The Adomian decomposition method(ADM) is an approximate analytic method for solving nonlinear equations. Generally, an approximate solution can be obtained by using only a few terms. However, in applications, we need to use it flexibly according to the real problem. In this paper, based on the ADM, we give a modified asymptotic Adomian decomposition method and use it to solve the nonlinear Boussinesq equation describing groundwater flows. The example shows effectiveness of the modified asymptotic Adomian decomposition method.
Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under different wind directions. Further, an unstructured-grid, three-dimensional finite-volume coastal ocean model(FVCOM) is applied to investigate the wind-induced currents and the transport process to explain the reason why algal blooms occur at the detected places. We first deduce the primary distribution of biomass from overlaid satellite images, and explain the formation mechanism by analyzing the pollution sources, and simulating the flow field and transportation process under prevailing wind over Chaohu Lake. And then, we consider the adjustment action of the wind on the corresponding day and develop a two-time scale approach to describe the whole formation process of algae horizontal distribution in Chaohu Lake. That is, on the longer time scale, i.e., during bloom season, prevailing wind determines the primary distribution of biomass by inducing the characteristic flow field; on the shorter time scale, i.e., on the day when bloom occurs, the wind force adjusts the primary distribution of biomass to form the final distribution of algal bloom.
The flow through a single fracture is numerically studied by means of the Fluent Software. The results show that the roughness of the fracture significantly affects the hydraulic conductivity in the fracture as compared with the cubic law model widely used to describe the flow between two smooth parallel plates. A new model is proposed in this paper, the non-symmetric sinusoidal fracture model, to simulate the flow in a real fracture. This model involves two sinusoidal-varying walls with different phases to replace the flat planes in the cubic law model. The relationships between the effective hydraulic apertures and the phase retardation for different relative amplitudes and wavelengths are numerically investigated. A simple expression of the effective hydraulic aperture of the fracture is obtained, together with the law of the effective hydraulic aperture against the amplitude, the phase retardation and the wavelength of two sinusoidal-varying walls.
Surface water-blooms (SWBs) is usually explained as a buoyant migration of blue-green algae to the water surface under the conditions of reduced turbulence. Wind-induced turbulent mixing can cause considerable heterogeneity in the vertical concentration distribution of algal cells. There exists a criterion below which cell buoyancy can overcome the turbulent mixing. Former researchers regarded a certain wind speed as this criterion, but this wind speed differs in value. In this research, we propose a new criterion, nondimensional entrainment number (En), which represents the ratio of the intrinsic velocity of algal cells relative to the characteristic velocity of wind-induced mixing. Observation in Taihu Lake demonstrates that this new criterion is more suitable for the description of hydrodynamic effect on the formation of surface water-blooms.
