共查询到20条相似文献,搜索用时 171 毫秒
1.
V. V. Murzenko 《Fluid Dynamics》1994,29(2):214-220
The plane steady flow of a homogeneous fluid between several wells in a reservoir zone containing hydrofractures is considered.
Under the assumption of infinite fracture conductivity, analytic solutions of the Laplace equation for the pressure distribution
in the elements of several typical symmetrical well arrangements are obtained, thus enabling them to be compared. Since the
conductivity of the fracture may have a significant effect on the flow, the influence of its hydraulic properties on the productivity
of a producing well is numerically investigated.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 74–82, March–April, 1994. 相似文献
2.
Steady flow of homogeneous fluid in an oil reservoir recovery element with a hydrofracture 总被引:1,自引:0,他引:1
The plane problem of steady flow of a homogeneous fluid in a five-point oil reservoir recovery element with a hydrofracture
of finite conductivity is considered. It is assumed that the motion of the fluid in the reservoir and in the fracture obeys
a linear resistance law and that the permeability of the reservoir and the effective permeability of the fracture are sharply
different. Analytic solutions are obtained for the case of an ideal fracture (fracture of infinite conductivity). The flows
are analyzed numerically with allowance for the finite conductivity of the fracture.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.1, pp. 104–112, January–February,
1994. 相似文献
3.
João Eduardo Borges Nuno H. C. Pereira Jorge Matos Kathleen H. Frizell 《Experiments in fluids》2010,48(1):17-31
The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously
the magnitude and direction of the velocity vector in complex air–water flows, is described in this paper. The air–water flows
envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton
and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the
conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was
placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration
procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in
the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing
the velocity field of other complex air–water flows. 相似文献
4.
Souzanna Sofou Edward B. Muliawan Savvas G. Hatzikiriakos Evan Mitsoulis 《Rheologica Acta》2008,47(4):369-381
Bread dough (a flour–water system) has been rheologically characterized using a parallel-plate, an extensional, and a capillary
rheometer at room temperature. Based on the linear and nonlinear viscoelastic and viscoplastic data, two constitutive equations
have been applied, namely a viscoplastic Herschel–Bulkley model and a viscoelastoplastic K–BKZ model with a yield stress.
For cases where time effects are unimportant, the viscoplastic Herschel–Bulkley model can be used. For cases where transient
effects are important, it is more appropriate to use the K-BKZ model with the addition of a yield stress. Finally, the wall
slip behavior of dough was studied in capillary flow, and an appropriate slip law was formulated. These models characterize
the rheological behavior of bread dough and constitute the basic ingredients for flow simulation of dough processing, such
as extrusion, calendering, and rolling. 相似文献
5.
B. L. Smorodin 《Journal of Applied Mechanics and Technical Physics》1998,39(1):60-64
For a rotating liquid layer with boundaries of low thermal conductivity, an amplitude equation is obtained that describes
the evolution of secondary convective flows in uniform heating and above a hot spot. The dependence of the coefficients of
the amplitude equation on the rotation parameter, Prandtl number, and heat-flux nonuniformity is obtained. The influence of
rotation on the stability of nonlinear regimes is analyzed for uniform heating. The boundaries of flow stability are investigated
for variously shaped hot spots.
Perm'State University, Perm'614600. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika. Vol. 39, No. 1, pp. 69–74,
January–February, 1998. 相似文献
6.
Mohamed Abd El-Aziz 《Meccanica》2007,42(4):375-386
An analysis has been carried out to obtain the flow, heat and mass transfer characteristics of a viscous electrically conducting
fluid having temperature dependent viscosity and thermal conductivity past a continuously stretching surface, taking into
account the effect of Ohmic heating. The flow is subjected to a uniform transverse magnetic field normal to the plate. The
resulting governing three-dimensional equations are transformed using suitable three-dimensional transformations and then
solved numerically by using fifth order Runge–Kutta–Fehlberg scheme with a modified version of the Newton–Raphson shooting
method. Favorable comparisons with previously published work are obtained. The effects of the various parameters such as magnetic
parameter M, the viscosity/temperature parameter θ
r
, the thermal conductivity parameter S and the Eckert number Ec on the velocity, temperature, and concentration profiles, as well as the local skin-friction coefficient, local Nusselt number,
and the local Sherwood number are presented graphically and in tabulated form. 相似文献
7.
