The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Navid Mostoufi - One of the best experts on this subject based on the ideXlab platform.
-
Dynamics of two-Phase Flow in vertical pipes
Journal of Fluids and Structures, 2019Co-Authors: Ali Ebrahimi-mamaghani, Rahmat Sotudeh-gharebagh, Reza Zarghami, Navid MostoufiAbstract:Abstract In this study, a novel mathematical model was proposed for the dynamic analysis of two-Phase Flow in vertical pipes considering different two-Phase Flow models by including dissipative forces. To model the corresponding two-Phase Flow, common slip-ratio factors were utilized. The Galerkin discretization method and eigenvalue analysis were applied to solve the model equations. A detailed parametric analysis was also performed in order to elucidate the influence of various parameters such as volumetric gas fraction, Flow velocity, structural damping and gravity parameter on dynamics of the system, critical flutter velocities and frequencies. The model was validated with experimental data and simulation results reported in the literature It was concluded that the pipes conveying two-Phase Flow are prone to experience several dynamic phenomena. Stability of the pipe structure was also examined for different two-Phase Flow models and the results indicated that the instability boundaries are significantly affected by the choice of the model. Furthermore, it was shown that the dynamical response of the pipe is substantially dependent on the volumetric gas fraction. Hence, the gas volume fraction can be introduced as a fundamental parameter for the vibration control of the two-Phase Flow systems. The results of this study would be beneficial for engineers to optimally design suitable structures for two-Phase Flow systems.
Zhiming Lu - One of the best experts on this subject based on the ideXlab platform.
-
Stochastic analysis of transient three-Phase Flow in heterogeneous porous media
Stochastic Environmental Research and Risk Assessment, 2007Co-Authors: Mingjie Chen, Arturo A Keller, Zhiming LuAbstract:In this manuscript, we extend the stochastic analysis of transient two-Phase Flow (Chen et al., Water Resour Res 42:W03425, 2006) to three-Phase Flow, i.e., water, air, and NAPL. We use the van Genuchten model and the Parker and Lenhard three-Phase model to describe the relationships between Phase saturation, Phase relative permeability, and capillary pressure. The log-transformations of intrinsic permeability Y(x) = ln k(x), soil pore size distribution parameter βow(x) = ln αow(x) between water and NAPL, and βao(x) = ln αao(x) between air and NAPL, and van Genuchten fitting parameter \(\bar{n}({\bf x}) = \ln {\left[{n{\left({\bf x} \right)} - 1} \right]},\) are treated as stochastic variables that are normally distributed with a separable exponential covariance model. The Karhunen–Loeve expansion and perturbation method (KLME) is used to solve the resulting equations. We evaluate the stochastic model using two-dimensional examples of three-Phase Flow with NAPL leakage. We also conduct Monte Carlo (MC) simulations to verify the stochastic model. A comparison of results from MC and KLME indicates the validity of the proposed KLME application in three-Phase Flow. The computational efficiency of the KLME approach over MC methods is at least an order of magnitude for three-Phase Flow problems. This verified stochastic model is then used to investigate the sensitivity of fluid saturation variances to the input variances.
Emmanuel J. Candès - One of the best experts on this subject based on the ideXlab platform.
-
The Phase Flow method
Journal of Computational Physics, 2006Co-Authors: Lexing Ying, Emmanuel J. CandèsAbstract:This paper introduces the Phase Flow method, a novel, accurate and fast approach for constructing Phase maps for nonlinear autonomous ordinary differential equations. The method operates by initially constructing the Phase map for small times using a standard ODE integration rule and builds up the Phase map for larger times with the help of a local interpolation scheme together with the group property of the Phase Flow. The computational complexity of building up the complete Phase map is usually that of tracing a few rays. In addition, the Phase Flow method is provably and empirically very accurate. Once the Phase map is available, integrating the ODE for initial conditions on the invariant manifold only makes use of local interpolation, thus having constant complexity. The paper develops applications in the field of high frequency wave propagation, and shows how to use the Phase Flow method to (1) rapidly propagate wave fronts, (2) rapidly calculate wave amplitudes along these wave fronts, and (3) rapidly evaluate multiple wave arrival times at arbitrary locations.
Milorad P. Dudukovic - One of the best experts on this subject based on the ideXlab platform.
-
Two-Phase Flow distribution in 2D trickle-bed reactors
Chemical Engineering Science, 1999Co-Authors: Yi Jiang, M. R. Khadilkar, Muthanna H. Al-dahhan, Milorad P. DudukovicAbstract:An extended discrete cell model (DCM), based on minimization of energy dissipation rate, is applied to predict two-Phase Flow distribution in the two-dimensional trickle-bed reactors. The main advantages of DCM are that it can qualitatively capture the experimental observations, and readily distinguish between Flow distribution in prewetted and non-prewetted beds, as well as reflect the effects of bed structure and inlet liquid distributor on two Phase Flow distribution. For comparison purpose, the results of liquid distribution obtained by DCM are compared with both computational fluid dynamics (CFD) simulations and experimental observations in a 2D bed. The achieved qualitative and quantitative agreement justifies the use of DCM in predicting two Phase Flow distribution in packed beds. A particle wetting factor (f) has been introduced into DCM to account for the influence of particle surface wetting on liquid Flow distribution. Analysis of DCM simulations presented based on maldistribution factor (mf ) provides a convenient way of quantifying the effects of particle surface wetting, distributor design and bed depth on the two-Phase Flow field.
Ali Ebrahimi-mamaghani - One of the best experts on this subject based on the ideXlab platform.
-
Dynamics of two-Phase Flow in vertical pipes
Journal of Fluids and Structures, 2019Co-Authors: Ali Ebrahimi-mamaghani, Rahmat Sotudeh-gharebagh, Reza Zarghami, Navid MostoufiAbstract:Abstract In this study, a novel mathematical model was proposed for the dynamic analysis of two-Phase Flow in vertical pipes considering different two-Phase Flow models by including dissipative forces. To model the corresponding two-Phase Flow, common slip-ratio factors were utilized. The Galerkin discretization method and eigenvalue analysis were applied to solve the model equations. A detailed parametric analysis was also performed in order to elucidate the influence of various parameters such as volumetric gas fraction, Flow velocity, structural damping and gravity parameter on dynamics of the system, critical flutter velocities and frequencies. The model was validated with experimental data and simulation results reported in the literature It was concluded that the pipes conveying two-Phase Flow are prone to experience several dynamic phenomena. Stability of the pipe structure was also examined for different two-Phase Flow models and the results indicated that the instability boundaries are significantly affected by the choice of the model. Furthermore, it was shown that the dynamical response of the pipe is substantially dependent on the volumetric gas fraction. Hence, the gas volume fraction can be introduced as a fundamental parameter for the vibration control of the two-Phase Flow systems. The results of this study would be beneficial for engineers to optimally design suitable structures for two-Phase Flow systems.
