A numerical study of nonlinear waves in a transcritical flow of stratified fluid past an obstacle

1992 ◽  
Vol 4 (10) ◽  
pp. 2230-2243 ◽  
Author(s):  
Hideshi Hanazaki
Keyword(s):  
Nonlinear Waves ◽  
Numerical Study ◽  
Stratified Fluid ◽  
Transcritical Flow

scholarly journals Numerical Study for Experiment on Wave Pattern of Internal Wave and Surface Wave in Stratified Fluid

2019 ◽  
Vol 33 (3) ◽  
pp. 236-244
Author(s):  
Ju-Han Lee ◽  
Kwan-Woo Kim ◽  
Kwang-Jun Paik ◽  
Won-Cheol Koo ◽  
Yeong-Gyu Kim
Keyword(s):  
Surface Wave ◽  
Internal Wave ◽  
Numerical Study ◽  
Wave Pattern ◽  
Stratified Fluid

scholarly journals A centre manifold approach to solitary waves in a sheared, stably stratified fluid layer

1996 ◽  
Vol 3 (2) ◽  
pp. 110-114 ◽  
Author(s):  
W. B. Zimmerman ◽  
M. G. Velarde
Keyword(s):  
Nonlinear Waves ◽  
Fluid Layer ◽  
Approximate Equation ◽  
Stratified Fluid ◽  
Material Surface ◽  
Centre Manifold ◽  
Wave Approximation ◽  
Long Wave ◽  
Long Wave Approximation ◽  
Energy Argument

Abstract. The centre manifold approach is used to derive an approximate equation for nonlinear waves propagating in a sheared, stably stratified fluid layer. The evolution equation matches limiting forms derived by other methods, including the inviscid, long wave approximation leading to the Korteweg- deVries equation. The model given here allows large modulations of the height of the waveguide. This permits the crude modelling of shear layer instabilities at the upper material surface of the waveguide which excite solitary internal waves in the waveguide. An energy argument is used to support the existence of these waves.

Numerical study of internal wave–wave interactions in a stratified fluid

2000 ◽  
Vol 415 ◽  
pp. 65-87 ◽  
Author(s):  
A. JAVAM ◽  
J. IMBERGER ◽  
S. W. ARMFIELD
Keyword(s):  
Internal Wave ◽  
Internal Waves ◽  
Numerical Study ◽  
Experimental Studies ◽  
Interaction Mechanism ◽  
Stratified Fluid ◽  
Interaction Region ◽  
Staggered Grid ◽  
Open Boundary ◽  
Wave Interactions

A finite volume method is used to study the generation, propagation and interaction of internal waves in a linearly stratified fluid. The internal waves were generated using single and multiple momentum sources. The full unsteady equations of motion were solved using a SIMPLE scheme on a non-staggered grid. An open boundary, based on the Sommerfield radiation condition, allowed waves to propagate through the computational boundaries with minimum reflection and distortion. For the case of a single momentum source, the effects of viscosity and nonlinearity on the generation and propagation of internal waves were investigated.Internal wave–wave interactions between two wave rays were studied using two momentum sources. The rays generated travelled out from the sources and intersected in interaction regions where nonlinear interactions caused the waves to break. When two rays had identical properties but opposite horizontal phase velocities (symmetric interaction), the interactions were not described by a triad interaction mechanism. Instead, energy was transferred to smaller wavelengths and, a few periods later, to standing evanescent modes in multiples of the primary frequency (greater than the ambient buoyancy frequencies) in the interaction region. The accumulation of the energy caused by these trapped modes within the interaction region resulted in the overturning of the density field. When the two rays had different properties (apart from the multiples of the forcing frequencies) the divisions of the forcing frequencies as well as the combination of the different frequencies were observed within the interaction region.The model was validated by comparing the results with those from experimental studies. Further, the energy balance was conserved and the dissipation of energy was shown to be related to the degree of nonlinear interaction.

On the three-dimensional internal waves excited by topography in the flow of a stratified fluid

1994 ◽  
Vol 263 ◽  
pp. 293-318 ◽  
Author(s):  
Hideshi Hanazaki
Keyword(s):  
Internal Waves ◽  
Numerical Study ◽  
Mach Reflection ◽  
Three Dimensional ◽  
Stratified Fluid ◽  
Linear Wave ◽  
Kp Equation ◽  
Subcritical Flow ◽  
Boussinesq Fluid ◽  
Upstream Waves

A numerical study of the three-dimensional internal waves excited by topography in the flow of a stratified fluid is described. In the resonant flow of a nearly two-layer fluid, it is found that the time-development of the nonlinearly excited waves agrees qualitatively with the solution of the forced KP equation or the forced extended KP equation. In this case, the upstream-advancing solitary waves become asymptotically straight crested because of abnormal reflection at the sidewall similar to Mach reflection. The same phenomenon also occurs in the subcritical flow of a nearly two-layer fluid. However, in the subcritical flow of a linearly stratified Boussinesq fluid, the two-dimensionalization of the upstream waves can be interpreted as the separation of the lateral modes due to the differences in the group velocity of the linear wave, although this does not mean in general that the generation of upstream waves is describable by the linearized equation.

A Numerical Study on the Performance of Fixed Oscillating Water Column Wave Energy Converter at Steep Waves

2016 ◽  
Author(s):  
Morteza Anbarsooz ◽  
Ali Faramarzi ◽  
Amirmahdi Ghasemi
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Nonlinear Waves ◽  
Numerical Study ◽  
Wave Length ◽  
Analytical Data ◽  
Absorption Efficiency ◽  
Numerical Results ◽  
Highly Nonlinear ◽  
Steep Waves

In the current study, a fully nonlinear two-dimensional numerical wave tank is developed using the commercial CFD software, Ansys Fluent 15.0, in order to study the absorption characteristics of an OWC at linear and highly nonlinear steep waves. The two-phase Volume-Of-Fluid (VOF) method is employed to predict the water free surface evolution. The numerical results are first validated against the available analytical data in the literature. The good agreement between the numerical results and those of analytics, revealed the capability of the developed numerical tank to study the performance of the OWC. Next, the simulations are performed for strongly nonlinear waves, up to the wave steepness of 0.069 (H/L=0.069), where H is the wave height and L is the wave length. The optimum pneumatic damping of the air turbine at such strongly steep and nonlinear waves is determined. Results show that the absorption efficiency of the OWC decreases considerably as the wave height increases. Moreover, the maximum wave energy absorption efficiency for the highly nonlinear waves occurs at a pneumatic damping coefficient lower than that of the linear theory.

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