Lowest Equal-order Finite Element Research Articles

Stabilized multiphysics finite element method with Crank–Nicolson scheme for a poroelasticity model

In the paper, we propose a stabilized multiphysics finite element method with Crank–Nicolson scheme for a poroelasticity model. The method can eliminate the locking phenomenon and reveal the multi‐physical process. The lowest equal order finite element pair is used to reduce the computational cost. Furthermore, the method needs no constraint condition Δt = O(h2) and achieves optimal convergent order. Numerical tests are provided to illustrate the optimal accuracy and good performance in eliminating locking phenomenon of the method.

SUPG Approximation for the Oseen Viscoelastic Fluid Flow with Stabilized Lowest-Equal Order Mixed Finite Element Method

In this article, a stabilized mixed finite element (FE) method for the Oseen viscoelastic fluid flow (OVFF) obeying an Oldroyd-B type constitutive law is proposed and investigated by using the Streamline Upwind Petrov–Galerkin (SUPG) method. To find the approximate solution of velocity, pressure and stress tensor, we choose lowest-equal order FE triples P 1 - P 1 - P 1 , respectively. However, it is well known that these elements do not fulfill the i n f - s u p condition. Due to the violation of the main stability condition for mixed FE method, the system becomes unstable. To overcome this difficulty, a standard stabilization term is added in finite element variational formulation. The technique is applied herein possesses attractive features, such as parameter-free, flexible in computation and does not require any higher-order derivatives. The stability analysis and optimal error estimates are obtained. Three benchmark numerical tests are carried out to assess the stability and accuracy of the stabilized lowest-equal order feature of the OVFF.

Stabilized lowest equal-order mixed finite element method for the Oseen viscoelastic fluid flow

In this paper, we present a stabilized lowest equal-order mixed finite element (FE) method for the Oseen viscoelastic fluid flow obeying an Oldroyd-B type constitutive law. To approximate the velocity, pressure, and stress tensor, we choose lowest equal-order FE triples p1-p1-p1_{mathrm{dg}} respectively. It is well known that these elements don’t satisfy the inf–sup (or LBB) condition. Owing to the violation of the essential stability condition, the system became unstable. To overcome this difficulty, a standard pressure stabilization term is added to the discrete variational formulation, which ensures the well-posedness of the FE scheme. The existences and uniqueness of the FE scheme are derived. The desired optimal error bound is obtained. Three numerical experiments are executed to illustrate the validity and efficiency of the numerical method. The stabilized method provides attractive computational advantages, such as simpler data structures, parameter-free, no calculations of higher-order derivatives, and fast solver in simulations.

Adaptive stabilized finite volume method and convergence analysis for the Oseen equations

In this paper, based on the pressure project method, we consider an adaptive stabilized finite volume method for the Oseen equations with the lowest equal order finite element pair. Firstly, we develop the discrete forms in both finite element and finite volume methods, and establish the existence and uniqueness of numerical solutions by establishing the equivalence of linear terms in finite element and finite volume methods. Secondly, a residual type a posteriori error estimator is designed, and the computable global upper and local lower bounds between the exact solutions and the finite volume solutions are established. Thirdly, a discrete local lower bound between two successive finite volume solutions is obtained, convergence analysis of the adaptive stabilized finite volume method is also performed. Finally, some numerical results are presented to verify the performances of the developed error estimators and confirm the established theoretical findings.

A new multiscale finite element method for the 2D transient Navier–Stokes equations

ABSTRACTA new multiscale finite element method for the two-dimensional (2D) transient Navier–Stokes equations is proposed in this paper. This new method is based on multiscale enrichment with the lowest equal-order finite element pair . Under certain regularity assumptions, the optimal error estimates in -norm for velocity and -norm for pressure are obtained. Especially, via applying a new dual problem for the transient Navier–Stokes problem and some techniques in the proof process, we establish the convergence of the optimal order in -norm for the velocity. Finally, a numerical example confirms our theory analysis and validates the high effectiveness of this new method.