Accurate models of multiphase flow in porous media and predictions of oil recovery require a thorough understanding of the
physics of fluid flow. Current simulators assume, generally, that local capillary equilibrium is reached instantaneously during
any flow mode. Consequently, capillary pressure and relative permeability curves are functions solely of water saturation.
In the case of imbibition, the assumption of instantaneous local capillary equilibrium allows the balance equations to be
cast in the form of a self-similar, diffusion-like problem. Li et al. [J. Petrol. Sci. Eng. 39(3) (2003), 309–326] analyzed oil production data from spontaneous countercurrent imbibition experiments and inferred that
they observed the self-similar behavior expected from the mathematical equations. Others (Barenblatt et al. [Soc. Petrol. Eng. J. 8(4) (2002), 409–416]; Silin and Patzek [Transport in Porous Media 54 (2004), 297–322]) assert that local equilibirum is not reached in porous media during spontaneous imbibition and nonequilibirium
effects should be taken into account. Simulations and definitive experiments are conducted at core scale in this work to reveal
unequivocally nonequilbirium effects. Experimental in-situ saturation data obtained with a computerized tomography scanner
illustrate significant deviation from the numerical local-equilibrium based results. The data indicates: (i) capillary imbibition
is an inherently nonequilibrium process and (ii) the traditional, multi-phase, reservoir simulation equations may not well
represent the true physics of the process. 相似文献
8.
A numerical investigation of the steady-state, laminar, axi-symmetric, mixed convection heat transfer in the annulus between
two concentric vertical cylinders using porous inserts is carried out. The inner cylinder is subjected to constant heat flux
and the outer cylinder is insulated. A finite volume code is used to numerically solve the sets of governing equations. The
Darcy–Brinkman–Forchheimer model along with Boussinesq approximation is used to solve the flow in the porous region. The Navier–Stokes
equation is used to describe the flow in the clear flow region. The dependence of the average Nusselt number on several flow
and geometric parameters is investigated. These include: convective parameter, λ, Darcy number, Da, thermal conductivity ratio,
K
r, and porous-insert thickness to gap ratio (H/D). It is found that, in general, the heat transfer enhances by the presence of porous layers of high thermal conductivity
ratios. It is also found that there is a critical thermal conductivity ratio on which if the values of Kr are higher than
the critical value the average Nusselt number starts to decrease. Also, it found that at low thermal conductivity ratio (K
r ≈ 1) and for all values of λ the porous material acts as thermal insulation. 相似文献
9.
This article presents a mathematical model describing flow of two fluid phases in a heterogeneous porous medium. The medium
contains disconnected inclusions embedded in the background material. The background material is characterized by higher value
of the non-wetting-phase entry pressure than the inclusions, which causes non-standard behavior of the medium at the macroscopic
scale. During the displacement of the non-wetting fluid by the wetting one, some portions of the non-wetting fluid become
trapped in the inclusions. On the other hand, if the medium is initially saturated with the wetting phase, it starts to drain
only after the capillary pressure exceeds the entry pressure of the background material. These effects cannot be represented
by standard upscaling approaches based on the assumption of local equilibrium of the capillary pressure. We propose a relevant
modification of the upscaled model obtained by asymptotic homogenization. The modification concerns the form of flow equations
and the calculation of the effective hydraulic functions. This approach is illustrated with two numerical examples concerning
oil–water and CO2–brine flow, respectively. 相似文献
10.
