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Generation of three-dimensional fully nonlinear water waves by a submerged moving object / Chih-Hua Chang in Journal of engineering mechanics, Vol. 137 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Journal of engineering mechanics > Vol. 137 N° 2 (Fevrier 2011) . - pp.101-112 Titre : Generation of three-dimensional fully nonlinear water waves by a submerged moving object Type de document : texte imprimé Auteurs : Chih-Hua Chang, Auteur ; Keh - Han Wang, Auteur Année de publication : 2011 Article en page(s) : pp.101-112 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Three-dimensional  waves  Fully  nonlinear  wave  Moving  body  Wave  generation  Soliton. Résumé : This paper describes a numerical investigation on the generation of three-dimensional (3D) fully nonlinear water waves by a submerged object moving at speeds varied from subcritical to supercritical conditions in an unbounded fluid domain. Considering a semispheroid as the moving object, simulations of the time evolutions of 3D free-surface elevation and flow field are performed. The present 3D model results are found to agree reasonably well with other published vertical two-dimensional (2D) and quasi-3D numerical solutions using Boussinesq-type models. Different from the 2D cases with near critical moving speeds, the 3D long-term wave pattern suggests that in addition to the circularly expanded upstream advancing solitonlike waves, a sequence of divergent and transverse waves are also developed behind the moving object. The velocity distributions and associated fluid-particle trajectories at the free-surface and middle layers are presented to show the 3D feature of the motion. The results under various vertical positions (referred as gap) of a moving object are also compared. It is found the gap has shown a substantial influence on the generated waves, especially in the wake region, when an object moves at a near critical or subcritical speed. However, the results under the case with a high supercritical moving speed indicate the gap has a negligible effect on the generated upstream and downstream waves. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i2/p101_s1?isAuthorized=no [article] Generation of three-dimensional fully nonlinear water waves by a submerged moving object [texte imprimé] / Chih-Hua Chang, Auteur ; Keh - Han Wang, Auteur . - 2011 . - pp.101-112. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 137 N° 2 (Fevrier 2011) . - pp.101-112 Mots-clés : Three-dimensional  waves  Fully  nonlinear  wave  Moving  body  Wave  generation  Soliton. Résumé : This paper describes a numerical investigation on the generation of three-dimensional (3D) fully nonlinear water waves by a submerged object moving at speeds varied from subcritical to supercritical conditions in an unbounded fluid domain. Considering a semispheroid as the moving object, simulations of the time evolutions of 3D free-surface elevation and flow field are performed. The present 3D model results are found to agree reasonably well with other published vertical two-dimensional (2D) and quasi-3D numerical solutions using Boussinesq-type models. Different from the 2D cases with near critical moving speeds, the 3D long-term wave pattern suggests that in addition to the circularly expanded upstream advancing solitonlike waves, a sequence of divergent and transverse waves are also developed behind the moving object. The velocity distributions and associated fluid-particle trajectories at the free-surface and middle layers are presented to show the 3D feature of the motion. The results under various vertical positions (referred as gap) of a moving object are also compared. It is found the gap has shown a substantial influence on the generated waves, especially in the wake region, when an object moves at a near critical or subcritical speed. However, the results under the case with a high supercritical moving speed indicate the gap has a negligible effect on the generated upstream and downstream waves. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i2/p101_s1?isAuthorized=no

Study of solitary - wave - induced fluid motions and vortices in a cavity using a two - dimensional viscous flow model / Chih-Hua Chang in Journal of engineering mechanics, Vol.137 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of engineering mechanics > Vol.137 N° 11 (Novembre 2011) . - pp.769-778 Titre : Study of solitary - wave - induced fluid motions and vortices in a cavity using a two - dimensional viscous flow model Type de document : texte imprimé Auteurs : Chih-Hua Chang, Auteur ; Ted Chu, Auteur ; Wang, Keh-Han, Auteur Année de publication : 2012 Article en page(s) : pp.769-778 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Solitary  waves  Simulation  Imaging  techniques  Two-dimensional  models  Vortices Résumé : This study presents a combined numerical and experimental investigation of the free-surface variation and induced fluid motion for a solitary wave propagating past a submerged cavity (or trench). The formation of vortices and the trajectories of fluid particles showing the transport of fluid content within the cavity zone are examined. A two-dimensional viscous flow is simulated by solving the stream function and vorticity equations using the finite-analytic method. Equations of free-surface boundary conditions are discretized by a two-step finite-difference scheme. To obtain more detailed motions in a cavity, a transient boundary-fitted grid system with locally refined grids is adopted. Experimental measurements of the free-surface elevations and the visual observations of the vortex motion were carried out to compare to the numerical solutions. The simulated free-surface elevations and fluid particle motion at various times are found to agree reasonably well with measurements and recorded observations. The formation and subsequent growth of a pair of recirculating vortices around the front corner of the cavity are clearly simulated by the present model. The effects of cavity size and incident-wave height on the flow patterns and the transport displacement of the fluid particles along the vertical and horizontal directions are analyzed. The results indicate that the greater the incident-wave height, the larger the values of the horizontal and vertical transporting distances. With an increase of cavity length, the strength of induced up-rolling vortices and the amount of downstream transporting fluid particles increases. However, the depth of the cavity has an insignificant influence on the height of the up-rolling vortices. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i11/p769_s1?isAuthorized=no [article] Study of solitary - wave - induced fluid motions and vortices in a cavity using a two - dimensional viscous flow model [texte imprimé] / Chih-Hua Chang, Auteur ; Ted Chu, Auteur ; Wang, Keh-Han, Auteur . - 2012 . - pp.769-778. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol.137 N° 11 (Novembre 2011) . - pp.769-778 Mots-clés : Solitary  waves  Simulation  Imaging  techniques  Two-dimensional  models  Vortices Résumé : This study presents a combined numerical and experimental investigation of the free-surface variation and induced fluid motion for a solitary wave propagating past a submerged cavity (or trench). The formation of vortices and the trajectories of fluid particles showing the transport of fluid content within the cavity zone are examined. A two-dimensional viscous flow is simulated by solving the stream function and vorticity equations using the finite-analytic method. Equations of free-surface boundary conditions are discretized by a two-step finite-difference scheme. To obtain more detailed motions in a cavity, a transient boundary-fitted grid system with locally refined grids is adopted. Experimental measurements of the free-surface elevations and the visual observations of the vortex motion were carried out to compare to the numerical solutions. The simulated free-surface elevations and fluid particle motion at various times are found to agree reasonably well with measurements and recorded observations. The formation and subsequent growth of a pair of recirculating vortices around the front corner of the cavity are clearly simulated by the present model. The effects of cavity size and incident-wave height on the flow patterns and the transport displacement of the fluid particles along the vertical and horizontal directions are analyzed. The results indicate that the greater the incident-wave height, the larger the values of the horizontal and vertical transporting distances. With an increase of cavity length, the strength of induced up-rolling vortices and the amount of downstream transporting fluid particles increases. However, the depth of the cavity has an insignificant influence on the height of the up-rolling vortices. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.org/emo/resource/1/jenmdt/v137/i11/p769_s1?isAuthorized=no