scholarly journals Proximal bodies in hypersonic flow

2007 ◽  
Vol 590 ◽  
pp. 209-237 ◽  
Author(s):  
STUART J. LAURENCE ◽  
R. DEITERDING ◽  
G. HORNUNG
Keyword(s):  
Numerical Simulations ◽  
Force Measurement ◽  
Lateral Displacement ◽  
Relative Size ◽  
Lateral Force ◽  
Three Dimensions ◽  
Experimental Simulation ◽  
Force Coefficient ◽  
Primary Body ◽  
Two Bodies

Hypersonic flows involving two or more bodies travelling in close proximity to one another are encountered in several important situations. The present work seeks to explore one aspect of the resulting flow problem by investigating the forces experienced by a secondary body when it is within the domain of influence of a primary body travelling at hypersonic speeds.An analytical methodology based on the blast wave analogy is developed and used to predict the secondary force coefficients for simple geometries in both two and three dimensions. When the secondary body is entirely inside the primary shocked region, the nature of the lateral force coefficient is found to depend strongly on the relative size of the two bodies. For two spheres, the methodology predicts that the secondary body will experience an exclusively attractive lateral force if the secondary diameter is larger than one-sixth of the primary diameter. The analytical results are compared with those from numerical simulations and reasonable agreement is observed if an appropriate normalization for the relative lateral displacement of the two bodies is used.Results from a series of experiments in the T5 hypervelocity shock tunnel are also presented and compared with perfect-gas numerical simulations, with good agreement. A new force-measurement technique for short-duration hypersonic facilities, enabling the experimental simulation of the proximal bodies problem, is described. This technique provides two independent means of measurement, and the agreement observed between the two gives a further degree of confidence in the results obtained.

1P-201 Lateral force measurement of cytoskeletal deformation by AFM(The 46th Annual Meeting of the Biophysical Society of Japan)

2008 ◽  
Vol 48 (supplement) ◽  
pp. S52
Author(s):  
Tomoro Hakari ◽  
Hiroshi Sekiguchi ◽  
Ichiro Harada ◽  
Toshiya Osada ◽  
Atsushi Ikai
Keyword(s):  
Annual Meeting ◽  
Force Measurement ◽  
Lateral Force ◽  
Biophysical Society

scholarly journals Turbulent Coagulation of Aerosol Particles: New Insights From Direct Numerical Simulations and Holographic Imaging Experiments

2003 ◽  
Author(s):  
Lance R. Collins ◽  
Hui Meng ◽  
Aruj Ahluwalia ◽  
Lujie Cao ◽  
Gang Pan
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Search Algorithm ◽  
Concentration Field ◽  
Direct Numerical Simulations ◽  
Three Dimensions ◽  
Collision Kernel ◽  
Coagulation Rate ◽  
Subsequent Work ◽  
Turbulent Fluctuations

Particle collisions driven by turbulent fluctuations play a key role in such diverse problems as cloud formation, aerosol powder manufacturing and inhalation drug therapy to name a few. In all of these examples (and many others) turbulent fluctuations increase the rate of collisions relative to the background collision rate driven by Brownian motion. Furthermore, turbulence can spontaneously generate very large fluctuations in the particle concentration field. This “clustering” is caused by the inertial mismatch between the heavy particles and the lighter surrounding gas; vortices in the flow “centrifuge” the heavier particles out of vortex cores and into the straining regions that lie in between the vortices. Because collision is a binary process, concentration fluctuations further enhance the turbulent coagulation rate by as much as two orders of magnitude. An effect of this size must be accounted for in a rational model of turbulent coagulation. Sundaram & Collins (J. Fluid Mech. 1997) showed that the radial distribution function (RDF) of the particle population, evaluated at contact, precisely corrects the collision kernel for clustering. Subsequent work has explored the dependence of the RDF on the system parameters (e.g., particle size, concentration, response time and Reynolds number) using direct numerical simulations. These results have improved our understanding and ability to predict the effect of the first three parameters; however, owing to the limited range of Reynolds number that can be reached in a numerical simulation, questions remain over the scaling of the RDF with Reynolds number. This is a critical issue for high-Reynolds-number applications such as cloud physics, where values of the Reynolds number can be 1–2 orders of magnitude greater than can be simulated. We will present our highest Reynolds number simulations to date and show our attempts to resolve this issue. Recently, the ability to measure three-dimensional particle positions using holography has been realized (e.g., Meng & Pu, J. Opt. Soc. Am. 2003). With holography, the optical image that is produced contains fringes that, upon inverting the laser, reproduce the original image in three dimensions. The hologram can then be scanned using a digital camera to obtain the particle positions. An important consideration with this study is the need to differentiate individual particles. We developed a search algorithm that locates particle centers, even in the presence of optical aberations and speckle noise. The algorithm has been used to obtain the first experimental RDF measurements to date. Thus far we see good agreement between the experimentally obtained RDF and the simulations. Besides validating the simulations, experiments can span a much broader range of Reynolds numbers, providing critical data that may help resolve the open questions associated with this parameter.

