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Hydro-meteorology
Published in Amithirigala Widhanelage Jayawardena, Fluid Mechanics, Hydraulics, Hydrology and Water Resources for Civil Engineers, 2021
Amithirigala Widhanelage Jayawardena
Hydrostatic equilibrium occurs when the pressure gradient forces balance the gravity forces. Thus there is no acceleration, and the air moves with constant velocity upwards or downwards.
Numerical analysis of pile foundation in liquefiable soils: parametric study
Published in International Journal of Geotechnical Engineering, 2021
The analysis of centrifuge testing modelling was performed in four steps. In the first step, analysis was carried out subjected to soil skeleton and pore water weight. After full loading and reaching the static and hydrostatic equilibrium, pore pressure and stress values were used as initial values for the second stage of analysis. In the second step, the weight of the pile and the superstructure was introduced into the model by plastic analysis. In the third step, earthquake loading was applied to the model. The time step for applying the Kobe earthquake to the model at this stage was considered to be 0.005 s. Given that the duration of the earthquake is 20 s and after the earthquake loading, in the fourth stage of analysis, the drainage was allowed for the pore water to reach the hydrostatic equilibrium conditions for 5 s. The 5000 analysis stages equal to the time of 25 s were considered for the analysis of the model in the third and fourth stages of the analysis. In dynamic analysis for numerical integration of differential equations, the Newmark method was used with integration parameters γ = 0.5 and β = 0.25. The Modified Newton–Raphson algorithm was used to solve the system of equations.
Exsolving two-phase flow in oil wells
Published in Geophysical & Astrophysical Fluid Dynamics, 2020
Victoria E. Pereira, Andrew C. Fowler
Hydrocarbon extraction requires a complex production system, both below and above ground. Multiple wells will be drilled down to the reservoir level. High pressures at the base and low pressures at the surface result in the reservoir fluid travelling up through the wells. This primary recovery driven by the initial reservoir pressure is known as natural lift. Over time, due to production, the reservoir pressure will decrease and the pressure gradient will tend towards hydrostatic equilibrium which results in reduced flow into the well. The flow can be encouraged by means of artificial lift systems which aim to increase the local energy in the well (Golan and Whitson 1991), and secondary recovery methods aimed at increasing the reservoir pressure (Muggeridge et al.2014).
On the dynamics of an idealised bottom density current overflowing in a semi-enclosed basin: mesoscale and submesoscale eddies generation
Published in Geophysical & Astrophysical Fluid Dynamics, 2020
Mathieu Morvan, Xavier Carton, Pierre L'Hégaret, Charly de Marez, Stéphanie Corréard, Stéphanie Louazel
The mesoscale eddies are initialised following the procedure in Ciani et al. (2016) and Morvan et al. (2019). The velocity field of each eddy is defined as with , , typical values found in the Gulf of Aden (Bower and Furey 2012). Then, the pressure field is computed via the cyclo-geostrophic balance as described in Ciani et al. (2016). The density anomalies associated with the mesoscale eddies are computed using the hydrostatic equilibrium. Mesoscale eddies are separated by 150 km from each other and by 100 km from the southern and northern coasts (see figure 4).