The numerical simulation of the influence of a reservoir water body on the Binchuan airgun source could provide a theoretical basis to analyze the data obtained from the active source detection and inversion of region...The numerical simulation of the influence of a reservoir water body on the Binchuan airgun source could provide a theoretical basis to analyze the data obtained from the active source detection and inversion of regional interior medium structures.Based on a medium model containing limited water body,we use the finite different method to simulate the effect of the water level,excitation energy and focal depth.The results show that the influence on the waveform amplitude caused by the water level changing is very large near the water body,and that a high water level or large amplitude change can have a larger effect.However,for stations beyond a certain epicentral distance,the influence will be weakened and kept stable.As for the Binchuan airgun source,amplitude fluctuation caused by the water level changing becomes very small(±0.05 times)after propagating a certain distance,so we can remove the influence of the water level changing by referring to the numerical simulation result.Wave amplitude increases linearly with the excitation energy and focal depth,therefore,the greater the energy and the deeper the focal depth,the better the effect of the excitation,and is more conducive in detecting remote and deep penetration underground structures.展开更多
Very Large Floating Structures (VLFS) have drawn considerable attention recently due to their potential significance in the exploitation of ocean resources and in the utilization of ocean space. Efficient and accurate...Very Large Floating Structures (VLFS) have drawn considerable attention recently due to their potential significance in the exploitation of ocean resources and in the utilization of ocean space. Efficient and accurate estimation of their hydroelastic responses to waves is very important for the design. Recently, an efficient numerical algorithm was developed by Ertekin and Kim (1999). However, in their analysis, the linear Level I Green-Naghdi (GN) theory is employed to describe fluid dynamics instead of the conventional linear wave (LW) theory of finite water depth. They claimed that this linear level I GN theory provided better predictions of the hydroelastic responses of VLFS than the linear wave theory. In this paper, a detailed derivation is given in the conventional linear wave theory framework with the same quantity as used in the linear level I GN theory framework. This allows a critical comparison between the linear wave theory and the linear level I GN theory. It is found that the linear level I GN theory can be regarded as an approximation to the linear wave theory of finite water depth. The consequences of the differences between these two theories in the predicted hydroelastic responses are studied quantitatively. And it is found that the linear level I GN theory is not superior to the linear wave theory. Finally, various factors affecting the hydroelastic response of VLFS are studied with the implemented algorithm.展开更多
基金jointly sponsored by the Earthquake Science and Technology Spark Program(XH18044Y)the National Natural Science Foundation of China(41474048,41574059)
文摘The numerical simulation of the influence of a reservoir water body on the Binchuan airgun source could provide a theoretical basis to analyze the data obtained from the active source detection and inversion of regional interior medium structures.Based on a medium model containing limited water body,we use the finite different method to simulate the effect of the water level,excitation energy and focal depth.The results show that the influence on the waveform amplitude caused by the water level changing is very large near the water body,and that a high water level or large amplitude change can have a larger effect.However,for stations beyond a certain epicentral distance,the influence will be weakened and kept stable.As for the Binchuan airgun source,amplitude fluctuation caused by the water level changing becomes very small(±0.05 times)after propagating a certain distance,so we can remove the influence of the water level changing by referring to the numerical simulation result.Wave amplitude increases linearly with the excitation energy and focal depth,therefore,the greater the energy and the deeper the focal depth,the better the effect of the excitation,and is more conducive in detecting remote and deep penetration underground structures.
基金by the National Natural Science Foundation of China(50039010)the Science and Technology Development Foundation of Shanghai Municipal Government(00XD14015)
文摘Very Large Floating Structures (VLFS) have drawn considerable attention recently due to their potential significance in the exploitation of ocean resources and in the utilization of ocean space. Efficient and accurate estimation of their hydroelastic responses to waves is very important for the design. Recently, an efficient numerical algorithm was developed by Ertekin and Kim (1999). However, in their analysis, the linear Level I Green-Naghdi (GN) theory is employed to describe fluid dynamics instead of the conventional linear wave (LW) theory of finite water depth. They claimed that this linear level I GN theory provided better predictions of the hydroelastic responses of VLFS than the linear wave theory. In this paper, a detailed derivation is given in the conventional linear wave theory framework with the same quantity as used in the linear level I GN theory framework. This allows a critical comparison between the linear wave theory and the linear level I GN theory. It is found that the linear level I GN theory can be regarded as an approximation to the linear wave theory of finite water depth. The consequences of the differences between these two theories in the predicted hydroelastic responses are studied quantitatively. And it is found that the linear level I GN theory is not superior to the linear wave theory. Finally, various factors affecting the hydroelastic response of VLFS are studied with the implemented algorithm.