scholarly journals Three-dimensional magnetic reconnection and its application to solar flares

2017 ◽  
Vol 83 (1) ◽  
Author(s):  
Miho Janvier
Keyword(s):  
Kinetic Energy ◽  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Solar Flares ◽  
Magnetic Energy ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Current Layer ◽  
Solar Observations ◽  
The Universe

Solar flares are powerful radiations occurring in the Sun’s atmosphere. They are powered by magnetic reconnection, a phenomenon that can convert magnetic energy into other forms of energy such as heat and kinetic energy, and which is believed to be ubiquitous in the universe. With the ever increasing spatial and temporal resolutions of solar observations, as well as numerical simulations benefiting from increasing computer power, we can now probe into the nature and the characteristics of magnetic reconnection in three dimensions to better understand the phenomenon’s consequences during eruptive flares in our star’s atmosphere. We review in the following the efforts made on different fronts to approach the problem of magnetic reconnection. In particular, we will see how understanding the magnetic topology in three dimensions helps in locating the most probable regions for reconnection to occur, how the current layer evolves in three dimensions and how reconnection leads to the formation of flux ropes, plasmoids and flaring loops.

Experimental Device of Drilling String Dynamics in Horizontal Well and its Application

2013 ◽  
Vol 683 ◽  
pp. 690-693 ◽  
Author(s):  
Dong Dong Shao ◽  
Zhi Chuan Guan ◽  
Xin Wen
Keyword(s):  
Horizontal Well ◽  
Lateral Displacement ◽  
Lateral Force ◽  
Experimental Results ◽  
Experimental Device ◽  
Simulated Experiment ◽  
Bottom Hole ◽  
Drilling String ◽  
Rotary Speed ◽  
Set Up

According to the principle of similitude, a simulation experimental device for investigating drilling string dynamics in horizontal well was designed and set up. The rotary speed, WOB, drilling string lateral displacement, bottom hole WOB fluctuations and lateral force of the bit, etc. can be measured under different WOB and rotary speed by the experimental device; Some debugging experiments have been done by means of the device under different weights on bit and rotary speeds. The simulated experiment has many advantages comparing to the actual experiment, such as less operators, less times and moneys. It is easy to operate, the drilling string movement can be visually observed and all of the experimental results can be used to the actual drilling.

scholarly journals Evaluation of Failure Probability in Series System of Three-Axle Trucks under Strong Crosswind

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yahui Hu ◽  
Yingshi Guo ◽  
Rui Fu ◽  
Qingjin Xu
Keyword(s):  
Failure Probability ◽  
Lateral Displacement ◽  
Center Of Mass ◽  
Time History ◽  
General Information ◽  
Time Varying ◽  
Series System ◽  
Road Transportation ◽  
Force Coefficient ◽  
Average Wind Speed

The probability of wind-induced failure accidents in three-axle trucks under pulsating strong crosswinds and the corresponding critical safe speed are investigated in this study. Reliability theory and random fuzzy methods are utilized to establish the membership function of the failure probability in the series system (FPSS) composed of rollover, side-slip, and rotation failure accidents. The Kaman spectrum is used to realistically simulate the fluctuating wind time history curves of different average speeds. Four factors affecting the six-component force coefficient of the three-axle truck and the crosswind load are considered: fluctuating average wind speed, wind direction (angle), truck driving speed, and road adhesion coefficient. A three-axle truck nonlinear model is established accordingly. The model is used to obtain the dynamic response of the three-axle truck under strong crosswind conditions as per the time-varying curves of the vertical load of the truck, the time-varying curves of the lateral displacement of the center of mass, and the time-varying curves of the heading angle. An advanced Monte Carlo simulation algorithm based on importance sampling is used to determine the probability of a three-axle truck with FPSS under strong crosswinds; the given acceptable probability of failure (accident) is used to obtain the critical safety speed. The sensitivity analysis of random variables reveals that the possibility of three truck failures of the three-axle truck in strong crosswinds is, from largest to smallest, rollover, side-slip, and rotation. This research may provide useful guidance for exploring the probability of wind-induced accidents and the critical safety speeds of vehicles, as well as useful general information for road transportation management departments.

