scholarly journals Sensitivity Analysis of the Turning Motion of an Underwater Glider on the Viscous Hydrodynamic Coefficients

2021 ◽  
Vol 71 (5) ◽  
pp. 709-717
Author(s):  
Venkata Shashank Shankar Rayaprolu ◽  
R Vijayakumar
Keyword(s):  
Sensitivity Analysis ◽  
Control Mechanism ◽  
Hydrodynamic Coefficients ◽  
Underwater Glider ◽  
Dynamics Model ◽  
Roll Control ◽  
Underwater Gliders ◽  
Spiral Path ◽  
Viscous Hydrodynamic ◽  
Turning Motion

Autonomous underwater gliders (AUG) are a class of underwater vehicles that move using a buoyancy engine and forces from wings. Gliders execute turning motion with the help of a rudder or an internal roll control mechanism and the trajectory of the turn is a spiral. This paper analyses the sensitivity of the characteristics of spiral manoeuvre on the hydrodynamic coefficients of the glider. Based on the dynamics model of a gliding fish whose turn is enabled by a rudder, the effect of hydrodynamic coefficients of the hull and the rudder on the spiral motion are quantified. Local sensitivity analysis is undertaken using the indirect method. The order of importance of hydrodynamic coefficients is evaluated. It is observed that the spiral path parameters are most sensitive to the side force created by the rudder and the effect of the drag coefficient is predominant to that of the lift coefficients. This study will aid in quantifying the effect of change of geometry on the manoeuvrability of AUGs.

scholarly journals Numerical Study of the Effect of Wing Position on Autonomous Underwater Glider

2020 ◽  
Vol 70 (2) ◽  
pp. 214-220
Author(s):  
R.V. Shashank Shankar ◽  
Rajagopalan Vijayakumar
Keyword(s):  
Numerical Study ◽  
Reynolds Numbers ◽  
Hydrodynamic Characteristics ◽  
Underwater Glider ◽  
Low Reynolds Numbers ◽  
Underwater Gliders ◽  
Turning Motion ◽  
Computational Fluid Dynamics Cfd ◽  
Lift And Drag ◽  
Autonomous Underwater Glider

 Autonomous underwater gliders are a class of underwater vehicles that transit without the help of a conventional propeller. The vehicle uses a buoyancy engine to vary its buoyancy and with the help of the wings attached executes its motion. The hydrodynamic characteristics of the vehicle affect the longitudinal and turning motion. This paper discusses the effect of the wing’s position on the vehicle’s lift and drag characteristics. Computational fluid dynamics (CFD) tool is used to estimate the lift, drag, and pitching moment coefficients of the vehicle. The numerical methodology is validated using flow over NACA0012 wing results for low Reynolds numbers, and the results of CFD are discussed for possible application in estimation of glider motion.

Solar Underwater Glider Robot of Viscous Hydrodynamic Numerical Calculation

2014 ◽  
Vol 487 ◽  
pp. 653-656
Author(s):  
Yu Zhang ◽  
Lei Wang ◽  
Hui Fang Liu
Keyword(s):  
Numerical Calculation ◽  
Theoretical Data ◽  
Data Fitting ◽  
Critical Study ◽  
Underwater Robot ◽  
Hydrodynamic Coefficients ◽  
Underwater Glider ◽  
Hydrodynamic Coefficient ◽  
Ansys Cfx ◽  
Viscous Hydrodynamic

Hydrodynamic coefficients of solar underwater glider robot are one of the important indicators to measure its maneuverability. Based on solar underwater glider robot, using ANSYS CFX software simulate analysis, and through the MATLAB data fitting to body hydrodynamic coefficients. Drawing hydrodynamic coefficient curves for the robot is the critical study of underwater robot hydrodynamics, its shape optimization for subsequent theoretical data is important.

scholarly journals Depth-Average Velocity from Spray Underwater Gliders

2018 ◽  
Vol 35 (8) ◽  
pp. 1665-1673 ◽  
Author(s):  
Daniel L. Rudnick ◽  
Jeffrey T. Sherman ◽  
Alexander P. Wu
Keyword(s):  
Average Velocity ◽  
Dead Reckoning ◽  
Water Velocity ◽  
Accurate Estimation ◽  
Underwater Glider ◽  
Underwater Gliders ◽  
Before And After ◽  
The Difference ◽  
Using Data ◽  
Acoustic Doppler Current Profilers