Finite Element-Based Characterization of Pore-Scale Geometry and Its Impact on Fluid Flow 总被引:1,自引:0,他引:1
We present a finite element (FEM) simulation method for pore geometry fluid flow. Within the pore space, we solve the single-phase
Reynold’s lubrication equation—a simplified form of the incompressible Navier–Stokes equation yielding the velocity field
in a two-step solution approach. (1) Laplace’s equation is solved with homogeneous boundary conditions and a right-hand source
term, (2) pore pressure is computed, and the velocity field obtained for no slip conditions at the grain boundaries. From
the computed velocity field, we estimate the effective permeability of porous media samples characterized by section micrographs
or micro-CT scans. This two-step process is much simpler than solving the full Navier–Stokes equation and, therefore, provides
the opportunity to study pore geometries with hundreds of thousands of pores in a computationally more cost effective manner
than solving the full Navier–Stokes’ equation. Given the realistic laminar flow field, dispersion in the medium can also be
estimated. Our numerical model is verified with an analytical solution and validated on two 2D micro-CT scans from samples,
the permeabilities, and porosities of which were pre-determined in laboratory experiments. Comparisons were also made with
published experimental, approximate, and exact permeability data. With the future aim to simulate multiphase flow within the
pore space, we also compute the radii and derive capillary pressure from the Young–Laplace’s equation. This permits the determination
of model parameters for the classical Brooks–Corey and van-Genuchten models, so that relative permeabilities can be estimated. 相似文献
11.
J. Prathap Kumar J. C. Umavathi I. Pop Basavaraj M. Biradar 《Transport in Porous Media》2009,80(1):117-135
An analysis of fully developed combined free and forced convective flow in a fluid saturated porous medium channel bounded
by two vertical parallel plates is presented. The flow is modeled using Brinkman equation model. The viscous and Darcy dissipation
terms are also included in the energy equation. Three types of thermal boundary conditions such as isothermal–isothermal,
isoflux–isothermal, and isothermal–isoflux for the left–right walls of the channel are considered. Analytical solutions for
the governing ordinary differential equations are obtained by perturbation series method. In addition, closed form expressions
for the Nusselt number at both the left and right channel walls are derived. Results have been presented for a wide range
of governing parameters such as porous parameter, ratio of Grashof number and Reynolds number, viscosity ratio, width ratio,
and conductivity ratio on velocity, and temperature fields. It is found that the presence of porous matrix in one of the region
reduces the velocity and temperature. 相似文献
12.
The interacting capillary bundle model proposed by Dong et al. [Dong, M., Dullien, F.A.L., Zhou, J.: Trans. Porous Media 31, 213–237 (1998); Dong, M., Dullien, F.A.L., Dai, L., Li, D.: Trans. Porous Media 59, 1–18 (2005); Dong, M., Dullien, F.A.L., Dai, L., Li, D.: Trans. Porous Media 63, 289–304 (2006)] has simulated correctly various aspects of immiscible displacement in porous media, such as oil production
histories at different viscosity ratios, the effects of water injection rate and of the oil–water viscosity ratio on the shape
of the displacement front and the independence of relative permeabilities of the viscosity ratio. In the interacting capillary
bundle model pressure equilibrium was assumed at any distance x measured along the bundle. Interaction between the capillaries also results in transfer of fluids across the capillaries.
In the first part of this paper the process of fluid transfer between two capillaries is analysed and an algebraic expression
for this flow is derived. Consistency with the assumption of pressure equilibration requires that all transfer must take place
at the positions of the oil/water menisci in the tubes without any pressure drop. It is shown that fluid transfer between
the tubes has no effect on the predictions obtained with the model. In the second part of the paper the interacting tube bundle
model is made more realistic by assuming fluid transfer between the tubes all along the single phase flow regions across a
uniform resistance, resulting in pressure differences throughout the single phase regions between the fluids present in the
different tubes. The results of numerical simulations obtained with this improved interacting capillary bundle model show
only small differences in the positions of the displacement front as compared with the predictions of the idealized model. 相似文献
13.
The Characterization of the effects of surface wettability and geometry on pressure drop of slug flow in isothermal horizontal
microchannels is investigated for circular and square channels with hydraulic diameter (D
h
) of 700 μm. Flow visualization is employed to characterize the bubble in slug flow established in microchannels of various
surface wettabilities. Pressure drop increases with decrease in surface wettability, while the channel geometry influences
slug frequency. It is observed that the gas–liquid contact line in advancing and receding interfaces of bubble change with
surface wettability in slug flows. Flow resistance, where capillary force is important, is estimated using Laplace–Young equation
considering the change of dynamic contact angles of bubble. The experimental study also demonstrates that the liquid film
presence elucidates the pressure drop variation of slug flows at various surface wettabilities due to diminishing capillary
effect. 相似文献
14.
