12,813 research outputs found
Reducing Fluid Type Uncertainty with Well Test Analysis
Imperial Users onl
Stability analysis of slug flow control
The threat of slugging to production facilities has been known since the 1970s. This undesirable flow phenomenon continues to attract the attention of researchers and operators alike. The most common method for slug mitigation is by choking the valve at the exit of the riser which unfortunately could negatively affect production. The focus, therefore, is to satisfy the need for system stability and to maximize production simultaneously. Active feedback control is a promising way to achieve this. However, due to the complexity of multiphase flow systems, it is a challenge to develop a robust slug control system to achieve the desired performance using existing design tools. In this paper, a new general method for multiphase flow system stability analysis was proposed. Active feedback control was observed to optimize slug attenuation compared with manual choking. The use of soft sensors was believed to be desirable for the practical implementation of the proposed control technique
Modeling incompressible thermal flows using a central-moment-based lattice Boltzmann method
In this paper, a central-moment-based lattice Boltzmann (CLB) method for
incompressible thermal flows is proposed. In the method, the incompressible
Navier-Stokes equations and the convection-diffusion equation for the
temperature field are sloved separately by two different CLB equations. Through
the Chapman-Enskog analysis, the macroscopic governing equations for
incompressible thermal flows can be reproduced. For the flow field, the tedious
implementation for CLB method is simplified by using the shift matrix with a
simplified central-moment set, and the consistent forcing scheme is adopted to
incorporate forcing effects. Compared with several D2Q5
multiple-relaxation-time (MRT) lattice Boltzmann methods for the temperature
equation, the proposed method is shown to be better Galilean invariant through
measuring the thermal diffusivities on a moving reference frame. Thus a higher
Mach number can be used for convection flows, which decreases the computational
load significantly. Numerical simulations for several typical problems confirm
the accuracy, efficiency, and stability of the present method. The grid
convergence tests indicate that the proposed CLB method for incompressible
thermal flows is of second-order accuracy in space
Numerical implementation of a multiphase model for the analysis and design of reinforced slopes
International audienceA multiphase model is proposed for the elastoplastic analysis and design of soil structures reinforced by stiff linear inclusions, where shear and bending effects should be taken into account. A f.e.m-based numerical tool, incorporating a plasticity algorithm adapted to this multiphase model, is developed and illustrated on the example of a slope stabilized by such reinforcing inclusions. Emphasis is put in this analysis on the crucial role played by the shear and flexural behaviour of the inclusions in the slope stabilization
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