 422 ◽  
pp. 688-692
Author(s):  
Xiao Hei He ◽  
Geng You Han ◽  
Rui Hua Xiao
Keyword(s):  
Numerical Simulation ◽  
Rock Mechanics ◽  
Safety Factor ◽  
Limit Equilibrium ◽  
Static Method ◽  
Acceleration Coefficient ◽  
The Wenchuan Earthquake ◽  
Stability Of Slope ◽  
The Stability ◽  
The Relationship

Abstract:Since the Wenchuan earthquake happened, the slope stability had been paid much more attention. The safety factor is an important parameter that can be used to evaluate the stability of slope. The pseudo-static method that based on limit equilibrium and the method of numerical simulation can calculate the safety factor accurately, but the velocity that gets the result is slow. If we can establish the relationship between safety factor and some other parameters, then we can calculate the safety factor by using the relationship more quickly. This paper establishes much relationship, such as the relationship between the rock mechanics parameters and the average danymic safety factor, the relationship between the rock mechanics parameters and the ratio of average danymic safety factor to static safety factor, the relationship between the rock mechanics parameters and the average earthquake acceleration coefficient, the relationship between the average earthquake acceleration coefficient and the ratio of average danymic safety factor to static safety factor, and the relationship between the earthquake acceleration coefficient and the ratio of danymic safety factor to static safety factor on the condition of different rock mass.

scholarly journals Numerical Simulation and Hydrodynamic Performance Predicting of 2 Two-Dimensional Hydrofoils in Tandem Configuration

2021 ◽  
Vol 9 (5) ◽  
pp. 462
Author(s):  
Yuchen Shang ◽  
Juan J. Horrillo
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Resource Constraints ◽  
Lift Coefficient ◽  
Parametric Method ◽  
Experimental Results ◽  
Hydrodynamic Performance ◽  
Tandem Configuration ◽  
Artificial Neural Network Ann ◽  
Naca 0012

In this study we investigated the performance of NACA 0012 hydrofoils aligned in tandem using parametric method and Neural Networks. We use the 2D viscous numerical model (STAR-CCM+) to simulate the hydrofoil system. To validate the numerical model, we modeled a single NACA 0012 configuration and compared it to experimental results. Results are found in concordance with the published experimental results. Then two NACA 0012 hydrofoils in tandem configuration were studied in relation to 788 combinations of the following parameters: spacing between two hydrofoils, angle of attack (AOA) of upstream hydrofoil and AOA of downstream hydrofoil. The effects exerted by these three parameters on the hydrodynamic coefficients Lift coefficient (CL), Drag Coefficient (CD) and Lift-Drag Ratio (LDR), are consistent with the behavior of the system. To establish a control system for the hydrofoil craft, a timely analysis of the hydrodynamic system is needed due to the computational resource constraints, analysis of a large combination and time consuming of the three parameters established. To provide a broader and faster way to predict the hydrodynamic performance of two hydrofoils in tandem configuration, an optimal artificial neural network (ANN) was trained using the large combination of three parameters generated from the numerical simulations. Regression analysis of the output of ANN was performed, and the results are consistent with numerical simulation with a correlation coefficient greater than 99.99%. The optimized spacing of 6.6c are suggested where the system has the lowest CD while obtaining the highest CL and LDR. The formula of the ANN was then presented, providing a reliable predicting method of hydrofoils in tandem configuration.

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