This dissertation deals with the internal waves generated by a submergedmoving body in stratified fluids by combining theoretical and experimental methods. Our purpose isto provide some scientific evidences for non-ac...This dissertation deals with the internal waves generated by a submergedmoving body in stratified fluids by combining theoretical and experimental methods. Our purpose isto provide some scientific evidences for non-acoustic detection of underwater moving bodies based onthe principles of dynamics of the internal waves. An approach to velocity potentials obtained bysuperposing Green''s functions of sources and sinks was proposed for Kelvin waves at the free surfaceor interface in a two-layer fluid. The effects of interacting surface- and internal-wave modesinduced by a dipole on the surface divergence field were investigated. A new theoretical modelformulating the interaction of a two-dimensional submerged moving body with the conjugate flow in athree-layer fluid was established. An exact solution satisfying the two-dimensional Benjamin-Onoequation was obtained and the vertically propagating properties of the weakly nonlinear long waveswere studied by means of the ray theory and WKB method. The above theoretical results arequalitatively consistent with those obtained in the experiments conducted by the author.展开更多
In this paper, the Extended Self Similarity (ESS) was used to study thescaling exponent ξ(q) of temperature data in the Reyleigh-Benard convection and its variation withexperimental measuring locations. The results s...In this paper, the Extended Self Similarity (ESS) was used to study thescaling exponent ξ(q) of temperature data in the Reyleigh-Benard convection and its variation withexperimental measuring locations. The results show that ξ(q) varies with locations and agrees wellwith experimental data. And then the wavelet transformation is used to extract the coherentstructure, by means of the definition of a called non-coherent signal. we can understand theinfluence of coherent structure on ξ(q) and the relations between large scale vortex motions andsmall ones.展开更多
文摘This dissertation deals with the internal waves generated by a submergedmoving body in stratified fluids by combining theoretical and experimental methods. Our purpose isto provide some scientific evidences for non-acoustic detection of underwater moving bodies based onthe principles of dynamics of the internal waves. An approach to velocity potentials obtained bysuperposing Green''s functions of sources and sinks was proposed for Kelvin waves at the free surfaceor interface in a two-layer fluid. The effects of interacting surface- and internal-wave modesinduced by a dipole on the surface divergence field were investigated. A new theoretical modelformulating the interaction of a two-dimensional submerged moving body with the conjugate flow in athree-layer fluid was established. An exact solution satisfying the two-dimensional Benjamin-Onoequation was obtained and the vertically propagating properties of the weakly nonlinear long waveswere studied by means of the ray theory and WKB method. The above theoretical results arequalitatively consistent with those obtained in the experiments conducted by the author.
文摘In this paper, the Extended Self Similarity (ESS) was used to study thescaling exponent ξ(q) of temperature data in the Reyleigh-Benard convection and its variation withexperimental measuring locations. The results show that ξ(q) varies with locations and agrees wellwith experimental data. And then the wavelet transformation is used to extract the coherentstructure, by means of the definition of a called non-coherent signal. we can understand theinfluence of coherent structure on ξ(q) and the relations between large scale vortex motions andsmall ones.
