Numerical Simulation of Bionic Locomotor Batoid with Combined Frequency Undulating Pectoral Fins

2013 ◽  
Vol 364 ◽  
pp. 346-351
Author(s):  
Zhi Jun Wu ◽  
Wei Shan Chen ◽  
Sheng Jun Shi ◽  
Dan Xia
Keyword(s):  
Numerical Simulation ◽  
Rigid Body ◽  
Frequency Conversion ◽  
Uniform Thickness ◽  
Propulsive Efficiency ◽  
Hydrodynamic Analysis ◽  
Pectoral Fins ◽  
Fin Ray ◽  
Simulation Results ◽  
Motion Design

Batoids propel themselves forward by generating waves along their large pectoral fins. According to the observation of batoids in nature, the frequency of the wave on the pectoral fins is not always invariable. The bionic batoid is composed of rigid body and flexible pectoral fins of uniform thickness. In this study the hydrodynamic analysis of bionic batoid with combined frequency specified on the pectoral fins are presented. The combined frequency is implemented by the frequency conversion during the oscillation of each pectoral fin ray. Since oscillating frequency of 2.2Hz is mostly observed in rajiform batoid, the variable frequencies ranging from 1.0Hz to 2.6Hz with 0.4Hz increment compound 2.2Hz and formed five different sets of combined frequency. The simulation results illustrate that the bionic batoid model with combined frequency locomotion can achieve better propulsive efficiency, which maybe benefit for the motion design of bionic robot batoid.

Experimental Study on a New Suction Inlet Realizable for Uniform Thickness Collection

2011 ◽  
Vol 308-310 ◽  
pp. 1609-1613
Author(s):  
Si Lin Chen ◽  
Xu Dong Yang ◽  
Shi Qiu ◽  
Chun Lin Ma ◽  
Tao Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Rake Angle ◽  
External Flow ◽  
Test Results ◽  
Uniform Thickness ◽  
Bulk Materials ◽  
Work Surface ◽  
Simulation Results ◽  
Calculation Software

The numerical simulation of flow field of a new rectangular suction inlet installing guide plates with different rake angles was carried out by means of the K-ε turbulence model based on the Fluent hydromechanics calculation software. And that the influences of different rake angles of the internal guide plates on the flow field were analyzed. Consequently, the optimal rake angle of 45° was defined at last. Finally, the practical rectangle suction inlet, according to the numerical simulation results, was developed by installing internal guide plates with the optimal rake angle, which optimizes the distribution of internal and external flow field and improves the average side velocities of flow. Practical test results indicate that the new rectangular suction inlet could realize the uniform thickness collection to achieve the smooth work surface when collecting the bulk materials.

An Observer for Rigid Body Motion With Almost Global Finite-Time Convergence

2014 ◽  
Author(s):  
Amit K. Sanyal ◽  
Maziar Izadi ◽  
Jan Bohn
Keyword(s):  
Numerical Simulation ◽  
Rigid Body ◽  
Finite Time ◽  
The Body ◽  
Measurement Noise ◽  
Body Motion ◽  
Nonlinear Observer ◽  
Control Force ◽  
Finite Time Convergence ◽  
Simulation Results

An observer that obtains estimates of the translational and rotational motion states for a rigid body under the influence of known forces and moments is presented. This nonlinear observer exhibits almost global convergence of state estimates in finite time, based on state measurements of the rigid body’s pose and velocities. It assumes a known dynamics model with known resultant force and resultant torque acting on the body, which may include feedback control force and control torque. The observer design based on this model uses the exponential coordinates to describe rigid body pose estimation errors on SE(3), which provides an almost global description of the pose estimate error. Finite-time convergence of state estimates and the observer are shown using a Lyapunov analysis on the nonlinear state space of motion. Numerical simulation results confirm these analytically obtained convergence properties for the case that there is no measurement noise and no uncertainty (noise) in the dynamics. The robustness of this observer to measurement noise in body velocities and additive noise in the force and torque components is also shown through numerical simulation results.

scholarly journals Hydrodynamic Analysis of KVLCC2 Ship Sailing near Inclined Banks

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Weilin Luo ◽  
Bing Yang ◽  
Yafeng Sun
Keyword(s):  
Numerical Simulation ◽  
Unstructured Grid ◽  
Transverse Force ◽  
Hydrodynamic Characteristics ◽  
Bank Angle ◽  
Hydrodynamic Analysis ◽  
Drift Angle ◽  
Tetrahedral Grid ◽  
Simulation Results ◽  
Yaw Moment

The hydrodynamic forces of KVLCC2 ship sailing near inclined banks are calculated by using CFD based on RANS equation. Corresponding CFD uncertainty analysis is conducted according to the procedure recommended by ITTC. An unstructured grid, tetrahedral grid, is employed for discretization. To control the number of grids, global element scale factor is selected as the same as refinement ratio. In numerical simulation, straightforward and oblique navigation conditions are investigated. The variation of transverse force and yaw moment with the ship-shore distance, bank angle, water depth, and drift angle are analyzed. Both hull model and hull-propeller-rudder model are considered in numerical simulation. The simulation results show the hydrodynamic characteristics of ship sailing near inclined banks.

