The Oscillation of Slender Elliptical Inviscid and Newtonian Jets: Effects of Surface Tension, Inertia, Viscosity, and Gravity

1989 ◽  
Vol 56 (4) ◽  
pp. 968-974 ◽  
Author(s):  
S. E. Bechtel
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Cross Section ◽  
Nonlinear Oscillator ◽  
Major Axis ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Fully Nonlinear ◽  
Single Degree ◽  
Elliptical Jet

The motion of inviscid and Newtonian jets issuing from elliptical orifices is analyzed. The analysis is not confined to small departures of the jet free surface from a circular cylindrical mean surface, but rather is fully nonlinear. Two types of behavior are predicted: (1) In the presence of surface tension the major axis of the elliptical jet cross-section alternates between perpendicular directions with distance down the jet. In this case the system is described as a single-degree-of-freedom nonlinear oscillator, conservative for the inviscid elliptical jet in the absence of gravity, and nonconservative for the Newtonian jet. (2) When surface tension is neglected, the transformation occurs only once, after which the jet flattens into a sheet perpendicular to the major axis of the orifice. The effect of gravity is discussed both for downward flowing jets and fountains.

Study on Applicability of Equivalent Single Degree of Freedom Methods for Single Column Pier with Uniform Cross Section

2011 ◽  
Vol 255-260 ◽  
pp. 1716-1720
Author(s):  
Liang Chen
Keyword(s):  
Cross Section ◽  
Fundamental Mode ◽  
Degree Of Freedom ◽  
Mass Ratio ◽  
Shape Functions ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Single Column ◽  
Simplified Method ◽  
Uniform Cross Section

Applicability of the simplified method based on equivalent single-degree-of-freedom (ESDOF) for single-column pier with uniform cross-section is investigated in this paper. The modal participating mass ratio of pier’s fundamental mode is taken as an index to evaluate the applicability of the simplified method. Based on the fundamental mode shape functions selected deliberately in the first step, equations to evaluate the modal participating mass ratio of pier fundamental mode is obtained. Using the proposed equations, it is convenient to evaluate applicability of the simplified method with the height of the pier and the ratio of the linear mass along the column to the dumped mass at the top of the pier. Finally, the index is verified in the different nonlinear range of piers.

Subharmonic resonance of single-degree-of-freedom piecewise-smooth nonlinear oscillator

2020 ◽  
Vol 36 (5) ◽  
pp. 1109-1118
Author(s):  
Jiangchuan Niu ◽  
Wenjing Zhang ◽  
Yongjun Shen ◽  
Shaopu Yang
Keyword(s):  
Nonlinear Oscillator ◽  
Piecewise Smooth ◽  
Subharmonic Resonance ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree

scholarly journals A Kinematic Controller for Liquid Pouring between Vessels Modelled with Smoothed Particle Hydrodynamics

2019 ◽  
Vol 9 (23) ◽  
pp. 5007 ◽  
Author(s):  
Camporredondo ◽  
Barber ◽  
Legrand ◽  
Muñoz
Keyword(s):  
Free Surface ◽  
Real Time ◽  
Smoothed Particle Hydrodynamics ◽  
Initial Phase ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Sph Simulation

In robotics, the task of pouring liquids into vessels in non-structured or domestic spaces is an open field of study. A real time, fluid dynamic simulation, based on smoothed particle hydrodynamics (SPH), together with solid motion kinematics, allow for a closed loop control of pouring. In the first place, a control criterion related with the behavior of the liquid free surface is established to handle sloshing, especially in the initial phase of pouring to prevent liquid adhesion over the vessel rim. A 2-D, free surface SPH simulation is implemented on a graphic processing unit (GPU) to predict the liquid motion with real-time capability. The pouring vessel has a single degree of freedom of rotation, while the catching vessel has a single degree of freedom of translation, and the control loop handles the tilting angle of the pouring vessel. In this work, a two-stage pouring method is proposed, differentiating an initial phase where sloshing is particularly relevant, and a nearly constant outflow phase. For control purposes, the free outflow trajectory was simplified and modelled as a free falling solid with an initial velocity at the vessel crest, as calculated by the SPH simulation. As the first stage of pouring is more delicate, a novel slosh induction method (SIM) is proposed to overcome spilling issues during initial tilting in full filled vessels. Both robotic control and fluid modelling showed good results at multiples initial vessel filling heights.

Kinematic comparison of single degree-of-freedom robotic gait trainers

2021 ◽  
Vol 159 ◽  
pp. 104258
Author(s):  
Jeonghwan Lee ◽  
Lailu Li ◽  
Sung Yul Shin ◽  
Ashish D. Deshpande ◽  
James Sulzer
Keyword(s):  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Robotic Gait
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