scholarly journals Numerical simulations show potential for strong nonisothermal effects during fluid leakage from a geologic disposal reservoir for CO2

2013 ◽  
pp. 81-89 ◽  
Author(s):  
Karsten Pruess
Keyword(s):  
Numerical Simulations ◽  
Fluid Leakage ◽  
Geologic Disposal

Using Leakage to Stabilize a Hydraulic Circuit for Pump Controlled Actuators

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Longke Wang ◽  
Wayne J. Book
Keyword(s):  
Energy Efficiency ◽  
System Dynamics ◽  
Numerical Simulations ◽  
Lower Cost ◽  
System Stability ◽  
Mode Switching ◽  
Hydraulic Circuit ◽  
Controlled System ◽  
Fluid Leakage ◽  
Controlled Systems

Pump controlled hydraulic actuators offer higher energy efficiency than valve controlled actuators. However, there exists mode switching in pump controlled systems and instability may arise when a single rod cylinder is implemented. This paper examines the problem of system stability in a pump controlled system with single rod cylinders. It is shown that the system dynamics have a stable tendency or an instable tendency corresponding to different cylinder movements. The paper shows system instability can be avoided by controlling fluid leakage, and two applicable methods are presented: physical leakage compensation and virtual leakage compensation, which can be applied depending on applications. Experiments and numerical simulations are presented. Results show that the proposed solutions can maintain circuit stability: physical leakage compensation can be a general approach while virtual leakage compensation offers higher energy efficiency and lower cost, but its applications are limited by some factors.

Spinal Fluid Leakage After Skull Base Surgical Procedures

1984 ◽  
Vol 17 (3) ◽  
pp. 601-612 ◽  
Author(s):  
Donald L. Myers ◽  
Robert Thayer Sataloff
Keyword(s):  
Skull Base ◽  
Surgical Procedures ◽  
Spinal Fluid ◽  
Fluid Leakage

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

Modeling and Evaluation of Magnetorheological Dampers with Fluid Leakage for Cable Vibration Control

2021 ◽  
Vol 26 (2) ◽  
pp. 04020119
Author(s):  
Peng Zhou ◽  
Min Liu ◽  
Weiming Kong ◽  
Yingmei Xu ◽  
Hui Li
Keyword(s):  
Vibration Control ◽  
Magnetorheological Dampers ◽  
Cable Vibration ◽  
Fluid Leakage
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