A Detailed Study of Transom Breaking Waves

Fu, Thomas C.; Fullerton, Anne M.; Ratcliffe, Toby; Minnick, Lisa; Walker, Don; Pence, Mary L.; Anderson, Kirk

doi:10.21236/ada499067

Cited by 8 publications

(9 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent full-scale experiments of a transom stern vessel (Fu et al 2006;Terrill & Taylor 2015) and laboratory-scale experiments of a transom hull form (Drazen et al 2010) and breaking waves (Lamarre & Melville 1991) provided significant insight into wake interface characteristics and statistics as well as initial information regarding the wake air entrainment. Based on images from experiments (Fu et al 2010a), the three-dimensional flow behind the transom stern is visually similar to the supercritical flow behind chute piers in spillways due to the presence of the characteristic rooster tail (Pagliara, Kurdistani & Roshni 2011). Laboratory-scale experiments reported void fractions within 10 %-15 % and field-scale experiments at 20 %-30 %.…”

Section: Introductionmentioning

confidence: 89%

“…Based on images from experiments (Fu et al. 2010 a ), the three-dimensional flow behind the transom stern is visually similar to the supercritical flow behind chute piers in spillways due to the presence of the characteristic rooster tail (Pagliara, Kurdistani & Roshni 2011). Laboratory-scale experiments reported void fractions within 10 %–15 % and field-scale experiments at 20 %–30 %.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Wake behind a three-dimensional dry transom stern. Part 1. Flow structure and large-scale air entrainment

Hendrickson

Weymouth

et al. 2019

J. Fluid Mech.

View full text Add to dashboard Cite

We present high-resolution implicit large eddy simulation (iLES) of the turbulent air-entraining flow in the wake of three-dimensional rectangular dry transom sterns with varying speeds and half-beam-to-draft ratios $B/D$. We employ two-phase (air/water), time-dependent simulations utilizing conservative volume-of-fluid (cVOF) and boundary data immersion (BDIM) methods to obtain the flow structure and large-scale air entrainment in the wake. We confirm that the convergent-corner-wave region that forms immediately aft of the stern wake is ballistic, thus predictable only by the speed and (rectangular) geometry of the ship. We show that the flow structure in the air–water mixed region contains a shear layer with a streamwise jet and secondary vortex structures due to the presence of the quasi-steady, three-dimensional breaking waves. We apply a Lagrangian cavity identification technique to quantify the air entrainment in the wake and show that the strongest entrainment is where wave breaking occurs. We identify an inverse dependence of the maximum average void fraction and total volume entrained with $B/D$. We determine that the average surface entrainment rate initially peaks at a location that scales with draft Froude number and that the normalized average air cavity density spectrum has a consistent value providing there is active air entrainment. A small parametric study of the rectangular geometry and stern speed establishes and confirms the scaling of the interface characteristics with draft Froude number and geometry. In Part 2 (Hendrikson & Yue, J. Fluid Mech., vol. 875, 2019, pp. 884–913) we examine the incompressible highly variable density turbulence characteristics and turbulence closure modelling.

show abstract

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Wake behind a three-dimensional dry transom stern. Part 1. Flow structure and large-scale air entrainment

Hendrickson

Weymouth

et al. 2019

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…NFA predictions of a transom-stern flow are compared to laboratory measurements that have been performed at NSWCCD (see Dommermuth, et al 2008;Fu, et al 2008b;. The three-dimensional numerical simulations use 1408x768x384= 415,236,096 grid points which are distributed over 396 nodes on a Cray XT5 (Einstein at NAVO) and run for 31,000 time steps corresponding to 7.75 ship lengths.…”

Section: Air Entrainment and Free-surface Turbulence Of Transom Sternsmentioning

confidence: 99%

Computational Naval Ship Hydrodynamics

Brucker

Dommermuth

O'Shea

et al. 2010

2010 DoD High Performance Computing Modernization Program Users Group Conference

View full text Add to dashboard Cite

The primary purpose of our research efforts is to improve naval design and detection capabilities. Our current research efforts leverage HPC resources to perform high-resolution numerical simulations with hundreds of millions to billions of unknowns to study wave breaking behind a transom stern, wave-impact loading, the generation of spray by high-speed planing craft, air entrainment by plunging breaking waves, forced-motion, and storm seas. This paper focuses on the air entrainment and free-surface turbulence in the flow behind a transom-stern and wave-impact loading on marine platforms. Two codes, Numerical Flow Analysis (NFA) and Boundary Data Immersion Method (BDIM), are used in this study. Both codes are Cartesian-based LES formulations, and use either Volume of Fluid (VOF) (NFA) or conservative Volume of Fluid (cVOF) (BDIM) treatments to track the free-surface interface. The first project area discussed is the flow behind the transom stern. BDIM simulations are used to study the volume of entrained air behind the stern. The application of a Lagrangian bubble-extraction algorithm elucidates the location of air cavities in the wake and the bubble-size distribution for a flow that has over 10% void fraction. NFA simulations of the transom-stern flow are validated by comparing the numerical simulations to experiments performed at the Naval Surface Warfare Center Carderock Division (NSWCCD), where good agreement between simulations and experiments is obtained for mean elevations and regions of white water in the wake. The second project area discussed is wave impact loading, a topic driven by recent structural failures of highspeed planing vessels and other advanced vehicles, as well as the devastation caused by Tsunamis impacting low-lying coastal areas. NFA simulations of wave breaking events are compared to the NSWCCD cube impact experiments and the Oregon State University O.H. Hinsdale Wave Research Laboratories Tsunami experiments and it is shown that NFA is able to accurately simulate the propagation of waves over long distances after which it also accurately predicts highlyenergetic impact events.

show abstract

“…NFA predictions of the free-surface elevations near a transom-stern model moving with constant forward speed are compared to laboratory measurements that have been performed at the David Taylor Model Basin (DTMB) (see Fu, et al, 2008b). All length and velocity scales are respectively normalized by the model's length (L o ) and speed (U o ).…”

Section: Transom-stern Studiesmentioning

confidence: 99%