A general stabilized formulation for incompressible fluid flow using finite calculus and the finite element method (original) (raw)

A Lagrangian finite element approach for the analysis of fluid-structure interaction problems

International Journal for Numerical Methods in Engineering, 2010

A Lagrangian finite element method for the analysis of incompressible Newtonian fluid flows, based on a continuous re-triangulation of the domain in the spirit of the so-called Particle Finite Element Method, is here revisited and applied to the analysis of the fluid phase in fluid-structure interaction problems. A new approach for the tracking of the interfaces between fluids and structures is proposed. Special attention is devoted to the mass conservation problem. It is shown that, despite its Lagrangian nature, the proposed combined finite element-particle method is well suited for large deformation fluid-structure interaction problems with evolving free surfaces and breaking waves. The method is validated against the available analytical and numerical benchmarks.

Recent ship hydrodynamics developments in the parallel two-fluid flow solver Alya

Computers & Fluids, 2013

a b s t r a c t CFD modeling of turbulent free surface flows has become an important tool in the design of ship hulls. A two-fluid flow solver that can predict the flow pattern, free surface shape and the forces on the ship hull is presented. The discretization is based on unstructured linear finite elements, tetrahedras and prisms. A Variational Multiscale Stabilization technique known as Algebraic Sub Grid Scale Stabilization (ASGS) is used to deal with convection dominated flows and allow for equal order velocity-pressure interpolations. A fixed grid method that captures the position of the interface with the Level Set technique is used to simulate the two-phase flow. The jump in the fluid properties is smoothed in a region close to the interface. Spalart Allmaras and SST k-x turbulence models have been tested without showing significant differences. The need to accurately predict the viscous forces on the ship hull has motivated the use of anisotropically refined prism elements close the hull. Such meshes have challenged the capabilities of the equation based reinitialization techniques that we had previously used for the Level Set method.

Finite element solution of the Navier—Stokes equations

Acta Numerica, 1993

In this paper an analysis of the incompressible flow has been carried out, from the very definition of the governing equations, up to the resolution of some practical problems, passing through the comprehensive study of the stabilized finite element techniques used in their resolution. As a consequence of this analysis, a code based upon a realistic interpretation of the forces has been written, which allows for the modelling of the open channel flow, with optimum results in the resolution of some benchmark and real flow problems related with the wastewater industry.

An arbitrary lagrangian-eulerian velocity potential formulation for fluid-structure interaction

Computers & Structures, 1993

Akrtraet-Finite element formations for gnid-structure interaction, assuming an inviscid &id, can be class&xi into two major categories: displacement-based formulations and potential-based formulations. Although displacement-based formulations have been used widely, the methods suffer from the presence of spurious circulation modes and locking behavior. Potential-based formulations are inherently irrotational and do not have the difficulties of the displacement-based formulations. Nevertheless most of the applications of these methods are still limited to cases with relatively small motions. We introduce in this paper an arbitrary Lagrangisn-Eulerian formulation using the velocity potential and the density as fluid variables. The fo~ulation can be applied to problems in which the fluid undergoes very large boundary motions and can be used equally well for both compressible and incompressible fluids. I. WTRODUCTION The inter~tion between fluids and structures can, in many practical engineering problems, significantly affect the response. of the structure and hence needs to be properly taken into account in the analysis.

Implementation of a stabilized finite element formulation for the incompressible Navier-Stokes equations based on a pressure gradient projection

International Journal for Numerical Methods in Fluids, 2001

We discuss in this paper some implementation aspects of a finite element formulation for the incompressible Navier–Stokes equations which allows the use of equal order velocity–pressure interpolations. The method consists in introducing the projection of the pressure gradient and adding the difference between the pressure Laplacian and the divergence of this new field to the incompressibility equation, both multiplied by suitable algorithmic parameters. The main purpose of this paper is to discuss how to deal with the new variable in the implementation of the algorithm. Obviously, it could be treated as one extra unknown, either explicitly or as a condensed variable. However, we take for granted that the only way for the algorithm to be efficient is to uncouple it from the velocity–pressure calculation in one way or another. Here we discuss some iterative schemes to perform this uncoupling of the pressure gradient projection (PGP) from the calculation of the velocity and the pressure, both for the stationary and the transient Navier–Stokes equations. In the first case, the strategies analyzed refer to the interaction of the linearization loop and the iterative segregation of the PGP, whereas in the second the main dilemma concerns the explicit or implicit treatment of the PGP. Copyright © 2001 John Wiley & Sons, Ltd.

Finite Element Analysis in Fluid Mechanics

Mathematical Analysis and Applications, 2019

In the last decades, the finite element method (FEM) in fluid mechanics applications has gained substantial momentum. FE analysis was initially introduced to solid mechanics. However, the progress in fluid mechanics problems was slower due to the non-linearities of the equations and inherent difficulties of the classical FEM to deal with instabilities in the solution of these problems. The main goal of this review is to analyze FEM and provide the theoretical basis of the approach mainly focusing on parabolic type of problems applied in fluid mechanics. Initially, we analyze the basics of FEM for the Stokes problem and we provide theorems for uniqueness and error estimates of the solution. We further discuss FE approaches for the solution of the advection–diffusion equation such as the stabilized FEM, the variational multiscale method, and the discontinuous Galerkin method. Finally, we extend the analysis on the non-linear Navier–Stokes equations and introduce recent FEM advancements.

A stabilized finite element formulation to solve high and low speed flows

Communications in Numerical Methods in Engineering, 2005

It is well known that numerical methods designed to solve the compressible Euler equations, when written in terms of conservation variables behave poorly in the incompressible limit, that is, when density variations are negligible. However, a change to pressure based variables seem to, partly, eliminate the problem by making the Jacobian matrices fully invertible whatever the ow regime may be. Despite this apparent beneÿt, the stabilization matrix plus discontinuity capturing operator (for the compressible regime) still need attention, since they tend to be ill behaved for either conservation or pressure variables. In this paper, we introduce a simple way of balancing two stabilizing matrices, one of them suitable for low Mach ows and the other one for supersonic ows, so that a wide range of ow regimes are covered with only one formulation. Comparison between conservation and pressure variables is made and numerical examples are shown to validate the method.

Modeling Free Surface Flows Using Stabilized Finite Element Method

Mathematical Problems in Engineering, 2018

This work aims to develop a numerical wave tank for viscous and inviscid flows. The Navier-Stokes equations are solved by timediscontinuous stabilized space-time finite element method. The numerical scheme tracks the free surface location using fluid velocity. A segregated algorithm is proposed to iteratively couple the fluid flow and mesh deformation problems. The numerical scheme and the developed computer code are validated over three free surface problems: solitary wave propagation, the collision between two counter moving waves, and wave damping in a viscous fluid. The benchmark tests demonstrate that the numerical approach is effective and an attractive tool for simulating viscous and inviscid free surface flows.

A finite element method for compressible and incompressible flows

SN Applied Sciences

In this study, we present a unified formulation of compressible and incompressible Navier-Stokes equations in the quasi-linear form for primitive variables. In this formulation, two thermodynamic parameters, coefficient of isothermal compressibility and coefficient of thermal expansion, are highlighted. The incompressible limit is obtained when the coefficients of isothermal compressibility and of thermal expansion are taken equal to zero and when the density is supposed constant. For the simulation of advection-dominated flows, a stabilized finite element method based on the Petrov-Galerkin formulation is proposed. The proposed unified formulation is tested and validated for different numerical simulations. Different test cases are processed, from simplified models to more elaborate models. Finally, we present the conclusions inspired by this work, as well as the perspectives envisaged.