AbstractThe depth-average velocity is routinely calculated using data from underwater gliders. The calculation is a dead reckoning, where the difference between the glider’s velocity over ground and its velocity through water yields the water velocity averaged over the glider’s dive path. Given the accuracy of global positioning system navigation and the typical 3–6-h dive cycle, the accuracy of the depth-average velocity is overwhelmingly dependent on the accurate estimation of the glider’s velocity through water. The calculation of glider velocity through water for the Spray underwater glider is described. The accuracy of this calculation is addressed using a method similar to that used with shipboard acoustic Doppler current profilers, where water velocity is compared before and after turns to determine a gain to apply to glider velocity through water. Differences of this gain from an ideal value of one are used to evaluate accuracy. Sustained glider observations of several years off California and Palau consisted of missions involving repeated straight sections, producing hundreds of turns. The root-mean-square accuracy of depth-average velocity is estimated to be in the range of 0.01–0.02 m s−1, consistent with inferences from the early days of underwater glider design.

scholarly journals Global Stability of Malaria Transmission Dynamics Model with Logistic Growth

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Abadi Abay Gebremeskel
Keyword(s):  
Sensitivity Analysis ◽  
Global Stability ◽  
Malaria Transmission ◽  
Equilibrium Points ◽  
Transmission Dynamics ◽  
Logistic Growth ◽  
Asymptotically Stable ◽  
Dynamics Model ◽  
Globally Asymptotically Stable ◽  
The Impact

Mathematical models become an important and popular tools to understand the dynamics of the disease and give an insight to reduce the impact of malaria burden within the community. Thus, this paper aims to apply a mathematical model to study global stability of malaria transmission dynamics model with logistic growth. Analysis of the model applies scaling and sensitivity analysis and sensitivity analysis of the model applied to understand the important parameters in transmission and prevalence of malaria disease. We derive the equilibrium points of the model and investigated their stabilities. The results of our analysis have shown that if R0≤1, then the disease-free equilibrium is globally asymptotically stable, and the disease dies out; if R0>1, then the unique endemic equilibrium point is globally asymptotically stable and the disease persists within the population. Furthermore, numerical simulations in the application of the model showed the abrupt and periodic variations.

Cross-Shelf Exchange Associated With the Gulf Stream in the South Atlantic Bight: Direct Observations Using an Autonomous Underwater Glider

2018 ◽  
Vol 52 (3) ◽  
pp. 19-27 ◽  
Author(s):  
Ruoying He ◽  
Austin C. Todd ◽  
Chad Lembke ◽  
Todd Kellison ◽  
Chris Taylor ◽  
...  
Keyword(s):  
Gulf Stream ◽  
Moving Boundary ◽  
South Atlantic ◽  
South Atlantic Bight ◽  
Underwater Glider ◽  
The South ◽  
Underwater Gliders ◽  
Direct Observations ◽  
Autonomous Underwater Glider

AbstractAn autonomous underwater glider was deployed in March 2014 to sample the Gulf Stream and its adjacent shelf waters in the South Atlantic Bight, providing a new look at cross-shelf exchange associated with Gulf Stream dynamics. Observations collected over 4 weeks reveal significant cross-shelf exchange (up to 0.5 Sv) at the shoreward edge of the Gulf Stream, which was 2 orders of magnitude larger than estimates from long-term mean hydrographic conditions. Gulf Stream frontal eddies may have contributed to some of the largest fluxes of heat (0.5°C Sv) and salt (0.03 Sv g/kg) onto the shelf. We estimate that the largest upwelling event during the mission could have brought nitrate concentrations over 20 μM to within 125 m of the surface. This study demonstrates clear capabilities of autonomous underwater gliders for sampling in and near fast moving boundary currents to obtain unique and critical in situ observations effectively.