scholarly journals A Conceptual Design for Deflection Device in VTDP System

2020 ◽  
Author(s):  
Yongwei Gao ◽  
Jianming Zhang ◽  
Long Wang ◽  
Bingzhen Chen ◽  
Binbin Wei
Keyword(s):  
Numerical Simulation ◽  
Power Consumption ◽  
Numerical Simulations ◽  
Conceptual Design ◽  
Lateral Force ◽  
Simulation Approach ◽  
Lower Power ◽  
Ducted Propeller ◽  
Vectored Thrust ◽  
Hovering Control

Abstract The effectiveness of the Vectored Thrust Ducted Propeller (VTDP) system is not high currently, especially the lateral force is not large enough. Thus, a conceptual design for a deflection device of a VTDP system was proposed to achieve effective hovering control. The magnitude of the lateral force that was applied to maintain balance while hovering was examined. A comparison between the experimental and numerical results for the 16H-1 was made to verify the numerical simulation approach. The deflection devices of the X-49 and the proposed design were analyzed using numerical simulations. The results indicated that a larger lateral force and lower power consumption were presented in the proposed design. The results of this article provide a new idea for the design of the VTDP system.

Effects of Track Elasticity on Wheel-Rail Dynamic Performance of Heavy Haul Railway

2015 ◽  
Vol 744-746 ◽  
pp. 1249-1252 ◽  
Author(s):  
Yong Zeng
Keyword(s):  
Lateral Displacement ◽  
Dynamic Performance ◽  
Lateral Force ◽  
Vertical Force ◽  
Heavy Vehicles ◽  
Derailment Coefficient ◽  
Heavy Haul ◽  
Dynamics Models ◽  
Heavy Haul Railway ◽  
The Impact

Two vehicle-track dynamics models on heavy haul railway are established in two conditions of rigid track and elastic track. And the impact of track elasticity on the wheel-rail dynamics performance was analyzed using models. The results show that the critical speed of heavy vehicles and wheel-rail dynamic indexes, such as wheel-rail lateral force and wheel-rail vertical force decreased on elastic track compared with rigid track. However, other dynamic indexes, including derailment coefficient and lateral displacement of wheelsets increased on elastic track. And the wheel-rail wear indexes are some differences on two tracks.

Surgical Correction of Congenital Bilateral Patellar Luxation in a Pup - A Case Report

2018 ◽  
Vol 13 (03) ◽  
Author(s):  
K. Mohd. Arif Basha ◽  
K.M. Srinivasa Murthy ◽  
L. Ranganath
Keyword(s):  
Lateral Displacement ◽  
Longitudinal Axis ◽  
Lateral Force ◽  
Genu Valgum ◽  
Coxa Vara ◽  
Trochlear Groove ◽  
Developmental Abnormalities ◽  
Skeletal Abnormalities ◽  
Stifle Joint ◽  
Traumatic Origin

Luxation of patella may be congenital or traumatic origin, and can affect any breed. The congenital form is related to developmental abnormalities of the limb that create malalignment of quadriceps group of muscles. With underlying abnormalities of hip and stifle joint congenital lateral patellar luxation have skeletal abnormalities like retroversion of femoral head and neck, coxa vara (altered angle of inclination), genu valgum and shallow trochlear groove with poorly developed trochlear ridges (Denny and Butterworth, 2006). Luxation of patella is a common cause of lameness in dog which can be in medial or lateral displacement. The incidence of medial patellar luxation is 5 times more than lateral luxation and is seen more in large breeds of dogs. Lateral patellar luxation may predispose the dogs to knock knee (genu valgum) and cow hock (hock valgus) condition (Robins, 1990). The cause of lateral patellar luxation is unknown but is thought to be related to anteversion or coxa valga of the coxofemoral joint, which shifts the line of force produced by the pull of quadriceps lateral to the longitudinal axis of the trochlear groove. This abnormally directed lateral force pulls the patella from the trochlear sulcus causing skeletal abnormalities (Fossum, 2002).

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