Marc Dees Marc Mangnus Nicolaas Hermans Wouter Thaens Anne-Sophie Hanot Peter Van Puyvelde 《Rheologica Acta》2011,50(2):117-124
In this paper, the importance of a pressure correction of viscosity data obtained in capillary melt rheology is demonstrated.
A linear polycarbonate has been chosen as a highly pressure-sensitive material for which data obtained by rotational rheometry
does not overlap with capillary data. This apparent problem with the Cox–Merz relation is attributed to the existence of a
mean pressure inside the capillary which is significantly different from atmospheric conditions. Different methods to determine
the pressure coefficient of polycarbonate have been evaluated based on experiments performed with a capillary rheometer equipped
with a pressure chamber. It is demonstrated that the pressure coefficient obtained at constant shear stress and the pressure
coefficient obtained by the superposition method represent accurate pressure coefficient values. Two approaches are proposed
to correct the original capillary data. In the direct methodology, the pressure coefficient is used to rescale the mean pressure
inside the capillary to atmospheric conditions. The indirect approach consists of first constructing a mastercurve at a certain
reference pressure using capillary data obtained with a pressure chamber. The resulting mastercurve can then be rescaled to
atmospheric conditions. It is shown that both methods lead to viscosity curves on which both rotational and capillary data
overlap, hence confirming the Cox–Merz relationship for polycarbonate. The indirect method is proven to be advantageous since
it opens the possibility to significantly extend the shear rate window in which viscosities can be measured. 相似文献
15.
Two-phase flow through a medium with two porosities in which the absolute permeabilities and the capillary pressure functions
of the components differ by an order of magnitude is investigated. A classification and diagram of the elementary flows are
proposed at the single cell level. An averaged model is developed for a single class of systems in which source-type capillary-dispersion
flow predominates in the blocks. This model contains a nonlinear kinetic relation between the average values of the capillary
pressure functions. An expansion of the effective phase permeability tensor allowing it to be calculated efficiently is proposed.
The capillary relaxation time is explicitly determined. Examples of calculations of the averaged phase permeability tensor
and the capillary relaxation time are given.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 93–103, May–June, 1998.
The work was carried out with the support from the Russian Foundation for Basic Research (project No. 95-01-01179a). 相似文献
16.
The linear stability theory for the Horton–Rogers–Lapwood problem is extended to the case where the porous medium is saturated
by a nanofluid with thermal conductivity and viscosity dependent on the nanoparticle volume fraction. The effects of Brownian
motion and thermophoresis are considered. In conjunction with the Brownian motion, the nanoparticle fraction becomes stratified,
and hence the viscosity and the conductivity are stratified. The nanofluid is assumed to be dilute and this enables the porous
medium to be treated as a weakly heterogeneous medium with variation, in the vertical direction, of conductivity and viscosity.
In turn this allows an approximate analytical solution to be obtained. 相似文献
17.
Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis 总被引:1,自引:0,他引:1
Gaiping Zhao Jie Wu Shixiong Xu M. W. Collins Quan Long Carola S. König Yuping Jiang Jian Wang A. R. Padhani 《Acta Mechanica Sinica》2007,23(5):477-483
A coupled intravascular–transvascular–interstitial fluid flow model is developed to study the distributions of blood flow
and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network. This is generated
from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels. Blood flow through
the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille’s law and
Darcy’s law, respectively, transvascular flow is described by Starling’s law; effects of the vascular permeability and the
interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial
hypertension and low convection on the inside of the tumor, which are consistent with physiological observed facts. These
results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.
The project supported by the National Natural Science Foundation of China (10372026). 相似文献
18.
