Experimental Investigations of Hydraulic Surges Passing Over a Rectangular Canal

2020 ◽  
Vol 14 (05) ◽  
pp. 2040004
Author(s):  
Nuri Elsheikh ◽  
Amir H. Azimi ◽  
Ioan Nistor ◽  
Abdolmajid Mohammadian
Keyword(s):  
Steady State ◽  
Wave Height ◽  
Time History ◽  
Wave Model ◽  
Dam Break ◽  
Experimental Investigations ◽  
Quasi Steady State ◽  
Physical Experiments ◽  
Before And After ◽  
Surge Height

The purpose of this experimental study was to investigate the effects of a rectangular canal on the hydrodynamics of turbulent surges before and after the canal by implementing a series of physical experiments. A dam-break wave model was used to simulate the tsunami-like turbulent waves passing over a smooth and horizontal surface, in the presence and absence of a canal. Three canal depths of [Formula: see text], 0.10 and 0.15[Formula: see text]m were used to model shallow, moderate and deep conditions and three canal widths of [Formula: see text], 1.60 and 3.0[Formula: see text]m were selected to model narrow to wide canals. The front velocity of the dam-break induced surges were controlled by rapidly releasing upstream impounded set volumes of water with depths of [Formula: see text], 0.30 and 0.40[Formula: see text]m. The dam-break wave propagation over a horizontal, dry and smooth bed revealed four regimes describing the variations of surge height with time. The arrival time to reach the maximum surge height and the quasi steady-state regime was correlated with each impoundment depth and an empirical formulation was proposed to estimate the onset of the quasi steady-state flow. The maximum surge heights measured before and after the mitigation canal location were compared with those recorded in the corresponding tests without the presence of the canal. It was found that the peak surge height upstream of the canal could increase up to 40% compared to the test without the presence of the canal in relatively small impoundment depth and in presence of a narrow canal due to momentum dissipation. The wave height downstream of the canal increased between 10% and 50% of the wave height without the presence of the canal and the minimum change in the wave height occurred for the canal width to depth ratio of 20. The time-history of surge velocity after the mitigation canal indicated a significant decay of between 40% and 60% in the presence of a canal due to the bed friction changes and momentum dissipation.

Investigations of Reduction Effect of Vertical Wall on Dam-Break-Simulated Tsunami Surge Exerted on Wharf Piles

2018 ◽  
Vol 12 (02) ◽  
pp. 1840006 ◽  
Author(s):  
Cheng Chen ◽  
Bruce W. Melville ◽  
N. A. K. Nandasena
Keyword(s):  
High Speed ◽  
Preliminary Investigation ◽  
Vertical Wall ◽  
Pressure Sensors ◽  
Time History ◽  
Dam Break ◽  
Reservoir System ◽  
Reduction Effect ◽  
The Impact ◽  
Surge Height

For a preliminary investigation of the impact of a tsunami surge on wharf piles, a tsunami flume was built in a laboratory, and a dam break flow was generated by a gate-reservoir system to simulate a tsunami surge. In addition, a vertical wall was installed in front of the wharf model so that its effect in reducing tsunami load could be studied. Five different tsunami surge strengths were generated by this gate-reservoir system. Wave transducers were used in the test flume to capture surge heights and velocities, and hence the surge front profiles, for different surge strengths. High-speed video cameras (210 frames per second) were used to record the flow motion of the tsunami surge, and pressure sensors (1000[Formula: see text]Hz in frequency) were used to capture the time histories of the tsunami pressure on the wharf piles. Four stages of tsunami surge motions were observed by this high-speed camera. Accordingly, the pressure time history can be divided into three phases. In our experimental range, pressures were influenced by surge height and wall height, but not by the wall position. Based on the dimensionless experimental data (pile heights, surge heights, vertical wall heights, and surge pressures), equations for estimating tsunami loads on wharf pile are proposed, expressing surge front (peak impact) pressure and quasi-steady pressure as functions of surge height, wall height, and pile height.

