Flow through side-combined structure in a channel bend under subcritical flow regime

2020 ◽  
pp. 1-9
Author(s):  
Masoud Ghodsian ◽  
Farshid Feyzollahi ◽  
Mohammad Ghodsian
Keyword(s):  
Flow Regime ◽  
Subcritical Flow ◽  
Channel Bend ◽  
Combined Structure ◽  
Flow Through

A Review of Multiphase Flow Through Chokes

1997 ◽  
Vol 119 (1) ◽  
pp. 1-10 ◽  
Author(s):  
S. Rastoin ◽  
Z. Schmidt ◽  
D. R. Doty
Keyword(s):  
Multiphase Flow ◽  
Flow Regime ◽  
Flow Direction ◽  
Absolute Error ◽  
Average Absolute Error ◽  
Subcritical Flow ◽  
Common Purpose ◽  
Critical Flow Regime ◽  
Flow Through ◽  
Good Agreement

Three comprehensive mechanistic models (Ashford and Pierce, 1974; Sachdeva et al., 1986; Perkins, 1990) dealing with multiphase flow through chokes have been studied. Their common purpose is to determine the flow through a choke under both critical and subcritical flow. Except for their initial assumptions, these three models are basically the same and all are based on the energy equation. Performance of the model developed by Perkins (1990) was the best in a comparison test against a database of 1239 points. The other two models deviated up to 40 percent when compared to the Perkins model for large values of choke to pipe size ratios. A very important application of these models is in prediction of the pressure either upstream or downstream of the choke, given the flow rate through the choke and the known pressure. Pressure predictions against the flow direction (i.e., upstream of the choke) were foundto be in very good agreement with measurements. Not more than 13 percent average absolute error and 17 percent standard deviation were observed. Similar errors were reported for the downstream pressure predictions for data in the subcritical flow regime. However, downstream pressure predictions for data in the critical flow regime gave large errors, up to 40 percent, which were expected.

Darcy’s Experiments and the Deviation to Nonlinear Flow Regime

2000 ◽  
Vol 122 (3) ◽  
pp. 619-625 ◽  
Author(s):  
J. L. Lage ◽  
B. V. Antohe
Keyword(s):  
Flow Regime ◽  
Additional Data ◽  
Quadratic Extension ◽  
Nonlinear Flow ◽  
Data Set ◽  
Natural Processes ◽  
Darcy Equation ◽  
Flow Through ◽  
Cubic Extension ◽  
Consistent Parameter

Many important technological and natural processes involving flow through porous media are characterized by large filtration velocity. It is important to know when the transition from the linear flow regime to the quadratic flow regime actually occurs to obtain accurate models for these processes. By interpreting the quadratic extension of the original Darcy equation as a model of the macroscopic form drag, we suggest a physically consistent parameter to characterize the transition to quadratic flow regime in place of the Reynolds number, Re. We demonstrate that an additional data set obtained by Darcy, and so far ignored by the community, indeed supports the Darcy equation. Finally, we emphasize that the cubic extension proposed in the literature, proportional to Re3 and mathematically valid only for Re≪1, is irrelevant in practice. Hence, it should not be compared to the quadratic extension experimentally observed when Re⩾O1.[S0098-2202(00)01703-X]

A New Unified Diffusion—Viscous-Flow Model Based on Pore-Level Studies of Tight Gas Formations

SPE Journal ◽  
2012 ◽  
Vol 18 (01) ◽  
pp. 38-49 ◽  
Author(s):  
Mohammad R. Rahmanian ◽  
Roberto Aguilera ◽  
Apostolos Kantzas
Keyword(s):  
Porous Media ◽  
Viscous Flow ◽  
Flow Regime ◽  
Gas Flow ◽  
Flow Model ◽  
Molecular Flow ◽  
Single Element ◽  
Free Molecular Flow ◽  
Flow Through ◽  
Tight Porous Media

Summary In this study, single-phase gas-flow simulation that considers slippage effects through a network of slots and microfractures is presented. The statistical parameters for network construction were extracted from petrographic work in tight porous media of the Nikanassin Group in the Western Canada Sedimentary Basin (WCSB). Furthermore, correlations between Klinkenberg slippage effect and absolute permeability have been developed as well as a new unified flow model in which Knudsen number acts implicitly as a flow-regime indicator. A detailed understanding of fluid flow at microscale levels in tight porous media is essential to establish and develop techniques for economic flow rate and recovery. Choosing an appropriate equation for flow through a single element of the network is crucial; this equation must include geometry and other structural features that affect the flow as well as all variation of fluid properties with pressure. Disregarding these details in a single element of porous media can easily lead to flow misinterpretation at the macroscopic scale. Because of the wide flow-path-size distribution in tight porous media, a variety of flow regimes can exist in the equivalent network. Two distinct flow regimes, viscous flow and free molecular flow, are in either side of this flow-regime spectrum. Because the nature of these two types of flow is categorically different, finding/adjusting a unified flow model is problematic. The complication stems from the fact that the viscosity concept misses its meaning as the flow regime changes from viscous to free molecular flow in which a diffusion-like mechanism dominates. For each specified flow regime, the appropriate equations for different geometries are studied. In addition, different unified flow models available in the literature are critically investigated. Simulation of gas flow through the constructed network at different mean flow pressures leads to investigating the functionality of the Klinkenberg factor with permeability of the porous media and pore-level structure.