Analysis of a new stabilized finite volume element method based on multiscale enrichment for the Navier-Stokes problem

Purpose The purpose of this paper is to propose a new stabilized finite volume element method for the Navier-Stokes problem. Design/methodology/approach This new method is based on the multiscale enrichment and uses the lowest equal order finite element pairs P1/P1. Findings The stability and convergence of the optimal order in H1-norm for velocity and L2-norm for pressure are obtained. Originality/value Using a dual problem for the Navier-Stokes problem, the convergence of the optimal order in L2-norm for the velocity is obtained. Finally, numerical example confirms the theory analysis and validates the effectiveness of this new method.

Convergence analysis of a new multiscale finite element method for the stationary Navier–Stokes problem

In this paper, we propose a new multiscale finite element method for the stationary Navier–Stokes problem. This new method for the lowest equal order finite element pairs P1/P1 is based on the multiscale enrichment and derived from the Navier–Stokes problem itself. Therefore, the new multiscale finite element method better reflects the nature of the nonlinear problem. The well-posedness of this new discrete problem is proved under the standard assumption. Meanwhile, convergence of the optimal order in the H1-norm for the velocity and the L2-norm for the pressure is obtained. Especially, via applying a new dual problem and some techniques in the process for proof, we establish the convergence of the optimal order in the L2-norm for the velocity. Finally, numerical examples confirm our theory analysis and validate the effectiveness of this new method.

Two-Level Stabilized Finite Volume Methods for the Stationary Navier-Stokes Equations

AbstractIn this work, two-level stabilized finite volume formulations for the 2D steady Navier-Stokes equations are considered. These methods are based on the local Gauss integration technique and the lowest equal-order finite element pair. Moreover, the two-level stabilized finite volume methods involve solving one small Navier-Stokes problem on a coarse mesh with mesh size H, a large general Stokes problem for the Simple and Oseen two-level stabilized finite volume methods on the fine mesh with mesh size or a large general Stokes equations for the Newton two-level stabilized finite volume method on a fine mesh with mesh size . These methods we studied provide an approximate solution with the convergence rate of same order as the standard stabilized finite volume method, which involve solving one large nonlinear problem on a fine mesh with mesh size h. Hence, our methods can save a large amount of computational time.

Numerical Study on Several Stabilized Finite Element Methods for the Steady Incompressible Flow Problem with Damping

We discuss several stabilized finite element methods, which are penalty, regular, multiscale enrichment, and local Gauss integration method, for the steady incompressible flow problem with damping based on the lowest equal-order finite element space pair. Then we give the numerical comparisons between them in three numerical examples which show that the local Gauss integration method has good stability, efficiency, and accuracy properties and it is better than the others for the steady incompressible flow problem with damping on the whole. However, to our surprise, the regular method spends less CPU-time and has better accuracy properties by using Crout solver.

A STABILIZED CHARACTERISTIC FINITE VOLUME METHOD FOR TRANSIENT NAVIER-STOKES EQUATIONS

In this work, a stabilized characteristic finite volume method for the time-dependent Navier-Stokes equations is investigated based on the lowest equal-order finite element pair. The temporal differentiation and advection term are dealt with by characteristic scheme. Stability of the numerical solution is derived under some regularity assumptions. Optimal error estimates of the velocity and pressure are obtained by using the relationship between the finite volume and finite element methods.

Numerical Investigations on Several Stabilized Finite Element Methods for the Stokes Eigenvalue Problem

Several stabilized finite element methods for the Stokes eigenvalue problem based on the lowest equal‐order finite element pair are numerically investigated. They are penalty, regular, multiscale enrichment, and local Gauss integration method. Comparisons between them are carried out, which show that the local Gauss integration method has good stability, efficiency, and accuracy properties, and it is a favorite method among these methods for the Stokes eigenvalue problem.

Convergence and stability of a stabilized finite volume method for the stationary Navier-Stokes equations

In this paper, a new stabilized finite volume method is studied and developed for the stationary Navier-Stokes equations. This method is based on a local Gauss integration technique and uses the lowest equal order finite element pair P1–P1 (linear functions). Stability and convergence of the optimal order in the H1-norm for velocity and the L2-norm for pressure are obtained. A new duality for the Navier-Stokes equations is introduced to establish the convergence of the optimal order in the L2-norm for velocity. Moreover, superconvergence between the conforming mixed finite element solution and the finite volume solution using the same finite element pair is derived. Numerical results are shown to support the developed convergence theory.