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1.
Multiphase fluid dynamics and transport processes of low capillary number cavitating flows 总被引:1,自引:0,他引:1
Wei Shyy 《Acta Mechanica Sinica》2009,25(2):161-172
To better understand the multiphase fluid dynamics and associated transport processes of cavitating flows at the capillary number of 0.74 and 0.54, and to validate the numerical results, a combined computational and experimental investigation of flows around a hydrofoil is studied based on flow visualizations and time-resolved interface movement. The computational model is based on a modified RNG k-ε model as turbulence closure, along with a vapor-liquid mass transfer model for treating the cavitation process. Overall, favorable agreement between the numerical and experimental results is observed. It is shown that the cavi- tation structure depends on the interaction of the water-vapor mixture and the vapor among the whole cavitation stage, the interface between the vapor and the two-phase mixture exhibits substantial unsteadiness. And, the adverse motion of the interface relates to pressure and velocity fluctuations inside the cavity. In particular, the velocity in the vapor region is lower than that in the two-phase region. 相似文献
2.
3.
A. A. Chensokov 《Journal of Applied Mechanics and Technical Physics》1998,39(4):513-523
Quasi-linear integrodifferential equations that describe vortex flows of an ideal incomparessible liquid in a narrow curved
channel in the Eulerian-Lagrangian coordinate system are considered. The necessary and sufficient conditions for hyperbolicity
of the system of equations of motion are obtained for flows with a monotonic velocity depth profile. The propagation velocities
of the characteristics and the characteristic form of the system are calculated. A particular solution is given in which the
system of integrodifferential equations changes type with time. The solution of the Cauchy problem is given for linearized
equations. An example of initial data for which the Cauchy problem is ill-posed is constructed.
Novosibirsk State University, Novosibirsk 630090. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39,
No. 4, pp. 38–49, July–August, 1998. 相似文献
4.
P. K. Volkov 《Fluid Dynamics》1994,29(4):500-507
The steady rise of a vapor bubble in a liquid moving in a vertical tube is modeled by means of the Navier-Stokes equations.
The shape of the vapor bubble (drop) and the structure of the flow are determined by numerically solving the equations inside
and outside the drop. The calculations are made on the interval of intermediate values of the dimensionless parameters and
describe the transition to piston-type motion. The solutions obtained are compared with the existing experimental and approximate
data for creeping flows.
Novosibirsk. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 76–86, July–August,
1994. 相似文献
5.
The solidification of an infinitely long square prism was analyzed numerically. A front fixing technique along with an algebraic
grid generation scheme was used, where the finite difference form of the energy equation is solved for the temperature distribution
in the solid phase and the solid–liquid interface energy balance is integrated for the new position of the moving solidification
front. Results are given for the moving solidification boundary with a circular phase change interface. An algebraic grid
generation scheme was developed for two-dimensional domains, which generates grid points separated by equal distances in the
physical domain. The current scheme also allows the implementation of a finer grid structure at desired locations in the domain.
The method is based on fitting a constant arc length mesh in the two computational directions in the physical domain. The
resulting simultaneous, nonlinear algebraic equations for the grid locations are solved using the Newton-Raphson method for
a system of equations. The approach is used in a two-dimensional solidification problem, in which the liquid phase is initially
at the melting temperature, solved by using a front-fixing approach. The difference of the current study lies in the fact
that front fixing is applied to problems, where the solid–liquid interface is curved such that the position of the interface,
when expressed in terms of one of the coordinates is a double valued function. This requires a coordinate transformation in
both coordinate directions to transform the complex physical solidification domain to a Cartesian, square computational domain.
Due to the motion of the solid–liquid interface in time, the computational grid structure is regenerated at every time step. 相似文献
6.
A. A. Chesnokov V. Yu. Liapidevskii 《Journal of Applied Mechanics and Technical Physics》2009,50(2):220-228
This paper considers a nonlinear integrodifferential model constructed for the motion of an ideal incompressible fluid in
an open channel of variable section using the long-wave approximation. A characteristic equation for describing the perturbation
propagation velocity in the fluid is derived. Necessary and sufficient conditions of generalized hyperbolicity for the equations
of motion are formulated, and the characteristic form of the system is calculated. In the case of a channel of constant width,
the model reduces to the Riemann integral invariants which are conserved along the characteristics. It is found that, during
the evolution of the flow, the type of the equations of motion can change, which corresponds to long-wave instability for
a certain velocity distribution along the channel width.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 61–71, March–April, 2009. 相似文献
7.
