Begell House
Journal of Porous Media
Journal of Porous Media
1091-028X
2
2
1999
Downslope Movement of Compositionally Driven Gravity Flows over Porous Surfaces
In many situations that involve gravity current flows over surfaces these same surfaces may not be impervious to the passage of fluid and so should be treated as porous media. The volumetric flux of fluid through the porous bottom may, in turn, have a profound effect on the structure as well as the spatiotemporal evolution of the current, influencing such things as rate and extent of spreading and the formation of internal bores. It is our intention here to present a model for the passage of heavy fluids down porous slopes under lighter ambient fluids surmounted by a free surface. The equations that describe these two-layer flows are derived from the Navier—Stokes equations in the small aspect ratio flow regime. We consider constant density inviscid fluids, neglecting surface tension and entrainment between the layers. The bottom boundary condition is designed to allow for a volumetric flux of fluid from the gravity current across the sloping bottom boundary. We study fixed volume releases of heavy fluid as we believe that such flows represent an appropriate paradigm for many atmospheric, oceanic, and human-made gravity currents. Various parameter regimes for these flows are explored numerically and the accuracy of the numerical procedure is examined. Comparison of our model-based numerical computations of the distance to extinction of this fully time-dependent bottom flow with the reported experimental results indicates both that our model captures the salient features of such flows and that our numerical scheme is accurate.
T.B.
Moodie
Institute of Geophysics, Meteorology and Space Physics and Department of Mathematical Sciences, Applied Mathematics Institute, University of Alberta, Edmonton, Alberta, Canada T6G 2G1
J. P.
Pascal
Department of Mathematical Sciences, Applied Mathematics Institute, University of Alberta, Edmonton, Alberta, Canada T6G 2G1
127-141
Water Alternating Gas Injection: Laboratory Measurement and Comparison with Analytical Calculation
Water alternating gas injection has been proposed as a method to increase reservoir oil recovery; however, the three-phase flow occurring in this process is somewhat difficult to describe, and many basic data are needed, including the three-phase relative permeabilities. We present measurements from petrophysical data, flowing tests, and analytical calculations for a three-phase flow process. The displacements have been conducted in a steady-state mode. In the analytical calculations we use the water, oil, and gas continuity equations. We solve this hyperbolic system of partial differential equations by the method of characteristics and symbolic calculation facilities. The literature describes the methodology to calculate bank propagation. Here we use a similar methodology to compare the experimental and analytical results to access the validity of the methodology.
C.
Cunha
Department of Mechanical Engineering, Campinas State University, Caixa Postal 6052, 13083 Campinas-SP, Brazil
E. J.
Bonet
Department of Petroleum Engineering, State University of Campinas, UNICAMP, Ch P. 6122, Campinas, San Paulo, 13083-970, Brazil
A. C.
Correa
Department of Mechanical Engineering, Campinas State University, Caixa Postal 6052, 13083 Campinas-SP, Brazil
143-151
Numerical Predictions of Porous Burners with Integrated Heat Exchanger for Household Applications
A numerical method for the calculation of premixed methane combustion and heat transfer in porous burners with built-in heat exchangers is presented. The flow, temperature, and major species concentration fields were calculated by solving the mass, momentum, gas, and solid energy and species conservation equations. Nonequilibrium between the gas and solid phases was considered by using separate energy equations for the gas and the solid and by coupling them through a convective heat transfer coefficient. The porous medium was assumed to emit, absorb, and isotropically scatter radiation. Centerline gas and solid temperatures were compared with available experimental data obtained for two different burner configurations. The results show reasonable accuracy, indicating that the present algorithm is a valid tool for future engineering design.
Isabel
Malico
Department of Physics, University of Évora, R, Romão Ramalho, 59, 7000-671, Évora, Portugal ; IDMEC/IST, Department of Mechanical Engineering, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
Jose C. F.
Pereira
Mechanical Engineering Department Instituto Superior Tecnico Av. Rovisco Pais, 1049-001 Lisboa Portugal
153-162
A Model of Colmatation Suffosion Filtration
A model of the dispersion filtration system in porous media is presented that takes into account the colmatation and suffosion of pore effects. Problems are formulated to describe filtration with a given regime of filtration velocity and given pressures on the ends of the bed regimes and are solved numerically. The influence of the diffusion coefficient and the colmatation and suffosion parameters on the particle concentration in the flow, the current porosity profiles, the filtration velocity, and other characteristics are analyzed.
B. Kh.
Khuzhayorov
Complex Research Institute of Regional Problems, Academy of Science of Uzbekistan, Uzbekistan
163-172
A Study of Gas Liquid Liquid Systems in a Gas-Agitated Extractor with Static Mixer
The operational characteristics of a gas−liquid−liquid system in a gas-agitated extractor with static mixer were studied. Experimental measurements of the gas holdup, the holdup of the dispersed phase, and the mass transfer coefficient under varying conditions were obtained out in the extractor using air, water, and kerosene. It was found that the holdup of the dispersed phase and the mass transfer coefficient depend on gas velocity, water velocity, kerosene velocity, and the structure within extractor. The holdup of gas is independent of the water velocity and kerosene velocity.
Xiaoguang
Ren
Department of Chemical and Process Engineering, University of Surrey, Guildford GU2 5XH, UK
Yongji
Song
Liaoyang Petrochemical Engineering Institute, Liaoyang, 111003, P. R. China
Changhou
Liu
School of Chemical Eng., Dalian University of Technology, Dalian, 116012, P.R. China
173-178
Fully Developed Free Convection in Open-Ended Vertical Channels Partially Filled with Porous Material
Analytical solutions for fully developed natural convection in open-ended vertical channels partially filled with porous substrates are presented. Four fundamental boundary conditions have been investigated and the corresponding fundamental solutions computed. These four fundamental boundary conditions were obtained by combining each of the two conditions of one boundary maintained at uniform heat flux and one at uniform wall temperature; in each condition the opposite boundary is kept adiabatic or isothermal at the inlet fluid temperature. Expressions for the fully developed velocity, temperature, mixing cup temperature, volumetric flow rate, friction coefficient, and Nusselt number are given for each fundamental solution. Such fully developed values are approached, in a given channel, when the height-to-gap width ratio is sufficiently large. These values represent the limiting conditions and provide analytical checks on numerical solutions for steady and transient developing flows.
O. M.
Haddad
Department of Mechanical Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan
179-189
Flow Modeling in Fabric Filters
In this article, after a short description of the general characteristics of fabric filters, the methods to evaluate pressure drop found in the literature are briefly surveyed. To provide a contribution toward a more detailed characterization of fabric filter performance, a one-dimensional time-dependent mathematical model has been developed for both inside−outside and outside−inside gas flow in the bag. Direction of the gas flow in the bag is representative of fabric filter cleaning methods (i.e., shaker, reverse-air, pulse-jet). The resulting simulation model allows for a fairly precise estimation of pressure, velocity, and dust cake fields inside the filter, supported by comparisons with experimental data. Using this simulation tool, the baghouse system design based on economic optimization may be pursued. With this in mind, a mapping example of main operational parameters is presented with the aim of highlighting the capabilities of the proposed methodological approach.
Antonio C.
Caputo
Department of Energetics, Faculty of Engineering, University of L’Aquila, 67040 Monteluco di Roio (AQ), L’Aquila, Italy
Pacifico M.
Pelagagge
Department of Energetics, Faculty of Engineering, University of L’Aquila, 67040 Monteluco di Roio (AQ), L’Aquila, Italy
191-204