Effects of the Divergence Angle on the Onset of Asymmetric Flow Through a Planar Diffuser

2009 ◽  
Author(s):  
Majid Nabavi ◽  
Luc Mongeau
Keyword(s):  
Reynolds Number ◽  
Flow Regime ◽  
Critical Reynolds Number ◽  
Reynolds Numbers ◽  
Two Dimensional ◽  
Asymmetric Flow ◽  
Symmetric Flow ◽  
Turbulent Flow Regime ◽  
Flow Through ◽  
Gradual Expansion

In this study, two-dimensional laminar incompressible and turbulent compressible flow through the planar diffuser (gradual expansion) for different divergence half angles of the diffuser (θ), and different Reynolds numbers (Re) was numerically studied. The effects of θ on the critical Reynolds number at which the onset of asymmetric flow is observed, were investigated. In the laminar flow regime, it was observed that for every values of θ, there is a critical Re beyond which the flow is asymmetric. However, in the turbulent flow regime, for θ ≥ 20°, even at low Reynolds number the flow is asymmetric. Only for θ ≤ 10°, symmetric flow was observed below a critical Re.

Critical Resistance Affecting Sub- to Super-Critical Transition Flow by Vegetation

2019 ◽  
Vol 13 (01) ◽  
pp. 1950004 ◽  
Author(s):  
Ghufran Ahmed Pasha ◽  
Norio Tanaka
Keyword(s):  
Hydraulic Jump ◽  
Vegetation Density ◽  
Transition Flow ◽  
Great Resistance ◽  
Subcritical Flow ◽  
Stream Width ◽  
Critical Slope ◽  
Flow Through ◽  
Critical Resistance ◽  
Stream Direction

In order to design a vegetation structure to mitigate floods resulting from extreme events like tsunamis, vegetation density and thickness (width) are important parameters. Flow passing through vegetation faces great resistance, which results in a backwater rise on upstream (U/S) vegetation, increases the water slope inside the vegetation, and for some cases, forms a hydraulic jump downstream (D/S) of the vegetation, thus transforming a subcritical flow to supercritical [Pasha, G. A. and Tanaka, N. [2017] “Undular hydraulic jump formation and energy loss in a flow through emergent vegetation of varying thickness and density,” Ocean Eng. 141, 308–325.]. Like the concepts of critical velocity and critical slope, this paper introduces the concept of “critical resistance of vegetation,” which is defined as “resistance offered by vegetation that transforms a subcritical flow to supercritical.” An analytical approach to find the water depths U/S, inside, and D/S of vegetation is introduced and validated well by laboratory experiments. Critical resistance was determined against vegetation of variable densities ([Formula: see text], where [Formula: see text] of each cylinder in the cross-stream direction, [Formula: see text] of the cylinder), thicknesses (dn, where [Formula: see text] of a cylinder and [Formula: see text] of cylinders in a stream-wise direction per unit of cross-stream width), and the initial Froude number (Fro). A subcritical flow ([Formula: see text], without vegetation) was transformed to a supercritical flow (D/S vegetation) with a range of Froude numbers of 1.6–1.9, 1.1–1.2, and 0.85–0.98 against [Formula: see text] ratios of 0.25, 1.09, and 2.13, respectively, thus defining [Formula: see text] as the critical resistance. However, altering vegetation thickness did not change the results.

Diagnostic Technique for Quantitative Resolution of Three-Dimensional Liquid-Gas Phase Boundaries in Microchannel Flows

2013 ◽  
Author(s):  
Ravi S. Patel ◽  
Suresh V. Garimella
Keyword(s):  
Flow Regime ◽  
Capillary Tube ◽  
Three Dimensional ◽  
Diagnostic Technique ◽  
Immiscible Fluids ◽  
Microchannel Flow ◽  
Two Phase ◽  
Gas Phases ◽  
Position Data ◽  
Flow Through

The morphology of liquid-gas interfaces in adiabatic two-phase microchannel flow through a transparent acrylic microchannel of 500 μm × 500 μm square cross section is investigated. Water seeded with 0.5 μm-diameter fluorescent polystyrene particles is pumped through the channel, and the desired adiabatic two-phase flow regime is achieved through controlled air injection. The diagnostic technique relies on obtaining particle position data through epifluorescent imaging of the flow at excitation and emission wavelengths of 532 and 620 nm, respectively. The particle positions are then used to resolve interface locations to within ±2 μm in the viewing plane. This technique was previously demonstrated by the authors for a static meniscus in a capillary tube. The complete interface geometry between liquid and gas phases is obtained for operation in the annular flow regime by mapping the interface within individual focal planes at various depths within the channel. The diagnostic technique is shown to successfully locate and measure interfaces between transparent, immiscible fluids in a dynamic microchannel flow environment.

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