Numerical study of surface thermal signatures of lee waves excited by moving underwater sphere at low Froude number

2021 ◽  
pp. 109314
Author(s):  
Cheng-An Wang ◽  
Duo Xu ◽  
Ji-Peng Gao ◽  
Jian-Yu Tan ◽  
Zhi-Quan Zhou
Keyword(s):  
Froude Number ◽  
Numerical Study ◽  
Lee Waves ◽  
Low Froude Number

Experimental and numerical study on onset of inflow in near field of buoyant jet at low Froude number

2011 ◽  
Vol 15 (1) ◽  
pp. 67-75 ◽  
Author(s):  
T. Maeda ◽  
N. Fujisawa ◽  
T. Syuto ◽  
T. Yamagata
Keyword(s):  
Froude Number ◽  
Numerical Study ◽  
Near Field ◽  
Buoyant Jet ◽  
Low Froude Number

scholarly journals The structure of low-Froude-number lee waves over an isolated obstacle

2011 ◽  
Vol 689 ◽  
pp. 3-31 ◽  
Author(s):  
Stuart B. Dalziel ◽  
Michael D. Patterson ◽  
C. P. Caulfield ◽  
Stéphane Le Brun
Keyword(s):  
Froude Number ◽  
Three Dimensional ◽  
Classical Problem ◽  
Quantitative Agreement ◽  
Horizontal Flow ◽  
Lee Waves ◽  
Theoretical Predictions ◽  
Low Froude Number ◽  
Linearized Theory ◽  
Over The Top

AbstractWe present new insight into the classical problem of a uniform flow, linearly stratified in density, past an isolated three-dimensional obstacle. We demonstrate how, for a low-Froude-number obstacle, simple linear theory with a linearized boundary condition is capable of providing excellent quantitative agreement with laboratory measurements of the perturbation to the density field. It has long been known that such a flow may be divided into two regions, an essentially horizontal flow around the base of the obstacle and a wave-generating flow over the top of the obstacle, but until now the experimental diagnostics have not been available to test quantitatively the predicted features. We show that recognition of a small slope that develops across the obstacle in the surface separating these two regions is vital to rationalize experimental measurements with theoretical predictions. Utilizing the principle of stationary phase and causality arguments to modify the relationship between wavenumbers in the lee waves, linearized theory provides a detailed match in both the wave amplitude and structure to our experimental observations. Our results demonstrate that the structure of the lee waves is extremely sensitive to departures from horizontal flow, a detail that is likely to be important for a broad range of geophysical manifestations of these waves.

Preliminary Numerical Study of a New Slender-Ship Theory of Wave Resistance

1983 ◽  
Vol 27 (03) ◽  
pp. 172-186
Author(s):  
C. Y. Chen ◽  
F. Noblesse
Keyword(s):  
Experimental Data ◽  
Froude Number ◽  
Numerical Study ◽  
Wave Resistance ◽  
Remarkable Effect ◽  
First Order ◽  
Wave Potential ◽  
Wigley Hull ◽  
Low Froude Number ◽  
Large Phase

Results of various numerical calculations of wave resistance designed to evaluate the new slender-ship approximations obtained in Noblesse [1]3 are presented. Specifically, three main wave-resistance approximations are evaluated and studied. These are the zeroth-order slender-ship approximation r(0), which is compared with the classical approximations of Hogner and Michell; the first-order slender-ship low Froude-number approximation rIF(1), which is shown to be practically equivalent: to the Guevel-Baba-MaruoKayo low-Froude-number approximation rIF; and the first-order slender-ship approximation r(1), which is evaluated for the Wigley hull and compared with existing experimental data, corrected for effects of sinkage and trim, and with numerical results obtained by using the theory of Guilloton, the low-speed theory, and Dawson's numerical method. The approximations r(1) and rIF(1) are obtained by taking the velocity potential in the Kochin free-wave amplitude function as the first-order slender-ship potential Φ(1) and its zero-Froudenumber limit Φ0(1) respectively. A major difference between the potentials Φ(1) and Φ0(1) resides in the wave potential ΦW(1) that is included in Φ(1), but is ignored in the zero-Froude-number potential Φ0(1). It is shown that the wave potential ΦW(1) may not be neglected in comparison with the potential Φ0(1) and in fact has a remarkable effect upon the wave resistance. In particular, the wave potential ΦW(1) causes a very large phase shift of the wave-resistance curve, which results in greatly improved agreement with experimental data.

Further Results on Lee Vortices in Low-Froude-Number Flow

1991 ◽  
Vol 48 (19) ◽  
pp. 2204-2211 ◽  
Author(s):  
Richard Rotunno ◽  
Piotr K. Smolarkiewicz
Keyword(s):  
Froude Number ◽  
Low Froude Number ◽  
Number Flow

The Denver Cyclone. Part I: Generation in Low Froude Number Flow

1990 ◽  
Vol 47 (23) ◽  
pp. 2725-2742 ◽  
Author(s):  
N. Andrew Crook ◽  
Terry L. Clark ◽  
Mitchell W. Moncrieff
Keyword(s):  
Froude Number ◽  
Low Froude Number ◽  
Number Flow

Discussion of “Stilling Basin Design for Low Froude Number”

1976 ◽  
Vol 102 (6) ◽  
pp. 797-799
Author(s):  
Heramb D. Sharma ◽  
Dharam V. Varshney
Keyword(s):  
Froude Number ◽  
Stilling Basin ◽  
Low Froude Number

scholarly journals Nose-Angle Bridge Piers as Alternative Countermeasures for Local Scour Reduction

2018 ◽  
Vol 13 (2) ◽  
pp. 110-120 ◽  
Author(s):  
Ibtesam Abudallah Habib ◽  
Wan Hanna Melini Wan Mohtar ◽  
Atef Elsaiad ◽  
Ahmed El-Shafie
Keyword(s):  
Froude Number ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Skew Angle ◽  
Flow Angle ◽  
Sediment Size ◽  
Low Froude Number ◽  
Skew Angles ◽  
Depth Reduction

This study investigates the performance nose-angle piers as countermeasures for local scour reduction around piers. Four nose angles were studied, i.e., 90°, 70°, 60° and 45° and tested in a laboratory. The sediment size was fixed at 0.39 mm whereas the flow angle of attack (or skew angle) was varied at four angles, i.e., skew angles, i.e., 0°, 10°, 20° and 30°. Scour reduction was clear when decreasing nose angles and reached maximum when the nose angle is 45°. Increasing the flow velocity and skew angle was subsequently increasing the scour profile, both in vertical and transversal directions. However, the efficiency of nose angle piers was only high at low Froude number less than 0.40 where higher Froude number gives minimal changes in the maximum scour depth reduction. At a higher skew angle, although showed promising maximum scour depth reduction, the increasing pier projected width resulted in the increase of transversal lengths.

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