The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1%-2% of the free stream velocity,while in the conventional eN method,the N fact...The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1%-2% of the free stream velocity,while in the conventional eN method,the N factor is an empirical factor.In this paper the reliability of this key assumption in the improved eN method is checked by results of transition prediction by using the Parabolized Stability Equations(PSE).Transition locations of an incompressible boundary layer and a hypersonic boundary layer at Mach number 6 on a flat plate are predicted by both the improved eN method and the PSE method.Results from both methods agree fairly well with each other,implying that the transition criterion proposed in the improved eN method is reliable.展开更多
PS converted-waves （C-waves） have been commonly used to image through gas clouds but the C-wave imaging may also be degraded by the diodic effect introduced by the gas cloud. It may be compensated for using a veloci...PS converted-waves （C-waves） have been commonly used to image through gas clouds but the C-wave imaging may also be degraded by the diodic effect introduced by the gas cloud. It may be compensated for using a velocity perturbation method which decouples the diodic moveout into two parts： the base velocity and the velocity perturbation. Gas clouds are widely distributed in the Sanhu area in the Qaidam basin of northwest China which is rich in natural gas. A land 2D3C seismic dataset is analyzed from the Sanhu area and significant diodic effects are observed in the data which harm the C-wave imaging. The diodic correction is applied to this data and the resultant C-wave imaging and the details of the reservoir structure are significantly improved. The diodic moveout plays an important role in working out the residu~ shear wave statics and the association of diodie correction and shear wave residual statics computation is a key step of C-wave high fidelity imaging in the gas cloud area. Finally, the new process workflow with diodic moveout is given.展开更多
该文以交通流模型中不同平衡函数表达式为例,对一阶非线性双曲型方程组的自由项形式与数值解的色散性、耗散性之间关系,进行了数值模拟研究。结果发现:自由项对方程组数值解的色散性和耗散性影响都是比较有规律的,这种规律性在不同初始...该文以交通流模型中不同平衡函数表达式为例,对一阶非线性双曲型方程组的自由项形式与数值解的色散性、耗散性之间关系,进行了数值模拟研究。结果发现:自由项对方程组数值解的色散性和耗散性影响都是比较有规律的,这种规律性在不同初始密度条件下是不一样的;自由项导致方程组数值解色散或耗散强弱,与方程组的离散方式也有关,尤其在中等密度条件下。就Payne-W h itham模型方程,建议了能够对不同初始密度下扰动的传播和发展进行合理数值模拟的自由项和离散方式。展开更多
基金supported by the National Natural Science Foundation of China (Grant No.11002098)the National Basic Research Program of China (Grant No.2009CB724103)the Specialized Research Fund for the Doctoral Program of Higher Education
文摘The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1%-2% of the free stream velocity,while in the conventional eN method,the N factor is an empirical factor.In this paper the reliability of this key assumption in the improved eN method is checked by results of transition prediction by using the Parabolized Stability Equations(PSE).Transition locations of an incompressible boundary layer and a hypersonic boundary layer at Mach number 6 on a flat plate are predicted by both the improved eN method and the PSE method.Results from both methods agree fairly well with each other,implying that the transition criterion proposed in the improved eN method is reliable.
基金supported by the National Natural Science Foundation of China (No. 41074080)the Important National Science & Technology Specific Projects (No. 2011ZX05019-008)
文摘PS converted-waves （C-waves） have been commonly used to image through gas clouds but the C-wave imaging may also be degraded by the diodic effect introduced by the gas cloud. It may be compensated for using a velocity perturbation method which decouples the diodic moveout into two parts： the base velocity and the velocity perturbation. Gas clouds are widely distributed in the Sanhu area in the Qaidam basin of northwest China which is rich in natural gas. A land 2D3C seismic dataset is analyzed from the Sanhu area and significant diodic effects are observed in the data which harm the C-wave imaging. The diodic correction is applied to this data and the resultant C-wave imaging and the details of the reservoir structure are significantly improved. The diodic moveout plays an important role in working out the residu~ shear wave statics and the association of diodie correction and shear wave residual statics computation is a key step of C-wave high fidelity imaging in the gas cloud area. Finally, the new process workflow with diodic moveout is given.
文摘该文以交通流模型中不同平衡函数表达式为例,对一阶非线性双曲型方程组的自由项形式与数值解的色散性、耗散性之间关系,进行了数值模拟研究。结果发现:自由项对方程组数值解的色散性和耗散性影响都是比较有规律的,这种规律性在不同初始密度条件下是不一样的;自由项导致方程组数值解色散或耗散强弱,与方程组的离散方式也有关,尤其在中等密度条件下。就Payne-W h itham模型方程,建议了能够对不同初始密度下扰动的传播和发展进行合理数值模拟的自由项和离散方式。
