共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper is concerned with the effects of numerical schemes on the simulation of dense gas-particle two-phase flows. The first-order upwind difference, the central difference, the second-order upwind difference, the central difference plus artificial dissipation, the deferred correction, the quadratic upstream interpolation (for convective kinematics) and the monotone upstream-centered schemes for conservation laws with different flux limiters were all accomplished to simulate the multi-phase flows. It was found that numerical schemes may significantly affect the solution accuracy and numerical convergence. The monotone upstream-centered schemes for conservation laws are the best choice of all, because they can effectively suppress the non-physical oscillations with the introduction of adaptive numerical dissipation into numerical solutions. 相似文献
2.
Ben Schweizer 《偏微分方程通讯》2013,38(5-6):887-901
We study the free boundary between a viscous and an inviscid fluid satisfying the Navier-Stokes and Euler equations respectively. Surface tension is incorporated. We read the equations as a free boundary problem for one viscous fluid with a nonlocal boundary force. We decompose the pressure distribution in the inviscid fluid into two contributions. A positivity result for the first, and a compactness property for the second contribution are dervied. We prove a short time existence theorem for the two-phase problem 相似文献
3.
This paper presents the coupled, and decoupled schemes for the naturally fractured reservoir consists of the triple-porosity medium. More specifically, the triple-porosity medium contains three contagious porous medium with more permeable macrofractures, less permeable microfractures, and matrix region which is often known as dual-fracture-matrix fluid flow model. Since the matrix has fluid communication with less permeable microfractures, and macrofratures are fed by the microfractures only, the global domain is divided into two subdomains by considering the traditional dual-porosity region and more permeable macrofractures region respectively. The flow and mass exchange between less permeable microfractures and more permeable macrofractures are modeled by two-fluid communication interface conditions while no-communication interface condition is imposed on between matrix and macrofractures region. The weak formulation and the well-posedness of the dual-fracture-matrix model are derived. Furthermore, coupled, implicit-explicit and data-passing partitioned schemes are proposed. The stability and the optimal convergence analysis are derived for both decoupled schemes. Five numerical examples are presented to illustrate the accuracy of the numerical methods and the applicability of the dual-fracture-matrix fluid flow model. Moreover, the parameter sensitivity analysis is performed in the fourth numerical example. 相似文献
4.
Andro Mikelic Laetitia Paoli 《Proceedings of the American Mathematical Society》1999,127(7):2019-2028
We consider the non-stationary incompressible Euler equations in a 2D porous medium. We suppose a periodic porous medium, with the period proportional to the characteristic pore size and with connected fluid part. The flow is subject to an external force, corresponding to an inflow. We start from an initial irrotational velocity and prove that the effective filtration velocity satisfies a transient filtration law. It has similarities with Darcy's law, but it now connects the time derivative of the filtration velocity with the pressure gradient. The viscosity does not appear in the filtration law any more and the permeability tensor is determined through auxiliary problems of decomposition type. Using the limit problem, we construct the correction for the fluid velocity and prove that -norm of the error is of order . Similarly, we estimate the difference between the fluid pressure and its correction in as .
5.
Antonio Scalia Mezhlum A. Sumbatyan Vitaly Popuzin 《Journal of Computational and Applied Mathematics》2013
The paper is concerned with the new iteration algorithm to solve boundary integral equations arising in boundary value problems of mathematical physics. The stability of the algorithm is demonstrated on the problem of a flow around bodies placed in the incompressible inviscid fluid. With a discrete numerical treatment, we approximate the exact matrix by a certain Töeplitz one and then apply a fast algorithm for this matrix, on each iteration step. We illustrate the convergence of this iteration scheme by a number of numerical examples, both for hard and soft boundary conditions. It appears that the method is highly efficient for hard boundaries, being much less efficient for soft boundaries. 相似文献
6.
The work presents two numerical solutions of compressible flows problems with high and very low Mach numbers. Both problems are numerically solved by finite volume method and the explicit MacCormack scheme using a grid of quadrilateral cells. Moved grid of quadrilateral cells is considered in the form of conservation laws using Arbitrary Lagrangian–Eulerian method. In the first case, inviscid transonic flow through cascade DCA 8% is presented and the numerical results are compared to experimental data. The second case, numerical solution of unsteady viscous flow in the channel for upstream Mach number M∞=0.012 and frequency of the wall motions 100 Hz is presented. The unsteady case can represent a simplified model of airflow coming from the trachea, through the glottal region with periodically vibrating vocal folds to the human vocal tract. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
The existence of a local (in time) classical solution of a free boundary problem for a two-layer inviscid incompressible fluid is shown. The method of successive approximations and the novel approach to Lagrangian coordinates of Solonnikov are used. 相似文献
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9.
We show that in general, the specification of a contact angle condition at the contact line in inviscid fluid motions is incompatible
with the classical field equations and boundary conditions generally applicable to them. The limited conditions under which
such a specification is permissible are derived; however, these include cases where the static meniscus is not flat. In view
of this situation, the status of the many ‘solutions’ in the literature which prescribe a contact angle in potential flows
comes into question. We suggest that these solutions which attempt to incorporate a phenomenological, but incompatible, condition
are in some, imprecise sense ‘weak-type solutions’; they satisfy or are likely to satisfy, at least in the limit, the governing
equations and boundary conditions everywhere except in the neighbourhood of the contact line. We discuss the implications
of the result for the analysis of inviscid flows with free surfaces. 相似文献
10.