Experimental Investigations of the Strong Off-Resonant Comb (SORC) Pulse Sequence in 14N NQR

1992 ◽  
Vol 47 (1-2) ◽  
pp. 415-420 ◽  
Author(s):  
S. S. Kim ◽  
J. R. P. Jayakody ◽  
R. A. Marino
Keyword(s):  
Steady State ◽  
Pulse Sequence ◽  
Frequency Offset ◽  
Experimental Investigations ◽  
Quasi Steady State ◽  
Signal Averaging ◽  
Pulse Parameters ◽  
Free Induction ◽  
Signal Response

AbstractThe behavior of induction signals during steady-state pulse irradiations in 14N NQR was investigated experimentally. It has long been known that the signal response to a long sequence of η pulses will dramatically increase for pulse spacings less than T2. This increase is exponential, and can result in signals comparable to optimally prepared Free Induction Decays. Because these "SORC" signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these quasi steady-state signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method.

scholarly journals Experiments on initial stages of development of dam-break waves

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Lélis Espartel ◽  
Rafael Manica
Keyword(s):  
Wave Height ◽  
Water Depth ◽  
Dam Break ◽  
Effective Height ◽  
Maximum Wave Height ◽  
Effective Velocity ◽  
Physical Experiments ◽  
Dimensional Parameters ◽  
Wave Break ◽  
Water Depths

ABSTRACT The initial stages of instantaneous dam-break waves are here evaluated spatially and temporally through 36 physical experiments. Different conditions were tested for downstream (J) and upstream (M) water depths and their ratios (r) to approach realistic conditions for prototype dams. Two non-dimensional parameters are proposed – effective height (HEF) and effective velocity (VEF) – to evaluate water depths and velocity peaks along the dam-break wave evolution. The maximum wave height is estimated as a function of r, whereas the HEF is inversely related to r. The maximum VEF peak is registered for r between 0.1 and 0.2, considered a critical description for real dams. The presence of downstream water depth also modifies the dam-break wave frontal shape and types of wave break features. Previously published classifications of the moving wave based on those features are now expanded with a first tested r = 0.8 in which no jet was identified (undulated movement).

Network reconstruction based on steady-state data

2008 ◽  
Vol 45 ◽  
pp. 161-176 ◽  
Author(s):  
Eduardo D. Sontag
Keyword(s):  
Steady State ◽  
Reverse Engineering ◽  
Theoretical Method ◽  
Network Reconstruction ◽  
Quasi Steady State ◽  
State Data

This paper discusses a theoretical method for the “reverse engineering” of networks based solely on steady-state (and quasi-steady-state) data.

Quasi-steady-state performance of a heat pipe subjected to transient acceleration loadings

10.2514/3.895 ◽  
1997 ◽  
Vol 11 ◽  
pp. 306-309 ◽  
Author(s):  
Edwin H. Olmstead ◽  
Edward S. Taylor ◽  
Meng Wang ◽  
Parviz Moin ◽  
Scott K. Thomas ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Quasi Steady State ◽  
Steady State Performance

A Graphical Method for Storage Coefficient Determination from Quasi-Steady State Flow Data

1996 ◽  
Vol 27 (4) ◽  
pp. 247-254 ◽  
Author(s):  
Zekâi Şen
Keyword(s):  
Steady State ◽  
Graphical Method ◽  
Pumping Test ◽  
Quasi Steady State ◽  
Flow Data ◽  
Steady State Flow ◽  
Storage Coefficient ◽  
State Flow ◽  
Aquifer Test

A simple, approximate but practical graphical method is proposed for estimating the storage coefficient independently from the transmissivity value, provided that quasi-steady state flow data are available from a pumping test. In the past, quasi-steady state flow distance-drawdown data have been used for the determination of transmissivity only. The method is applicable to confined and leaky aquifers. The application of the method has been performed for various aquifer test data available in the groundwater literature. The results are within the practical limits of approximation compared with the unsteady state flow solutions.

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