Hydrodynamic Coefficients and Motion Simulations of Underwater Glider for Virtual Mooring

2013 ◽  
Vol 38 (3) ◽  
pp. 581-597 ◽  
Author(s):  
Masahiko Nakamura ◽  
Kenichi Asakawa ◽  
Tadahiro Hyakudome ◽  
Satoru Kishima ◽  
Hiroki Matsuoka ◽  
...  
Keyword(s):  
Hydrodynamic Coefficients ◽  
Underwater Glider

scholarly journals Numerical Study of the Effect of Wing Position on the Dynamic Motion Characteristics of an Underwater Glider

2021 ◽  
Vol 28 (2) ◽  
pp. 4-17
Author(s):  
Xiangcheng Wu ◽  
Pengyao Yu ◽  
Guangzhao Li ◽  
Fengkun Li
Keyword(s):  
Numerical Study ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Underwater Glider ◽  
Dynamic Motion ◽  
Biological Oceanography ◽  
Underwater Gliders ◽  
Movement Performance ◽  
Motion Characteristics ◽  
The Relationship

Abstract Underwater gliders are winged, autonomous underwater vehicles that are broadly applied in physical and biological oceanography. The position of the wing has an important effect on the movement performance of the underwater glider. In this paper, the dynamic motion of a series of underwater glider models with different longitudinal wing positions are simulated, which provides guidance for the design of underwater gliders. The results show that when the net buoyancy is constant, the wing position affects the gliding angle, but does not affect the relationship between the gliding angle and the gliding speed. In addition, the farther the wing position of the glider is from the buoyancy centre, the longer it takes for the attitude of a glider to change, whether the wing is in front of, or behind, the buoyancy centre.

scholarly journals Design and Motion Simulation of an Underwater Glider in the Vertical Plane

2021 ◽  
Vol 11 (17) ◽  
pp. 8212
Author(s):  
Jiafeng Huang ◽  
Hyeung-Sik Choi ◽  
Dong-Wook Jung ◽  
Ji-Hyeong Lee ◽  
Myung-Jun Kim ◽  
...  
Keyword(s):  
Steady State ◽  
Buoyancy Force ◽  
Vertical Plane ◽  
Power Source ◽  
Motion Simulation ◽  
Underwater Glider ◽  
Simulation Performance ◽  
Underwater Gliders ◽  
Simulation Results ◽  
Sea Currents

Net buoyancy, as the main power source for the motion of an underwater glider, is affected by the pump or bladder that the glider adopts to change its buoyancy force in water. In this study, a new underwater glider that can dive to a depth of 400 m at a cruising speed of 2 knots, which is faster than conventional underwater gliders and is less affected by sea currents, is investigated. The UG resisting 400 m pressure on the buoyancy engine and achieving 2 knots’ speed was designed and constructed. For this UG, its steady-state attitude was studied according to the variance of the buoyancy center and the center of gravity with the buoyancy engine influenced by the displacement of the movable mass block. In motion simulation of the UG, the attitude of the UG under different displacement conditions was simulated in Simulink according to the displacements of the piston and the movable mass block. To validate the simulation performance, a UG was constructed and experiments were conducted. The simulation and experimental results were compared to show the reliability of the simulation results under limited conditions.

scholarly journals Modeling Analysis and Simulation of Viscous Hydrodynamic Model of Single-DOF Manipulator

2019 ◽  
Vol 7 (8) ◽  
pp. 261 ◽  
Author(s):  
Minglu Zhang ◽  
Xiaoyu Liu ◽  
Ying Tian
Keyword(s):  
Hydrodynamic Model ◽  
Theoretical Foundation ◽  
Reference Data ◽  
Control Model ◽  
Hydrodynamic Coefficients ◽  
Precise Control ◽  
Modeling Analysis ◽  
Control Research ◽  
Viscous Hydrodynamic ◽  
Viscous Hydrodynamics

Hydrodynamic modeling is the basis of the precise control research of underwater manipulators. Viscous hydrodynamics, an important part of the hydrodynamic model, directly affects the accuracy of the dynamic model and the control model of the manipulator. Considering the limited research on viscous hydrodynamics of underwater manipulators and the difficulty in measuring viscous hydrodynamic coefficients, the viscous hydrodynamic model in the form of Taylor expansion is analyzed and established. Through carrying out simulation calculations, curve fitting and regression analysis, positional derivatives, rotational derivatives, and coupling derivatives in the viscous hydrodynamic model, are determined. This model provides a crucial theoretical foundation and reference data for subsequent related research.

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