Y. Charles Li 《Applied Mathematics Letters》2012,25(12):2188-2192
11.
Dynamic contact problems in elasticity are dealt with in the framework of nonlinear finite element methods. A new energymomentum conserving time-stepping scheme for the mortar contact formulation is presented. The proposed method relies on a reparametrization of the contact constraints in terms of specific invariants. For the time discretisation of the contact forces emanating from the mortar formulation the notion of a discrete gradient is applied. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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13.
This paper is devoted to analyze a splitting method for solving incompressible inviscid rotational flows. The problem is first recast into the velocity–vorticity–pressure formulation by introducing the additional vorticity variable, and then split into three consecutive subsystems. For each subsystem, the L2 least-squares finite element approach is applied to attain accurate numerical solutions. We show that for each time step this splitting least-squares approach exhibits an optimal rate of convergence in the H1 norm for velocity and pressure, and a suboptimal rate in the L2 norm for vorticity. A numerical example in two dimensions is presented, which confirms the theoretical error estimates. 相似文献
14.
Vladimir Scheffer 《Journal of Geometric Analysis》1993,3(4):343-401
There exists a nonzero weak solution to the Euler equations of time-dependent incompressible fluid flow in the plane such that this solution has compact support in space-time. 相似文献
15.
We study approximations by conforming methods of the solution to the variational inequality \({\langle \partial_t u,v-u\rangle + \psi(v) - \psi(u) \ge \langle f,v-u\rangle}\) , which arises in the context of inviscid incompressible Bingham type fluid flows and of the total variation flow problem. In the general context of a convex lower semi-continuous functional \({\psi}\) on a Hilbert space, we prove the convergence of time implicit space conforming approximations, without viscosity and for nonsmooth data. Then, we introduce a general class of total variation functionals \({\psi}\) , for which we can apply the regularization method. We consider the time implicit regularized, linearized or not, algorithms and prove their convergence for general total variation functionals. A comparison with an analytical solution concludes this study. 相似文献
16.
K. N. Venkatasiva Murthy 《Proceedings Mathematical Sciences》1980,89(2):103-112
The MHD Couette flow of a viscous stratified fluid of large electrical conductivity with suction and injection at the plane
boundaries is studied when the plane boundaries are maintained at different temperatures. The Oseen type governing equations
are formulated using the method suggested by Greenspan for stratified fluids. Introducing the similarity variables, the linearised
equations are solved to obtain the velocity and temperature distributions. The results show that the behaviour of velocity
and temperature in fluids of large conductivity is different from the behaviour of velocity and temperature for fluids of
finite conductivity. The effect of the magnetic field on the load capacity is investigated for the case when the width of
the channel is small. 相似文献
17.
Fast and simple approximation schemes for generalized flow 总被引:3,自引:0,他引:3
We present fast and simple fully polynomial-time approximation schemes (FPTAS) for generalized versions of maximum flow, multicommodity
flow, minimum cost maximum flow, and minimum cost multicommodity flow. We extend and refine fractional packing frameworks
introduced in FPTAS’s for traditional multicommodity flow and packing linear programs. Our FPTAS’s dominate the previous best
known complexity bounds for all of these problems, some by more than a factor of n
2, where n is the number of nodes. This is accomplished in part by introducing an efficient method of solving a sequence of
generalized shortest path problems. Our generalized multicommodity FPTAS’s are now as fast as the best non-generalized ones.
We believe our improvements make it practical to solve generalized multicommodity flow problems via combinatorial methods.
Received: June 3, 1999 / Accepted: May 22, 2001?Published online September 17, 2001 相似文献
18.
Yann Brenier 《Calculus of Variations and Partial Differential Equations》2013,47(1-2):55-64
We consider L2 minimizing geodesics along the group of volume preserving maps SDiff(D) of a given 3-dimensional domain D. The corresponding curves describe the motion of an ideal incompressible fluid inside D and are (formally) solutions of the Euler equations. It is known that there is a unique possible pressure gradient for these curves whenever their end points are fixed. In addition, this pressure field has a limited but unconditional (internal) regularity. The present paper completes these results by showing: (1) the uniqueness property can be viewed as an infinite dimensional phenomenon (related to the possibility of relaxing the corresponding minimization problem by convex optimization), which is false for finite dimensional configuration spaces such as O(3) for the motion of rigid bodies; (2) the unconditional partial regularity is necessarily limited. 相似文献
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20.
O. M. Belotserkovskii M. S. Belotserkovskaya V. V. Denisenko I. V. Eriklintsev S. A. Kozlov E. I. Oparina O. V. Troshkin S. V. Fortova 《Computational Mathematics and Mathematical Physics》2014,54(1):172-176
The evolution of an initial perturbation in an axisymmetric subsonic normal inviscid gas flow through a pipe is directly simulated. The basic (unperturbed) flow has a zero radial velocity component, while its axial velocity component (along the axis of symmetry) increases or decreases linearly with the radius. The perturbation is specified as a swirl (rotation about the axis) with a positive or negative velocity vanishing on the central axis and the lateral surface. Irrespective of its direction, the swirl gives rise to a steady-state vortex carried by the flow. It shape is spherical (contiguous to the rotation axis) or circular (sliding along the impermeable lateral surface). 相似文献