scholarly journals Study of the Planar Rocking-Block Dynamics With Coulomb Friction: Critical Kinetic Angles

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Hongjian Zhang ◽  
Bernard Brogliato ◽  
Caishan Liu
Keyword(s):  
Numerical Simulations ◽  
Coulomb Friction ◽  
Numerical Scheme ◽  
Numerical Results ◽  
Experimental Results ◽  
Restitution Coefficient ◽  
Rocking Block ◽  
Kinetic Angle ◽  
Multiple Impact ◽  
Impact With Friction

The objective of this paper is to show, through the planar rocking block example, that kinetic angles play a fundamental role in multiple impact with friction. Even in the presence of Coulomb friction, a critical kinetic angle θcr is exhibited that allows one to split the blocks into two main classes: slender blocks with a kinetic angle larger than θcr, and flat blocks with a kinetic angle smaller than θcr. The value of θcr varies with the friction value, but it is independent of the restitution coefficient (normal dissipation). Numerical results are obtained using a multiple impact law recently introduced by the authors. Some comparisons between numerical and experimental results that validate the used model and numerical scheme are presented. However, this paper is mainly based on numerical simulations.

scholarly journals Theoretical and experimental analysis of the exact receptance function of a clamped-clamped beam with concentrated masses

2020 ◽  
Author(s):  
Nguyen Viet Khoa ◽  
Dao Thi Bich Thao
Keyword(s):  
Dynamic Response ◽  
Numerical Simulations ◽  
Experimental Analysis ◽  
Arbitrary Point ◽  
Peak Position ◽  
Numerical Results ◽  
Experimental Results ◽  
Harmonic Force ◽  
Concentrated Masses

This paper establishes the exact receptance function of a clamped-clamped beam carrying concentrated masses. In this paper, the derivation of exact receptance and numerical simulations are provided. The proposed receptance function is convenient to apply for predicting the dynamic response at arbitrary point of the beam acted by a harmonic force applied at arbitrary point. The influence of the concentrated masses on the receptance is investigated. The numerical simulations show that a peak in the receptance decreases when there is a mass located close to that peak position. The numerical results have been compared to the experimental results has to justify the theory.

Numerical Analysis of Oil/water Dispersion Interface Prediction in Horizontal Pipe Separators

2021 ◽  
Author(s):  
Srinivas Swaroop Kolla ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Numerical Simulations ◽  
Volume Fraction ◽  
Water Layer ◽  
Numerical Results ◽  
Experimental Results ◽  
Internal Diameter ◽  
Ansys Fluent ◽  
Horizontal Pipe ◽  
Water Dispersion ◽  
Vof Model

Abstract This paper presents the comparative study of experimental, modeling, and simulation results that are performed using commercially available ANSYS Fluent software to analyze the separation kinetics of oil and water in a horizontal separator at various velocities and watercuts. The horizontal pipe separator used in this study has an internal diameter of 0.0762 m and a length of 10.3 m separating oil and water with specific gravities of 1.0 and 0.857 and watercuts ranging from 20 to 90%. The mixture velocities studied are 0.08, 0.13, and 0.20 m/s. Numerical simulations are done using the hybrid Eulerian-Eulerian multifluid VOF model to study the effect of watercut on the creaming of the oil layer and sedimentation of the water layer respectively. As the mixture velocities increased, the initial length of separation increased like experimental results. As the watercut increased, the separation of water enhanced, while the oil creaming improved with the lowering of the watercut as expected. Numerical results showed good agreement for water/dispersion interface predictions for all the conditions studied. The CFD results are compared against experimental results obtained by Othman in 2010 and agree with the trend of separation. The numerical simulations gave insights into the velocity profiles in each of the layers such as creamed oil, sedimented water, and the layer of emulsion that is not separated. Also, the numerical results are validated against the extended Gassies (2008) model incorporating correlation for turbulent time decay and oil volume fraction proposed by Dabirian et al in 2018.

scholarly journals A FARM OF WAVE ACTIVATED BODIES FOR COASTAL PROTECTION PURPOSES

