In the present paper. a two -fluid model with interphase coupling effects is appliedto dilute gas-particle systems.In order to study,the characteristics of shock diffraction round a sharp 90 degree corner in the dust...In the present paper. a two -fluid model with interphase coupling effects is appliedto dilute gas-particle systems.In order to study,the characteristics of shock diffraction round a sharp 90 degree corner in the dusty gas, we adopt the operator-spliting technique and high-resolution numerical method,reveal the changes of diffractionpattern due to particle presence,and discuss the effects of particle properties onpost-shock flow field展开更多
Numerical Fresnel diffraction is broadly used in optics and holography in particular.So far,it has been implemented using convolutional approaches,spatial convolutions,or the fast Fourier transform.We propose a new wa...Numerical Fresnel diffraction is broadly used in optics and holography in particular.So far,it has been implemented using convolutional approaches,spatial convolutions,or the fast Fourier transform.We propose a new way,to our knowledge,of computing Fresnel diffraction using Gabor frames and chirplets.Contrary to previous techniques,the algorithm has linear-time complexity,does not exhibit aliasing,does not need zero padding,has no constraints on changing shift/resolution/pixel pitch between source and destination planes,and works at any propagation distance.We provide theoretical and numerical analyses,detail the algorithm,and report simulation results with an accelerated GPU implementation.This algorithm may serve as a basis for more flexible,faster,and memory-efficient computer-generated holography methods.展开更多
This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and break...This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.展开更多
In this letter, we propose a method for the numerical calculations of the femtosecond laser pulse passed through a subwavelength aperture. The time-dependent laser pulse is decomposed into a series of monochromatic si...In this letter, we propose a method for the numerical calculations of the femtosecond laser pulse passed through a subwavelength aperture. The time-dependent laser pulse is decomposed into a series of monochromatic simple harmonic waves. For the light field of the harmonic wave with a single frequency, the numerical calculation is made based on the solution of the Green's integral equation set of the electromagnetic waves. Such numerical solution is iterated for all the waves with different frequencies, and all the numerical solutions are transformed into the light fields in the time domain by inverse Fourier transform. The light intensity distributions transmitted the subwavelength aperture are calculated and the results show the propagation of the light field is along the direction of the medium interface.展开更多
文摘In the present paper. a two -fluid model with interphase coupling effects is appliedto dilute gas-particle systems.In order to study,the characteristics of shock diffraction round a sharp 90 degree corner in the dusty gas, we adopt the operator-spliting technique and high-resolution numerical method,reveal the changes of diffractionpattern due to particle presence,and discuss the effects of particle properties onpost-shock flow field
基金Fonds Wetenschappelijk Onderzoek(12ZQ223N,G089424N,G0A3O24N)Japan Society for the Promotion of Science(International research fellow P22752)。
文摘Numerical Fresnel diffraction is broadly used in optics and holography in particular.So far,it has been implemented using convolutional approaches,spatial convolutions,or the fast Fourier transform.We propose a new way,to our knowledge,of computing Fresnel diffraction using Gabor frames and chirplets.Contrary to previous techniques,the algorithm has linear-time complexity,does not exhibit aliasing,does not need zero padding,has no constraints on changing shift/resolution/pixel pitch between source and destination planes,and works at any propagation distance.We provide theoretical and numerical analyses,detail the algorithm,and report simulation results with an accelerated GPU implementation.This algorithm may serve as a basis for more flexible,faster,and memory-efficient computer-generated holography methods.
基金supported by the National Natural Science Foundation of China (50879085)the Program for New Century Excellent Talents in University(NCET-07-0778)Fundamental Research Funds for the Central Universities (2012QNA4020)
文摘This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.
文摘In this letter, we propose a method for the numerical calculations of the femtosecond laser pulse passed through a subwavelength aperture. The time-dependent laser pulse is decomposed into a series of monochromatic simple harmonic waves. For the light field of the harmonic wave with a single frequency, the numerical calculation is made based on the solution of the Green's integral equation set of the electromagnetic waves. Such numerical solution is iterated for all the waves with different frequencies, and all the numerical solutions are transformed into the light fields in the time domain by inverse Fourier transform. The light intensity distributions transmitted the subwavelength aperture are calculated and the results show the propagation of the light field is along the direction of the medium interface.
