Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

2021 ◽  
pp. 147509022110313
Author(s):  
T J Jemi Jeya ◽  
V Sriram ◽  
V Sundar
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Scattering Parameter ◽  
Oblique Waves ◽  
Test Conditions ◽  
Relative Water ◽  
Identical Test ◽  
Run Up ◽  
Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

Hydrodynamic characteristics of a submerged trapezoidal artificial reef unit

2019 ◽  
Vol 233 (4) ◽  
pp. 1226-1239
Author(s):  
Lokesha ◽  
SA Sannasiraj ◽  
Vallam Sundar
Keyword(s):  
Artificial Reef ◽  
Hydrodynamic Performance ◽  
Artificial Reefs ◽  
Hydrodynamic Characteristics ◽  
Leeward Side ◽  
Random Waves ◽  
Relative Water ◽  
Marine Flora ◽  
Water Depths ◽  
Crest Height

Submerged structures serve as wave attenuators and are widely adopted for protecting the coast against erosion or to reduce forces on structures situated on its leeward side. Conventional submerged breakwaters are composed of rubble stones, and the sources for quarrying such stones have depleted drastically over a period of time. The artificial reefs are a replacement for submerged breakwaters formed by natural rocks due to its minimum impact on the marine environment, flexibility in molding to any desired shape and size. It is also believed to serve as a habitable environment to marine flora and fauna. In this study, a comprehensive experimental investigation is carried out in order to examine the effect of perforations on a submerged artificial reef exposed to regular and random waves. The tests with models of crest width ( B) of 0.2 m and crest height ( h) of 0.4 m are conducted for three different degrees of submergence ( d/ h) of 1.5, 1.38 and 1.25 in three different water depths, d. The article emphasizes the influence of relative water depth, relative crest width and the nature of the surface of the structure (impermeable or permeable) on its hydrodynamic performance characteristics.

Measurement of Noise inside the Compartment and Vibration on both Sides of Elastomeric Powertrain Mounts of Passenger Car

2013 ◽  
Vol 471 ◽  
pp. 59-63
Author(s):  
Mohd Noor Arib Rejab ◽  
Roslan Abd Rahman ◽  
Raja Ishak Raja Hamzah ◽  
Jawaid Iqbal Inayat Hussain ◽  
Nazirah Ahmad ◽  
...  
Keyword(s):  
Fast Response ◽  
Sound Level ◽  
Measurement Noise ◽  
The Other ◽  
Vibration Level ◽  
Test Conditions ◽  
Exhaust Noise ◽  
Run Up ◽  
Level Meter ◽  
High Level

This paper presents an evaluation on elastomeric mount used to isolate vibration from powertrain to chassis or structure vehicle. The assessments started with measurement of noise inside compartment, and exhaust noise. This is followed by the measurement of vibration on both sides of elastomeric mounts. The noise in the compartment and exhaust noise is measured according to BS 6086: 1981 and BS ISO 5130: 2007. The noise in the compartment and vibration is tested in three conditions. Firstly, engine is run-up with load (driving at second gear); secondly, without load; and thirdly, without load but hanging. A microphone is fixed at the ear of the mannequin. The fast response and A weighting sound level meter were used for measurement noise in the compartment and exhaust noise. The vibration is measured in terms of acceleration on both sides of each elastomeric powertrain mounts. Two accelerometer transducers are fixed on both sides of powertrain elastomeric mounts. One side was identified as a source of vibration and the other as receiver of vibrations. The results showed that the pattern of overall vibration level on source and receiver increased from 1050 RPM (idling) to 4000 RPM on all test conditions. Vibration transmitted to chassis or receiver structure was analyzed using transmissibility concept. By evaluating test condition of engine run-up without load, informed that the front and rear mounts showed a high level transmissibility contributing to structure-borne noise.

Erosion of 310 Stainless Steel at 975°C in Combustion Gas Atmospheres

1977 ◽  
Vol 99 (2) ◽  
pp. 126-132 ◽  
Author(s):  
L. K. Ives
Keyword(s):  
Stainless Steel ◽  
Corrosion Process ◽  
Combustion Gas ◽  
Scanning Electron Microscopy Examination ◽  
Test Conditions ◽  
310 Stainless Steel ◽  
Component Test ◽  
Multiple Component ◽  
Identical Test ◽  
Microscopy Examination

Erosion tests were conducted on 310 stainless steel in combustion gas atmospheres at 975°C. SiC particles of 100 mesh (150 μm) size were employed over a velocity range of 15–70 m/s at a 90 deg (perpendicular) angle of impingement. A comparison is made with results obtained at 25°C in air using the same test equipment. Scanning electron microscopy examination of the eroded surfaces revealed important information concerning the nature of the erosion-corrosion process. A multiple component test specimen is described for application in comparing alloys under nearly identical test conditions.

scholarly journals A SIMILARITY PARAMETER FOR BREAKWATERS: THE MODIFIED IRIBARREN NUMBER

2018 ◽  
pp. 28
Author(s):  
Maria Clavero ◽  
Pedro Folgueras ◽  
Pilar Diaz-Carrasco ◽  
Miguel Ortega-Sanchez ◽  
Miguel A. Losada
Keyword(s):  
Incident Wave ◽  
Wave Length ◽  
Slope Angle ◽  
Wave Pattern ◽  
Relative Width ◽  
Scattering Parameter ◽  
Wave Regime ◽  
Similarity Parameter ◽  
Mean Water Level ◽  
Run Up

In the 14th ICCE, Battjes (1974) showed that a single similarity parameter only, embodying both the effects of slope angle and incident wave steepness, was important for many aspects of waves breaking on impermeable slopes, and suggested to call it the "Iribarren number", denoted by "Ir". Ahrens and McCartney (1975) verified the usefulness of Ir to describe run-up and stability on rough permeable slopes. Since then, many researchers applied Ir to characterize and to develop formulae for the design of breakwaters and to verify their stability. On the other hand, depending on their typology, breakwaters reflect, dissipate, transmit, and radiate incident wave energy. Partial standing wave patterns are likely to occur at all types of breakwater, thus playing an important role in defining the wave regime in front of, near (seaward and leeward), and inside the breakwater. The characteristics of the porous medium, relative grain size D/L and relative width, Aeq/L2, are relevant magnitudes in that wave pattern (Vilchez et al. 2016), being D the grain diameter, L the wave length and Aeq the porous area per unit section under the mean water level. Aeq/L2 is a scattering parameter controlling the averaged transformation of the wave inside the porous section of the structure. For a vertical porous breakwater (Type A), Aeq is simply B · h, and for a constant depth, the scattering parameter is reduced to B/L, which is the relative breakwater width.

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