Attitude Control of Rigid Body Using Sliding Mode Control

2011 ◽  
Vol 383-390 ◽  
pp. 7550-7555
Author(s):  
Hui Hui Bian ◽  
Zhong Hua Wang
Keyword(s):  
Numerical Simulation ◽  
Sliding Mode Control ◽  
Rigid Body ◽  
Attitude Control ◽  
Sliding Mode ◽  
Sliding Mode Controller ◽  
Mode Control ◽  
Modified Rodrigues Parameters ◽  
Simulation Results

In this paper, a sliding mode controller is developed based on the modified rodrigues parameters. Modified rodrigues parameters can avoid the singularity in kinematic equations and realize less parameters setting. Finally, the numerical simulation results show that the method is effective.

Avalanche Features in Silicon Schottky-FETs in Accordance with Numerical Simulation Results

2006 ◽  
Vol 65 (16) ◽  
pp. 1533-1546
Author(s):  
Yu. Ye. Gordienko ◽  
S. A. Zuev ◽  
V. V. Starostenko ◽  
V. Yu. Tereshchenko ◽  
A. A. Shadrin
Keyword(s):  
Numerical Simulation ◽  
Simulation Results

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.

scholarly journals Experiment and simulation about the effect of wear-ring abrasion on the performance of a marine centrifugal pump

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199811
Author(s):  
Wu Xianfang ◽  
Du Xinlai ◽  
Tan Minggao ◽  
Liu Houlin
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Velocity ◽  
Test Results ◽  
Obvious Effect ◽  
Performance Change ◽  
Pump Test ◽  
Simulation Results ◽  
Axis Passing

The wear-ring abrasion can cause performance degradation of the marine centrifugal pump. In order to study the effect of front and back wear-ring clearance on a pump, test and numerical simulation were used to investigate the performance change of a pump. The test results show that the head and efficiency of pump decrease by 3.56% and 9.62% respectively at 1.0 Qd due to the wear-ring abrasion. Under 1.0 Qd, with the increase of the front wear-ring the vibration velocity at pump foot increases from 0.4 mm/s to 1.0 mm/s. The axis passing frequency (APF) at the measuring points increases significantly and there appears new characteristic frequency of 3APF and 4APF. The numerical simulation results show that the front wear-ring abrasion affects the flow at the inlet of the front chamber of the pump and impeller passage. And the back wear-ring abrasion has obvious effect on the flow in the back chamber of the pump and impeller passage, while the multi-malfunction of the front wear-ring abrasion and back wear-ring abrasion has the most obvious effect on the flow velocity and flow stability inside pump. The pressure pulsation at Blade Passing Frequency (BPF) of the three schemes all decrease with the increase of the clearance.

scholarly journals Development of Depth-Limited Wave Boundary Layers over a Smooth Bottom

2020 ◽  
Vol 9 (1) ◽  
pp. 27
Author(s):  
Hitoshi Tanaka ◽  
Nguyen Xuan Tinh ◽  
Xiping Yu ◽  
Guangwei Liu
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Boundary Layers ◽  
Wave Motion ◽  
Numerical Study ◽  
Experiment Data ◽  
Tidal Motion ◽  
Long Period ◽  
Simulation Results ◽  
Wave Boundary

A theoretical and numerical study is carried out to investigate the transformation of the wave boundary layer from non-depth-limited (wave-like boundary layer) to depth-limited one (current-like boundary layer) over a smooth bottom. A long period of wave motion is not sufficient to induce depth-limited properties, although it has simply been assumed in various situations under long waves, such as tsunami and tidal currents. Four criteria are obtained theoretically for recognizing the inception of the depth-limited condition under waves. To validate the theoretical criteria, numerical simulation results using a turbulence model as well as laboratory experiment data are employed. In addition, typical field situations induced by tidal motion and tsunami are discussed to show the usefulness of the proposed criteria.

Design of Impeller of Centrifugal Compressor for Water-Air Engine

2014 ◽  
Vol 496-500 ◽  
pp. 642-645
Author(s):  
Yun Wang ◽  
Wei Zhang
Keyword(s):  
Numerical Simulation ◽  
Power System ◽  
Centrifugal Compressor ◽  
Centrifugal Impeller ◽  
3D Design ◽  
Pump Impeller ◽  
Aero Engine ◽  
Simulation Results

In view of power system in water-air UAV requirements, combine with the centrifugal impeller for aero-engine and the pump impeller. The design of a impeller of centrifugal compressor can work on the air and in the water for the new concept of air-water engine. With 3D design and a 3D CFD solver on it and analysis the results of numerical simulation. Results show that the designed impeller successfully reached the goal on the air and in the water. The experiences accumulated in this procedure are useful for similar impeller aerodynamic designs.

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