Natural debris floods travel in straight and meandering courses. The flow behaviour greatly depends on the volume fractions of solid and fluid, as well as on their dynamic interactions with the channel geometry. For the quasi three-dimensional simulations of flow dynamics and mass transport of these floods through meandering and straight channels, we employ a two-phase debris flow model to carry out simulations for debris floods within straight and sine-generated meandering channels of different amplitudes. The results for different sinuous meandering paths are compared with that in the straight one in terms of phase velocity, downslope advection and dispersion, depths of the maxima, deposition of mass, position of front and rear parts of the solid and fluid phases, and also the flow dynamics out of the conduits. The results reveal the slowing of the flow and increase of momentary deposition of the mixture mass in the vicinity of the bends along with the increasing sinuosity. The numerical experiments are useful to better understand the dynamics of debris floods down meandering channels as seen in the natural paths of the rivers as well as already existing channels like episodic rivers in hilly regions. The results can be extended to propose some appropriate mitigation strategies.

The lattice Boltzmann models, especially the pseudopotential models, have been developed to investigate multicomponent Multiphase fluids in presence of phase change process. However, the interparticle force between different components causes compressibility error in the non-phase-change component. This restricts the model capability in quantitative analysis of the physical foaming process, such as expansion rate and decay time. In the present study, a multicomponent Multiphase pseudopotential phase change model (the MMPPCM) is improved by introducing an effective mass form of high-pressure-difference multicomponent model in the non-phase-change component. The improved model is compared with the MMPPCM based on simulations of the phase change process of static and moving fluids, as well as the physical foaming process. Density variation of non-phase-change component and its effect on flow field characteristics are analyzed during the phase change process. Simulation results of physical foaming process lead to about 10% ~ 20% reduction of the compressibility error for the improved model as compared with the results of MMPPCM. The improved model also enhances the computational stability of phase change simulation of the static droplets.

In this paper experimental and computational modeling methods for studying Multiphase flows in porous and fractured media are studied. Particular attention was given to the flows in a laboratory-scale flow cell model. It is shown that the gas-liquid flows generate fractal interfaces and the viscous and capillary fingering phenomena are discussed. Experimental data concerning the displacement of two immiscible fluids in the lattice-like flow cell are presented. The flow pattern and the residual saturation of the displaced fluid during the displacement are discussed. Numerical simulations results of the experimental flow cell are also presented. The numerical simulation results for single and Multiphase flows through rock fractures are also presented. Fracture geometry studied was obtained from a series of CT scan of an actual fracture. Computational results show that the major losses occur in the regions with smallest apertures. An empirical expression for the fracture friction factor is also described. Applications to CO2 sequestration in underground brine fields depleted oil reservoir stimulation are discussed.    

This work proposes a novel method to find the phase error and oscillation amplitude in Multiphase LC oscillators. A mathematical approach is used to find the relationship between every stage's output phase and its coupling factor. To much more general analysis, every stage assumed to have a different coupling factor. The mismatches in LC tanks are considered as the main source of phase errors and accordingly the phase deviation of each stage is calculated in a distinct equation. Then, the amplitude of oscillation for each stage is individually derived using phase error results. Not only considering different coupling factors increases the generality of this work but also the results are in better conformance with simulations compared to previous works. The theoretical results are evaluated and confirmed through extensive simulations using ADS software.

Simulation of the in-situ combustion process is one of the most complex simulations amongst other reservoir flow simulations. Accurate simulation of the process is critical to obtain a successful implementation of the in-situ combustion process. Several factors impact performance of the simulation of this process. First are all the numerical models used for different sub-processes, such as reactions, fluid phase behavior, heat loss to surrounding formations and fluid physical properties. In the previous numerical models of the in-situ combustion process, very simplified models were used for the phase behavior of the fluid. Recent studies show that the fluid phase behavior model has a great effect on the results of the simulation. In this work, a novel simulator is presented, which uses a rigorous phase equilibrium model for fluid phase behavior calculations. The numerical model is developed in such a way that different models for the phenomena mentioned above can be replaced easily. The other affecting parameter is the solution scheme of the simulator. Previous studies indicated that the more implicit the solution scheme, the better the performance of the simulator. The presented simulator uses a full implicit solution scheme to solve the equations. The applicability of this method is examined through two synthetic reservoirs.