scholarly journals An extension of Fuhrboter's studies for wave height: a theoretical study

1970 ◽  
Vol 34 (2) ◽  
pp. 115-122
Author(s):  
Azizur Rahman ◽  
MST Kamrunnaher ◽  
Ashabul Hoque
Keyword(s):  
Key Words ◽  
Wave Height ◽  
Theoretical Study ◽  
Air Entrainment ◽  
Air Bubbles ◽  
Air Bubble ◽  
Bubble Entrainment ◽  
Air Bubble Entrainment ◽  
Spilling Breakers ◽  
Academy Of Sciences

This theoretical study extends Fuhrboter's work and includes the effects of air bubble entrainment. Result shows that there is a correlation between the sudden reductions of wave height and entrained of air bubbles into the water. Moreover, the study reveals that air entrainment occurs very short way in plunging breakers comparatively to spilling breakers. Key words: Fuhrboter's studies; Wave height; Theoretical study DOI: 10.3329/jbas.v34i2.6855Journal of Bangladesh Academy of Sciences, Vol. 34, No. 2, 115-122, 2010

scholarly journals Similitude of Air Entrainment at Vertical Circular Plunging Jets

2002 ◽  
Author(s):  
Hubert Chanson ◽  
Shin-Ichi Aoki ◽  
Ashabul Hoque
Keyword(s):  
Scale Effects ◽  
Air Entrainment ◽  
Air Bubble ◽  
Bubble Dispersion ◽  
Jet Impact ◽  
Scale Models ◽  
Bubble Entrainment ◽  
Plunging Jets ◽  
Air Bubble Entrainment ◽  
Inflow Conditions

Air bubble entrainment at plunging jet takes place when the jet impact velocity exceeds a critical velocity function of the inflow conditions. This study investigates scale effects affecting air entrainment and bubble dispersion at vertical circular plunging jets. Three scale models were used and detailed air-water measurements were performed systematically for identical Froude numbers. The results highlight significant scale effects when We1 < 1E+3 or V1/ur < 10. Bubble chord times were also measured and presented in terms of pseudo-bubble chord length which was found to overestimate real bubble chords by 10 to 30%. The data show pseudo-bubble chord sizes ranging from less than 0.5 mm to more than 10 mm. The average pseudo-chord sizes were between 5 and 7 mm.

scholarly journals MODIFICATION EQUATIONS OF AIR BUBBLES DISTRIBUTIONS AT SELF-AIR ENTRAINMENT CONDITION

2020 ◽  
Vol 82 (2) ◽  
Author(s):  
Yeri Sutopo ◽  
Budi S. Wignyosukarto ◽  
Bambang Yulistyanto ◽  
Istiarto Istiarto ◽  
Nor Hayati Abdul Hamid
Keyword(s):  
Concentration Distribution ◽  
Vertical Direction ◽  
Air Entrainment ◽  
Experimental Results ◽  
Air Bubbles ◽  
Air Concentration ◽  
Air Bubble ◽  
Discharge Water ◽  
Flow Surface ◽  
Imagej Software

The Chanson’s equation for distribution of air bubbles in vertical direction in the developing zone at self-air entrainment condition is used when the air bubbles concentration at the flow surface is 90%. Otherwise, if this condition is not satisfying, then the equations of Straub and Anderson can be used. The results of these two equations are not similar with experimental results. Therefore, these two equations need to be modified accordingly. These modification equations can also be used to predict the air bubbles distributions in vertical direction. Hence, the main objective of this study is to modify these equations for vertical air concentration distribution in the developing zone and validate them with experimental results. The steep channel in the form of flume with 10 m long, 0.2 m wide and 0.4 m high with slopes varies between 20° and 25° were used in this experimental work. The discharge water was 9 l/s, 12 l/s and 21 l/s with Froude numbers between 6.9 to 8.0. The Thomson weir (V Notch) was used to calibrate the discharge flow of water. A set of video cameras was used to record the motion pictures of the air bubbles. The air bubble was analyzed using Ulead Video Studio 11 software program equipped with Imagej software. The results of this study indicates that the modifications of equations of Straub and Anderson were the equation air concentration distribution (C) in the underlying zone value was 0.647 m at 20° slope of channel bed, the equation air concentration distribution (C) in the underlying zone the value was 0.542 m at 25° slope and the equation in the mixing zone remained the same. The original Chanson equation was modified mainly in terms of the hyperbolic tangent (tanh) equation which originally had a power of 2 while the modification was 0.8; and the Ce was 0.9 sin α, whereas at the modified Chanson’s equation, Ce was converted into Ce= 0.6 sin α.

scholarly journals F113 Improvement of Hydrofoil Performance on Air Bubble Entrainment for Drag Reduction of Ships

2013 ◽  
Vol 2013.18 (0) ◽  
pp. 187-188
Author(s):  
Ichiro KUMAGAI ◽  
Haruki SAKAMAKI ◽  
Yuji TASAKA ◽  
Yoshihiko OISHI ◽  
Yuichi MURAI
Keyword(s):  
Drag Reduction ◽  
Air Bubble ◽  
Bubble Entrainment ◽  
Air Bubble Entrainment

Irregular Bubble Entrainment Following Drop Impact on a Free Surface

2003 ◽  
Author(s):  
Yukio Tomita ◽  
Toshiyasu Kasai ◽  
Shinya Miura
Keyword(s):  
Free Surface ◽  
Impact Velocity ◽  
Water Surface ◽  
Drop Impact ◽  
Drop Diameter ◽  
Air Bubbles ◽  
Air Bubble ◽  
Bubble Entrainment ◽  
Irregular Case ◽  
The Impact

An air bubble is entrained by the impact of a drop on a water surface. Consequently sound is emitted. There are two categories of the bubble entrainment depending on the drop diameter dD and impact velocity Vimp. One is the regular entrainment where air bubbles are always pinched off, another is the irregular case where bubbles are trapped irregularly. In this paper we explore the mechanism of the irregular bubble entrainment and induced bubble sound.

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