V. M. Teshukov 《Journal of Applied Mechanics and Technical Physics》2007,48(3):303-309
The classical shallow-water equations describing the propagation of long waves in flow without a shear of the horizontal velocity
along the vertical coincide with the equations describing the isentropic motion of a polytropic gas for a polytropic exponent
γ = 2 (in the theory of fluid wave motion, this fact is called the gas-dynamic analogy). A new mathematical model of long-wave
theory is derived that describes shear free-boundary fluid flows. It is shown that in the case of one-dimensional motion,
the equations of the new model coincide with the equations describing nonisentropic gas motion with a special choice of the
equation of state, and in the multidimensional case, the new system of long-wave equations differs significantly from the
gas motion model. In the general case, it is established that the system of equations derived is a hyperbolic system. The
velocities of propagation of wave perturbations are found.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 3, pp. 8–15, May–June, 2007. 相似文献
8.
The boundary-value problem of unsteady vortex flow of a viscous incompressible fluid in a cylindrical vessel with radial ribs
rotating at a variable angular velocity is solved using a finite-difference method. The results of the solution are used to
calculate the motion of a system of a solid body and a cavity filled with a liquid. The results are compared with available
experimental data.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 135–139, March–April, 2007. 相似文献
9.
D. V. Sadin 《Fluid Dynamics》1994,29(1):156-158
The unsteady filtering flow of a gas described by the equations of motion proposed by Khristianovich in [1] is investigated.
It is shown that for the gas flow in the pores a critical regime can develop when the reduced velocity (an analog of the Mach
number in gas dynamics) is less than unity. The reduced velocity is the ratio of the flow velocity to the velocity of propagation
of small filtering perturbations at a given point of the flow.
St Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 201–203, January–February,
1994. 相似文献
10.
The process of contact melting of the solid phase change material (PCM) around a hot sphere, which is driven by the temperature
difference between the PCM and the sphere, is analyzed in this paper. Considering the difference of the normal angle between
the sphere surface and the solid–liquid interface of the melting PCM, the fundamental equations of the melting process are
derived with the film theory. The new film thickness and pressure distribution inside the liquid film and the variation law
of the normal angle of the solid–liquid interface and the melting velocity of the sphere are also obtained. It is found that
(1) while normal angle at sphere surface φ is within a certain value φ0, which is related to Ste number and the outside force F, it has no obvious effect on the pressure distribution inside the liquid film and the numerical results by the present model
are in accordance with the analytical results in the published literature, (2) the film thickness at φ = ±90° is constringent
to a certain value and not the infinity, (3) the analytical results can be employed approximately to analyze the contact melting
process except for the film thickness at φ = ±90°. 相似文献
11.
12.
A. A. Chesnokov 《Journal of Applied Mechanics and Technical Physics》2008,49(5):737-748
This paper considers nonlinear equations describing the propagation of long waves in two-dimensional shear flow of a heavy
ideal incompressible fluid with a free boundary. A nine-dimensional group of transformations admitted by the equations of
motion is found by symmetry methods. Two-dimensional subgroups are used to find simpler integrodifferential submodels which
define classes of exact solutions, some of which are integrated. New steady-state and unsteady rotationally symmetric solutions
with a nontrivial velocity distribution along the depth are obtained.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 5, pp. 41–54, September–October, 2008. 相似文献
13.
Microwave heating of a liquid and large spherical particles that it carries while continuously flowing in a circular applicator
pipe is investigated. A three-dimensional model that includes coupled Maxwell, continuity, Navier–Stokes, and energy equations
is developed to describe transient temperature, electromagnetic, and fluid velocity fields. The hydrodynamic interaction between
the solid particles and the carrier liquid is simulated by the force-coupling method (FCM). Computational results are presented
for the microwave power absorption, temperature distribution inside the liquid and the particles, as well as the velocity
distribution in the applicator pipe and trajectories of particles. The effect of the time interval between consecutive injections
of two groups of particles on power absorption in particles is studied. The influence of the position of the applicator pipe
in the microwave cavity on the power absorption and temperature distribution inside the liquid and the particles is investigated
as well. 相似文献
14.
Pasqua D'Ambra 《Continuum Mechanics and Thermodynamics》1997,9(2):97-114
In this work we present some results of the numerical simulation of the growth of a crystal from its melt, taking into account
faceting. The simulation is based on a numerical solution of a three–dimensional generalized Stefan problem. That problem
arises from a non–local thermomechanical theory applied to a continuous system with an interface and embodies ideas from the
dislocation theory of crystal growth. In the model, the crystal surface is an isotherm and the growth velocity of a crystal
face depends on the velocities of the other faces and on the whole crystal configuration as well as on the temperature gradient.
A front fixing formulation of the model is considered. This is a conservative form of the Isotherm Migration Method [6, 7,
8, 9, 10, 11] in spherical coordinates. The numerical solution is based on an explicit finite difference discretization of
the resulting non–linear equations. We develop a theoretical analysis of the interface equations that drive the crystal face
motion. Numerical results, showing evolution of complex crystals with configuration changing during the growth, are in accord
with experimental results. Furthermore, numerical experiments offer useful information on the influence of certain parameters
in the model on the growth process.
