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1.
We study locally mass conservative approximations of coupled Darcy and Stokes flows on polygonal and polyhedral meshes. The discontinuous Galerkin (DG) finite element method is used in the Stokes region and the mimetic finite difference method is used in the Darcy region. DG finite element spaces are defined on polygonal and polyhedral grids by introducing lifting operators mapping mimetic degrees of freedom to functional spaces. Optimal convergence estimates for the numerical scheme are derived. Results from computational experiments supporting the theory are presented. 相似文献
2.
An operator splitting approach for the interaction between a fluid and a multilayered poroelastic structure
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Martina Bukač Ivan Yotov Paolo Zunino 《Numerical Methods for Partial Differential Equations》2015,31(4):1054-1100
We develop a loosely coupled fluid‐structure interaction finite element solver based on the Lie operator splitting scheme. The scheme is applied to the interaction between an incompressible, viscous, Newtonian fluid, and a multilayered structure, which consists of a thin elastic layer and a thick poroelastic material. The thin layer is modeled using the linearly elastic Koiter membrane model, while the thick poroelastic layer is modeled as a Biot system. We prove a conditional stability of the scheme and derive error estimates. Theoretical results are supported with numerical examples. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 1054–1100, 2015 相似文献
3.
Johann Davidov Gueo Grantcharov Oleg Mushkarov Miroslav Yotov 《Communications in Mathematical Physics》2011,304(1):49-68
In this paper we consider pseudo-bihermitian structures – pairs of complex structures compatible with a pseudo-Riemannian metric. We establish relations of these structures with generalized (pseudo-) Kähler geometry and holomorphic Poisson structures similar to that in the positive definite case. We provide a list of compact complex surfaces which could admit pseudo-bihermitian structures and give examples of such structures on some of them. We also consider a naturally defined null plane distribution on a generalized pseudo-Kähler 4-manifold and show that under a mild restriction it determines an Engel structure. 相似文献
4.
We develop a local flux mimetic finite difference method for second order elliptic equations with full tensor coefficients
on polyhedral meshes. To approximate the velocity (vector variable), the method uses two degrees of freedom per element edge
in two dimensions and n degrees of freedom per n-gonal mesh face in three dimensions. To approximate the pressure (scalar variable), the method uses one degree of freedom
per element. A specially chosen quadrature rule for the L
2-product of vector-functions allows for a local flux elimination and reduction of the method to a cell-centered finite difference
scheme for the pressure unknowns. Under certain assumptions, first-order convergence is proved for both variables and second-order
convergence is proved for the pressure. The assumptions are verified on simplicial meshes for a particular quadrature rule
that leads to a symmetric method. For general polyhedral meshes, non-symmetric methods are constructed based on quadrature
rules that are shown to satisfy some of the assumptions. Numerical results confirm the theory. 相似文献
5.
Marko Kirilov Galin Petrov Nikolaj Tyutyulkov Yoto Yotov 《Monatshefte für Chemie / Chemical Monthly》1975,106(6):1533-1541
The applicability of the principle of linear free energies to the tautomerism of dialkyl esters of 1-cyano-2-oxo-alkanephosphonic acids is studied. Correlations between the tautomeric equilibrium constants andTaft's inductive constants, as well asKabachnik's σ ? constants of the substituents in RO-groups at the phosphorus atom and those at the carbonyl group in some series of compounds of this type are found. The dominating inductive influence of the R-substituents on the position of tautomeric equilibrium in these compounds is proved also by model quantum chemical investigation of the effects of conjugation in the corresponding tautomeric forms byHückel's LCAO—MO-method. 相似文献
6.
We investigate mortar multiscale numerical methods for coupled Stokes and Darcy flows with the Beavers–Joseph–Saffman interface condition. The domain is decomposed into a series of subdomains (coarse grid) of either Stokes or Darcy type. The subdomains are discretized by appropriate Stokes or Darcy finite elements. The solution is resolved locally (in each coarse element) on a fine scale, allowing for non-matching grids across subdomain interfaces. Coarse scale mortar finite elements are introduced on the interfaces to approximate the normal stress and impose weakly continuity of the normal velocity. Stability and a priori error estimates in terms of the fine subdomain scale $h$ and the coarse mortar scale $H$ are established for fairly general grid configurations, assuming that the mortar space satisfies a certain inf-sup condition. Several examples of such spaces in two and three dimensions are given. Numerical experiments are presented in confirmation of the theory. 相似文献
7.
In this paper, we develop a new mixed finite element method for elliptic problems on general quadrilateral and hexahedral
grids that reduces to a cell-centered finite difference scheme. A special non-symmetric quadrature rule is employed that yields
a positive definite cell-centered system for the pressure by eliminating local velocities. The method is shown to be accurate
on highly distorted rough quadrilateral and hexahedral grids, including hexahedra with non-planar faces. Theoretical and numerical
results indicate first-order convergence for the pressure and face fluxes. 相似文献
8.
N. Minkov S. B. Drenska P. Yotov D. Bonatsos W. Scheid 《Physics of Atomic Nuclei》2007,70(8):1470-1475
We apply the collective axial quadrupole—octupole Hamiltonian to describe the rotation—vibration motion of odd nuclei with
Coriolis coupling between the even-even core and the unpaired nucleon.We consider that the core oscillates coherently with
respect to the quadrupole and octupole axialdeformation variables. The coupling between the core and the unpaired nucleon
provides a split paritydoublet structure of the spectrum. The formalism successfully reproduces the parity-doublet splitting
in a wide range of odd-A nuclei. It provides model estimations for the third angular-momentum projection K on the intrinsic symmetry axis and the related intrinsic nuclear structure.
The text was submitted by the authors in English. 相似文献
9.
We study the problem of existence of geometric structures on compact complex surfaces that are related to split quaternions. These structures, called para-hypercomplex, para-hyperhermitian and para-hyperkähler, are analogs of the hypercomplex, hyperhermitian and hyperkähler structures in the definite case. We show that a compact 4-manifold carries a para-hyperkähler structure iff it has a metric of split signature together with two parallel, null, orthogonal, pointwise linearly independent vector fields. Every compact complex surface admitting a para-hyperhermitian structure has vanishing first Chern class and we show that, unlike the definite case, many of these surfaces carry infinite-dimensional families of such structures. We provide also compact examples of complex surfaces with para-hyperhermitian structures which are not locally conformally para-hyperkähler. Finally, we discuss the problem of non-existence of para-hyperhermitian structures on Inoue surfaces of type S0 and provide a list of compact complex surfaces which could carry para-hypercomplex structures. 相似文献
10.
Anton Kapustin Ludmil Katzarkov Dmitri Orlov Mirroslav Yotov 《Central European Journal of Mathematics》2009,7(4):571-605
In this paper we outline the foundations of Homological Mirror Symmetry for manifolds of general type. Both Physics and Categorical
prospectives are considered. 相似文献