NUMERICAL ANALYSIS OF LARGE SCALE STRATIFIED FLOWS AROUND AN HORIZONTAL STRIP

2016 ◽  
Author(s):  
M. Riahi Khalloufi ◽  
H. Houcine ◽  
Ph. Fraunié ◽  
Y. D. Chashechkin ◽  
A. Gharbi
Keyword(s):  
Numerical Analysis ◽  
Large Scale ◽  
Stratified Flows ◽  
Horizontal Strip

scholarly journals Analysis of Pore Water Pressure and Piping of Hydraulic Well

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Jinman Kim ◽  
Heuisoo Han ◽  
Yoonhwa Jin
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydraulic Gradient ◽  
Water Levels ◽  
Seepage Velocity ◽  
Seepage Analysis

This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.

scholarly journals High-resolution large-eddy simulations of sub-kilometer-scale turbulence in the upper troposphere lower stratosphere

2013 ◽  
Vol 13 (12) ◽  
pp. 31891-31932 ◽  
Author(s):  
R. Paoli ◽  
O. Thouron ◽  
J. Escobar ◽  
J. Picot ◽  
D. Cariolle
Keyword(s):  
Large Scale ◽  
Lower Stratosphere ◽  
Atmospheric Model ◽  
Large Eddy Simulations ◽  
Stratified Flows ◽  
Flow Topology ◽  
Upper Troposphere ◽  
Large Eddy ◽  
Scale Turbulence ◽  
The Impact

Abstract. Large-eddy simulations of sub-kilometer-scale turbulence in the upper troposphere lower stratosphere (UTLS) are carried out and analyzed using the mesoscale atmospheric model Méso-NH. Different levels of turbulence are generated using a large-scale stochastic forcing technique that was especially devised to treat atmospheric stratified flows. The study focuses on the analysis of turbulence statistics, including mean quantities and energy spectra, as well as on a detailed description of flow topology. The impact of resolution is also discussed by decreasing the grid spacing to 2 m and increasing the number of grid points to 8×109. Because of atmospheric stratification, turbulence is substantially anisotropic, and large elongated structures form in the horizontal directions, in accordance with theoretical analysis and spectral direct numerical simulations of stably stratified flows. It is also found that the inertial range of horizontal kinetic energy spectrum, generally observed at scales larger than a few kilometers, is prolonged into the sub-kilometric range, down to the Ozmidov scales that obey isotropic Kolmorogov turbulence. The results are in line with observational analysis based on in situ measurements from existing campaigns.

Numerical analysis of working fluids for large scale centrifugal compressor driven cascade heat pumps upgrading waste heat

2020 ◽  
Vol 269 ◽  
pp. 115056 ◽  
Author(s):  
Antti Uusitalo ◽  
Teemu Turunen-Saaresti ◽  
Juha Honkatukia ◽  
Jonna Tiainen ◽  
Ahti Jaatinen-Värri
Keyword(s):  
Numerical Analysis ◽  
Centrifugal Compressor ◽  
Large Scale ◽  
Waste Heat ◽  
Heat Pumps ◽  
Working Fluids

On the dynamics of turbulence near a free surface

2017 ◽  
Vol 821 ◽  
pp. 248-265 ◽  
Author(s):  
Oscar Flores ◽  
James J. Riley ◽  
Alexander R. Horner-Devine
Keyword(s):  
Free Surface ◽  
Vertical Velocity ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Field Measurements ◽  
Inertial Range ◽  
Stratified Flows ◽  
Range Type ◽  
Spectral Behaviour ◽  
Vertical Shearing

We report on direct numerical simulations to examine the spectral behaviour of turbulence close to and at a flat, stress-free surface. We find, consistent with field measurements near such a free surface, that an inertial-range type of behaviour is obtained for the horizontal components of the velocity at and near the stress-free surface, at horizontal wavelengths for which the vertical velocity is much smaller than the horizontal components. At approximately an integral length scale from the stress-free surface, the flow has adjusted back to more classical isotropic turbulence. The behaviour of the turbulence near the stress-free surface is similar to that observed recently for strongly stratified flows, and we argue that the causes of that behaviour are the same in both flows: the suppression of the large-scale vertical velocity and the allowance of strong vertical shearing of the horizontal velocity leading to a downscale transfer of energy and to the development of the$-5/3$spectra for the horizontal velocities.