O. V. Voinov 《Journal of Applied Mechanics and Technical Physics》2007,48(3):385-392
The motion of thin films of a viscous incompressible liquid in a gas under the action of capillary forces is studied. The
surface tension depends on the surfactant concentration, and the liquid is nonvolatile. The motion is described by the well-known
model of quasi-steady-state viscous film flow. The linear-wave solutions are compared with the solution using the Navier-Stokes
equations. Situations are studied where a solution close to the inviscid two-dimensional solutions exists and in the case
of long wavelength, the occurrence of sound waves in the film due to the Gibbs surface elasticity is possible. The behavior
of the exact solutions near the region of applicability of asymptotic equations is studied, and nonmonotonic dependences of
the wave characteristics on wavenumber are obtained.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 3, pp. 103–111, May–June, 2007. 相似文献
19.
Although, the effects of ultrasonic irradiation on multiphase flow through porous media have been studied in the past few
decades, the physics of the acoustic interaction between fluid and rock is not yet well understood. Various mechanisms may
be responsible for enhancing the flow of oil through porous media in the presence of an acoustic field. Capillary related
mechanisms are peristaltic transport due to mechanical deformation of the pore walls, reduction of capillary forces due to
the destruction of surface films generated across pore boundaries, coalescence of oil drops due to Bjerknes forces, oscillation
and excitation of capillary trapped oil drops, forces generated by cavitating bubbles, and sonocapillary effects. Insight
into the physical principles governing the mobilization of oil by ultrasonic waves is vital for developing and implementing
novel techniques of oil extraction. This paper aims at identifying and analyzing the influence of high-frequency, high-intensity
ultrasonic radiation on capillary imbibition. Laboratory experiments were performed using cylindrical Berea sandstone and
Indiana limestone samples with all sides (quasi-co-current imbibition), and only one side (counter-current imbibition) contacting
with the aqueous phase. The oil saturated cores were placed in an ultrasonic bath, and brought into contact with the aqueous
phase. The recovery rate due to capillary imbibition was monitored against time. Air–water, mineral oil–brine, mineral oil–surfactant
solution and mineral oil-polymer solution experiments were run each exploring a separate physical process governing acoustic
stimulation. Water–air imbibition tests isolate the effect of ultrasound on wettability, capillarity and density, while oil–brine
imbibition experiments help outline the ultrasonic effect on viscosity and interfacial interaction between oil, rock and aqueous
phase. We find that ultrasonic irradiation enhances capillary imbibition recovery of oil for various fluid pairs, and that
such process is dependent on the interfacial tension and density of the fluids. Although more evidence is needed, some runs
hint that wettability was not altered substantially under ultrasound. Preliminary analysis of the imbibition recoveries also
suggests that ultrasound enhances surfactant solubility and reduce surfactant adsorption onto the rock matrix. Additionally,
counter-current experiments involving kerosene and brine in epoxy coated Berea sandstone showed a dramatic decline in recovery.
Therefore, the effectiveness of any ultrasonic application may strongly depend on the nature of interaction type, i.e., co-
or counter-current flow. A modified form of an exponential model was employed to fit the recovery curves in an attempt to
quantify the factors causing the incremental recovery by ultrasonic waves for different fluid pairs and rock types. 相似文献
20.
Field amplified sample stacking (FASS) is used to increase sample concentrations in electrokinetic flows. The technique uses
conductivity gradients to establish a non-uniform electric field that accumulates ions within a conductivity gradient, and
can be readily integrated with capillary electrophoresis. Conductivity gradients also cause gradients in near-wall electroosmotic
flow velocities. These velocity gradients generate internal pressure gradients that drive secondary, dispersive flows. This
dispersion leads to a significant reduction in the efficiency of sample stacking. This paper presents an experimental investigation
of internally generated pressure gradients in FASS using micron-resolution particle image velocimetry (μPIV). We measure velocity
fields of particles seeded into an electrokinetic FASS flow field in a glass microchannel with a single buffer–buffer interface. μPIV
allows for the direct quantification of local, instantaneous pressure gradients by analyzing the curvature of velocity profiles.
Measurements show internally generated pressure-driven velocities on the order of 1mm/s for a typical applied electric field
of 100 V/cm and a conductivity ratio of 10. A one-dimensional (1D) analytical model for the temporal development of the internal
pressure gradient generation is proposed which is useful in estimating general trends in flow dynamics.
相似文献
Juan G. SantiagoEmail: |