2012 ◽  
Vol 1 (33) ◽  
pp. 68 ◽  
Author(s):  
Elisa Angelelli ◽  
Barbara Zanuttigh
Keyword(s):  
Numerical Modelling ◽  
Numerical Simulations ◽  
Transmission Coefficient ◽  
Wave Energy ◽  
Numerical Results ◽  
Experimental Results ◽  
Coastal Protection ◽  
Basic Module ◽  
Wave Energy Converters ◽  
Mike 21

This paper aims at investigating the efficacy of a floating farm of wave energy converters for coastal protection purposes through physical and numerical modelling. The experiments were performed in 3D conditions on a basic module consisting of two staggered lines and three devices. The numerical simulations were carried out with the software MIKE 21 BW, developed by DHI Water & Environment & Health, and were calibrated based on the experimental results. Additional configurations were tested by varying the gap long-shore width and the device alignment. Despite the model limitations, i.e. the representation of the devices as fixed porous piles, the numerical results well approximate the average measured transmission coefficient and allow to derive a complete map of the hydrodynamics around the devices.

Numerical Analysis of the Influence of the Padding-Plate on the Extended End-Plate Connection

2014 ◽  
Vol 578-579 ◽  
pp. 505-508
Author(s):  
Shao Qin Zhang ◽  
Lei Wu
Keyword(s):  
Numerical Analysis ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Load Capacity ◽  
Numerical Results ◽  
Experimental Results ◽  
End Plate ◽  
Extended End Plate ◽  
Plate Connection

In the present paper, we investigate the effect of a padding-plate on the behavior of extended end-plate semi-rigid connections. The numerical simulations were carried out for a standard extended end-plate connection joint without padding-plate and two connection joints with 4mm and 6mm thick padding-plates. The existing experimental results verified the validity of the numerical model. The numerical results have shown that a thin padding-plate will more or less decline the carrying load capacity of the connection joint but greatly improve the connect ductility. Filling a thin padding-plate in the end-plate connection is feasible and brings the forewarning function.

scholarly journals Modeling and analysis of impact based on numerical and experimental approaches

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881306
Author(s):  
Xupeng Wang ◽  
Yan Zhang ◽  
Zhu Gao ◽  
Xiaomin Ji ◽  
Lin Li
Keyword(s):  
Mechanical System ◽  
Contact Force ◽  
Impact Force ◽  
Numerical Results ◽  
Experimental Results ◽  
Force Model ◽  
Restitution Coefficient ◽  
Contact Force Model ◽  
Improved Model ◽  
The Impact

Impact is a universal phenomenon and has serious influences on the dynamic characteristics of mechanical system, so it is critical to accurately describe the effects of impact. In this work, a numerical and comprehensive method is presented to calculate the impact force in clearance joint during impact process, which has higher effectiveness and accuracy than the most popular used L-N model. Different from traditional contact models, where the coefficient of restitution is assumed to be a constant value nearly to 1 during impact process, the improved model in this work sets up the model of restitution coefficient related to two important parameters for impact phenomenon, which are initial impact velocity and the yield strength of the materials in clearance joints. A great number of numerical and experimental results are introduced and compared to validate the improved contact force model; it needs to be highlighted that the numerical results are based on the improved model and the most popular impact force model presented by Lankarani and Nikravesh, and the experimental results are based on two typical pendulum experimental test rigs. It can be concluded that (1) when compared to the experimental results, the numerical results based on the improved model are in better agreement than those based on Lankarani and Nikravesh impact force model; (2) the numerical results based on the improved model are in reasonable agreement with the experimental results, and the relative errors of impact force and restitution coefficient are all no more than 10% between numerical and experimental results; and (3) the improved contact force model is effective and can exactly describe the impact effects between two bodies in mechanical system.