Preliminary Study on Long-Term Flooding After the Tsunami

2017 ◽  
Vol 12 (4) ◽  
pp. 741-747
Author(s):  
Toshitaka Baba ◽  
Junichi Taniguchi ◽  
Noriko Kusunoki ◽  
Manabu Miyoshi ◽  
Hiroshi Aki ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Large Scale ◽  
Water Exchange ◽  
Ground Surface ◽  
Flow Modeling ◽  
Tsunami Waveforms ◽  
Long Time ◽  
Preliminary Study ◽  
Nankai Earthquake

After the Nankai earthquake in 1946, the resultant flooding lasted for a long time, because seawater remained on land after the tsunami in Kochi city. Large-scale flooding occurred in Ishinomaki city immediately after the Great East Japan Earthquake in 2011. Long-term flooding may hamper disaster responses such as rescue and recovery activities. This paper studied the risks of long-term flooding after the Nankai earthquake in Tokushima city based on a paleographical survey and numerical analysis. The paleographical survey identified statements such as “seawater sometimes flowed onto the land at the full tide,” suggesting occurrences of long-term flooding after previous Nankai earthquakes. The numerical analysis separately calculated values inside and outside the levee. The tsunami waveforms outside the analysis area obtained by tsunami numerical simulation was used as the boundary condition of the inland flow modeling, that is water was introduced inside the levee when the tsunami water level exceeded the upper end of the levee. The two layers of ground surface and the drain were defined to calculate the flow, including water exchange between the two layers, and the water was drained forcefully outside the levee using a drainage pump. The possibility of long-term flooding in the analysis area is suggested when a large-scale earthquake occurs in the Nankai trough.

On the statistics of the linked stress release model

2001 ◽  
Vol 38 (A) ◽  
pp. 176-187 ◽  
Author(s):  
Mark Bebbington ◽  
David S. Harte
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Numerical Analysis ◽  
Large Scale ◽  
Point Processes ◽  
Information Criterion ◽  
Stress Release ◽  
Stress Release Model ◽  
Using Data ◽  
Release Model

The paper reviews the formulation of the linked stress release model for large scale seismicity together with aspects of its application. Using data from Taiwan for illustrative purposes, models can be selected and verified using tools that include Akaike's information criterion (AIC), numerical analysis, residual point processes and Monte Carlo simulation.

Numerical analysis of gas production from large-scale methane hydrate sediments with fractures

Energy ◽  
2021 ◽  
pp. 121485
Author(s):  
Yongchang Feng ◽  
Lin Chen ◽  
Yuki Kanda ◽  
Anna Suzuki ◽  
Atsuki Komiya ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Methane Hydrate ◽  
Large Scale ◽  
Gas Production

Calculation on Friction Pressure Gradient of Gas-Liquid Stratified Flows in Condensate Natural Gas Pipeline

2011 ◽  
Vol 356-360 ◽  
pp. 875-880
Author(s):  
Rong Ge Xiao ◽  
Bing Qian Wei ◽  
Gang Chen
Keyword(s):  
Natural Gas ◽  
Pressure Gradient ◽  
Large Scale ◽  
Flow Characteristics ◽  
Gas Pipeline ◽  
Stratified Flows ◽  
Momentum Balance ◽  
Two Phase ◽  
Natural Gas Pipeline ◽  
Liquid Flows

Flow characteristics of horizontal two-phase gas-liquid stratified flows in condensate natural gas pipeline are studied through both air-water and air- natural gas condensate experiments on the large-scale multiphase experimental loop. Based on measurement and observation of flow pattern, “apparent rough surface” (ARS) model is selected to calculate frictional pressure gradient with gas-liquid momentum balance equations. The predictions of the models are compared with the data measured in the experiment. Some results of pressure gradient are obtained, so ARS interfacial shape is recommended in horizontal two-phase gas-liquid flows with low liquid loading.

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