Received: March 21, 1996 相似文献
15.
B. P. Avksentyuk V. V. Ovchinnikov 《Journal of Applied Mechanics and Technical Physics》1999,40(6):1070-1076
A physical model for explosive boiling of drops is presented. Loss of stability of the liquid-vapor interface results in occurrence
of evaporation fronts. Their propagation in a metastable liquid is determined by the vapor recoil momentum. Detachment of
drops from the interface is due to thermocapillary forces. The validity of the model is supported by comparison of calculations
with experimental data.
Kutateladze Institute of Thermal Physics, Siberian Division, Russian Academy of Science, Novosibirsk 630090. Translated from
Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 6, pp. 83–91, November–December, 1999. 相似文献
16.
V. D. Kubenko 《International Applied Mechanics》2006,42(6):636-654
An approach is developed to the investigation of the shock interaction between a long thin cylindrical body and a cylindrical
cavity in an infinite compressible perfect liquid. This process accompanies the supercavitation of the body. Three typical
cases of cross-sectional dimensions of the body and the cavity are examined. For each case, a mixed nonstationary boundary-value
problem with an unknown moving boundary is formulated. The unknown quantities are expanded into Fourier series. An auxiliary
problem is solved using the Laplace transform to establish the relationship between the pressure and the velocity on the cavity
surface. As a result, the problem is reduced to an infinite system of Volterra equations of the second kind solved simultaneously
with the equation of transverse motion and the equation of the contact boundary. An asymptotic solution valid at the initial
stage of interaction is obtained for all the three cases, and a numerical solution is found for the most typical case
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 6, pp. 32–53, June 2006. 相似文献
17.
V. A. Petushkov A. N. Mel'sitov 《Journal of Applied Mechanics and Technical Physics》2006,47(1):116-126
The propagation of shock waves in a system consisting of a deformable medium with damage and a two-phase liquid with gas or
vapor bubbles are studied. The nonlinear interaction of the media are modeled taking into account phase transformations in
the liquid and the damage kinetics of the deformable medium.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 1, pp. 139–152, January–February, 2006. 相似文献
18.
We investigate the transient film boiling in the vicinity of a stagnation point on the frontal surface of a very hot blunt
body which moves with a constant velocity in an incompressible viscous fluid in the presence of a vapor layer near the body
surface. Within the unsteady two-phase boundary layer approximation, the equations of motion of the liquid and vapor phases
are formulatedwith account of the conservation of mass, momentum, and energy on the a priori unknown phase interface. In the
vicinity of the stagnation point on the body surface, the solution of the boundary layer equations is sought in the form of
series in the longitudinal coordinate. For the leading terms of the series, a parabolic system of partial differential equations
is obtained, which is solved numerically. The similarity parameters controlling the film boiling process are determined. On
the basis of parametric numerical calculations, the dynamics of the vapor layer are investigated for the case of a plane hot
body moving in water with the room pressure and temperature. In the space of governing parameters, the limits of the existence
of steady and unsteady film boiling regimes are found. 相似文献
19.
Stefan Mählmann Demetrios T. Papageorgiou 《Theoretical and Computational Fluid Dynamics》2009,23(5):375-399
The effect of an electric field on the buoyancy-driven motion of a two-dimensional gas bubble rising through a quiescent liquid
is studied computationally. The dynamics of the bubble is simulated numerically by tracking the gas–liquid interface when
an electrostatic field is generated in the vertical gap of the rectangular enclosure. The two phases of the system are assumed
to be perfect dielectrics with constant but different permittivities, and in the absence of impressed charges, there is no
free charge in the fluid bulk regions or at the interface. Electric stresses are supported at the bubble interface but absent
in the bulk and one of the objectives of our computations is to quantify the effect of these Maxwell stresses on the overall
bubble dynamics. The numerical algorithm to solve the free-boundary problem relies on the level-set technique coupled with
a finite-volume discretization of the Navier–Stokes equations. The sharp interface is numerically approximated by a finite-thickness
transition zone over which the material properties vary smoothly, and surface tension and electric field effects are accounted
for by employing a continuous surface force approach. A multi-grid solver is applied to the Poisson equation describing the
pressure field and the Laplace equation governing the electric field potential. Computational results are presented that address
the combined effects of viscosity, surface tension, and electric fields on the dynamics of the bubble motion as a function
of the Reynolds number, gravitational Bond number, electric Bond number, density ratio, and viscosity ratio. It is established
through extensive computations that the presence of the electric field can have an important effect on the dynamics. We present
results that show a substantial increase in the bubble’s rise velocity in the electrified system as compared with the corresponding
non-electrified one. In addition, for the electrified system, the bubble shape deformations and oscillations are smaller,
and there is a reduction in the propensity of the bubble to break up through increasingly larger oscillations. 相似文献