Numerical Simulations of Sloshing in Rectangular Tanks

2006 ◽  
Author(s):  
Samuel R. Ransau ◽  
Ernst W. M. Hansen
Keyword(s):  
Numerical Simulations ◽  
Small Amplitude ◽  
Three Dimensional ◽  
Numerical Results ◽  
Experimental Results ◽  
Non Linear ◽  
Forced Excitation

Simulations of two- and three-dimensional sloshing in rectangular tanks are performed using the commercial CFD code FLOW3D. Small amplitude freely oscillating sloshing and non-linear sloshing due to forced excitation were investigated. The results are compared to both experimental results and other numerical results; and tests are made with different grids. The purpose of this study was the validation of the new VOF algorithm under development at Flow Science and implemented in FLOW3D.

scholarly journals Numerical Simulations of Advanced Transonic Compressor Stages Using an Unsteady Quasi-Three-Dimensional Flow Solver

1995 ◽  
Author(s):  
Gerald J. Micklow ◽  
J. Paul Sauve ◽  
Karthikeyan Shivaraman
Keyword(s):  
Numerical Simulations ◽  
Numerical Scheme ◽  
Stokes Equations ◽  
Computing Time ◽  
Three Dimensional ◽  
Axial Flow ◽  
Numerical Results ◽  
Compressor Stage ◽  
Transonic Compressor ◽  
Exact Geometry

This study presents the results of numerical simulations of single stage transonic axial-flow compressors. The numerical scheme used solves the unsteady quasi-three-dimensional thin-layer Navier-Stokes equations. In the first part of the study, the validation of the numerical scheme for advanced transonic axial-flow compressor stages is presented. The results of a numerical simulation are compared to an experimentally tested transonic compressor stage of DFVLR. Further simulations are performed on an advanced transonic compressor stage design to investigate the effect of airfoil geometry re-scaling, in order to save computing time, on the numerical results. Two cases are simulated: a modified geometry where less stator blades are simulated and an exact geometry where the exact geometry is modeled. Good agreement is obtained between the experimental and numerical results for the first test case, indicating the validity of the quasi-three dimensional method. The last two simulations show that any significant re-scaling of the stage geometry will have an adverse effect on overall results. All of the simulations show that the unsteady rotor-stator interactions have a significant effect on stage performance.

Experimental results on synchronization times and stable states in locally coupled light-controlled oscillators

2009 ◽  
Vol 367 (1901) ◽  
pp. 3267-3280 ◽  
Author(s):  
Nicolas Rubido ◽  
Cecilia Cabeza ◽  
Arturo C. Martí ◽  
Gonzalo Marcelo Ramírez Ávila
Keyword(s):  
Numerical Simulations ◽  
Coupling Strength ◽  
Coupled Oscillators ◽  
Initial Conditions ◽  
Experimental Studies ◽  
Numerical Results ◽  
Experimental Results ◽  
Stable States ◽  
Relaxation Oscillators ◽  
Local Coupling

Recently, a new kind of optically coupled oscillators that behave as relaxation oscillators has been studied experimentally in the case of local coupling. Even though numerical results exist, there are no references about experimental studies concerning the synchronization times with local coupling. In this paper, we study both experimentally and numerically a system of coupled oscillators in different configurations, including local coupling. Synchronization times are quantified as a function of the initial conditions and the coupling strength. For each configuration, the number of stable states is determined varying the different parameters that characterize each oscillator. Experimental results are compared with numerical simulations.

Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV

2018 ◽  
Vol 55 (4) ◽  
pp. 652-657 ◽  
Author(s):  
Gabriel Murariu ◽  
Razvan Adrian Mahu ◽  
Adrian Gabriel Murariu ◽  
Mihai Daniel Dragu ◽  
Lucian P. Georgescu ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Unmanned Aerial Vehicle ◽  
Numerical Study ◽  
Flight Time ◽  
Cluster System ◽  
Numerical Results ◽  
Operational Performance ◽  
Gliding Flight ◽  
Aerial Vehicle ◽  
Constant Altitude

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.

Experimental and numerical investigations on a high-density polyethylene (HDPE) blown film cooling with a new design of the counter-flow/radial jet air-ring

2021 ◽  
pp. 875608792110260
Author(s):  
ME Ismail ◽  
MM Awad ◽  
AM Hamed ◽  
MY Abdelaal ◽  
EB Zeidan
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Film Cooling ◽  
Radiation Heat Transfer ◽  
Absolute Error ◽  
Numerical Results ◽  
Upper Lip ◽  
Original Design ◽  
Blown Film ◽  
Set Up

This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.

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