Abstract:The incompressible Stokes equations with prescribed normal stress (open) boundary conditions on part of the boundary are considered. It is shown that the standard pressure-correction method is not suitable for approximating the Stokes equations with open boundary conditions, whereas the rotational pressure-correction method yields reasonably good error estimates. These results appear to be the first ever published for splitting schemes with open boundary conditions. Numerical results in agreement with the erro… Show more
“…We shall demonstrate in the series of numerical experiments that the scheme retains second order accuracy if t varies smoothly. In the case of outflow boundary conditions, building a second order accurate stable pressure projection method is a well-known problem, see, e.g., [24,25]. It is not our intention to address this problem in the present paper.…”
Section: Numerical Time-integrationmentioning
confidence: 97%
“…It is not our intention to address this problem in the present paper. If one sets ν ∂ u n+1 ∂n Γ 2 = p n n in (10), then Guermond et al [24] proved that the splitting method is up to 3 2 order the accurate (the actual order depends on a certain regularity index). However, for such explicit treatment of pressure on outflow boundary, our experiments show instability if ν is not sufficiently large.…”
The paper introduces a finite difference solver for the unsteady incompressible Navier-Stokes equations based on adaptive cartesian octree grids. The method extends a stable staggered grid finite difference scheme to the graded octree meshes. It is found that a straightforward extension is prone to produce spurious oscillatory velocity modes on the fine-to-coarse grids interfaces. A local linear low-pass filter is shown to reduce much of the bad influence of the interface modes on the accuracy of numerical solution. We introduce an implicit upwind finite difference approximation of advective terms as a low dissipative and stable alternative to semi-Lagrangian methods to treat the transport part of the equations. The performance of method is verified for a set of benchmark tests: a Beltrami type flow, the 3D lid-driven cavity and channel flows over a 3D square cylinder.
“…We shall demonstrate in the series of numerical experiments that the scheme retains second order accuracy if t varies smoothly. In the case of outflow boundary conditions, building a second order accurate stable pressure projection method is a well-known problem, see, e.g., [24,25]. It is not our intention to address this problem in the present paper.…”
Section: Numerical Time-integrationmentioning
confidence: 97%
“…It is not our intention to address this problem in the present paper. If one sets ν ∂ u n+1 ∂n Γ 2 = p n n in (10), then Guermond et al [24] proved that the splitting method is up to 3 2 order the accurate (the actual order depends on a certain regularity index). However, for such explicit treatment of pressure on outflow boundary, our experiments show instability if ν is not sufficiently large.…”
The paper introduces a finite difference solver for the unsteady incompressible Navier-Stokes equations based on adaptive cartesian octree grids. The method extends a stable staggered grid finite difference scheme to the graded octree meshes. It is found that a straightforward extension is prone to produce spurious oscillatory velocity modes on the fine-to-coarse grids interfaces. A local linear low-pass filter is shown to reduce much of the bad influence of the interface modes on the accuracy of numerical solution. We introduce an implicit upwind finite difference approximation of advective terms as a low dissipative and stable alternative to semi-Lagrangian methods to treat the transport part of the equations. The performance of method is verified for a set of benchmark tests: a Beltrami type flow, the 3D lid-driven cavity and channel flows over a 3D square cylinder.
“…In particular, we aim to compare in the framework proposed in this paper the rotational incremental pressure-correction scheme, cf. [42], to an alternative strategy proposed in [61], which has demonstrated to improve the accuracy for the standard incremental version while remaining compatible with the rotational one ;…”
In this work, we address the solution of the Navier-Stokes equations (NSE) by a Finite Element (FE) Local Projection Stabilization (LPS) method. The focus is on a LPS method that has one level, in the sense that it is defined on a single mesh, and in which the projection-stabilized structure of standard LPS methods is replaced by an interpolation-stabilized structure, which only acts on the high frequency components of the flow. As a main contribution, we propose and test an efficient discretization of the model via a stable velocity-pressure segregation, using semi-implicit Backward Differentiation Formulas (BDF) in time. On the one hand, numerical studies illustrate that the solver accurately reproduces first and second-order statistics of benchmark turbulent flows for relatively coarse meshes. On the other hand, they show that the solver works in an efficient (i.e., robust and fast) way, especially when interfaced with scalable domain decomposition methods. Such scalability results are obtained on up to 16,384 cores with a near-ideal speedup.
“…As we mention in the introductory section, LG methods yield every time step a linear Stokes problem, in the previous numerical tests we solve such Stokes problems by a direct method; however, Achdou and Guermond (2000) and Guermond and Minev (2003) apply LG methods in combination with fractional steps schemes to decouple velocity and pressure in a way that in the first step a velocity is calculated by solving a viscous equation satisfying the boundary conditions, then the pressure is obtained by solving a Poisson equation with homogeneous Neumann boundary conditions if the boundary conditions for the velocity are of Dirichlet type on Γ (see [14] for the case in which the velocity is also subject to open boundary conditions), and finally the divergence free velocity is calculated by a projection of the viscous velocity onto a divergence free subspace. Specifically, the projection/LG method of Guermond, Achdou and Minev to calculate a numerical solution to ((1))-( (3)) is the following.…”
We review in this paper the development of Lagrange-Galerkin (LG) methods to integrate the incompressible Navier-Stokes equations (NSEs) for engineering applications. These methods were introduced in the computational fluid dynamics community in the early eighties of the past century, and at that time they were considered good methods for both their theoretical stability properties and the way of dealing with the nonlinear terms of the equations; however, the numerical experience gained with the application of LG methods to different problems has identified drawbacks of them, such as the calculation of specific integrals that arise in their formulation and the calculation of the flow trajectories, which somehow have hampered the applicability of LG methods. In this paper, we focus on these issues and summarize the convergence results of LG methods; furthermore, we shall briefly introduce a new stabilized LG method suitable for high Reynolds numbers.
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