Showing papers by "H. Bijl published in 2005"
TL;DR: It is shown that with a minimal coding effort the standard non-linear multigrid method can be combined with a Newton–Krylov method leading to speed-ups in the order of 30% in iterative techniques for unsteady flow computations with implicit higher order time integration methods at large time steps.
Abstract: In this paper iterative techniques for unsteady flow computations with implicit higher order time integration methods at large time steps are investigated. It is shown that with a minimal coding effort the standard non-linear multigrid method can be combined with a Newton–Krylov method leading to speed-ups in the order of 30%. Copyright © 2005 John Wiley & Sons, Ltd.
21 citations
TL;DR: In this article, the authors investigate local adaptive refinement of unstructured hexahedral meshes for computations of the flow around the DU91 wind turbine airfoil, finding at the mid-span section of a wind turbine blade.
Abstract: We investigate local adaptive refinement of unstructured hexahedral meshes for computations of the flow around the DU91 wind turbine airfoil. This is a 25% thick airfoil, found at the mid-span section of a wind turbine blade. Wind turbine applications typically involve unsteady flows due to changes in the angle of attack and to unsteady flow separation at high angles of attack. In order to obtain reasonably accurate results for all these conditions one should use a mesh which is refined in many regions, which is not computationally efficient. Our solution is to apply an automated mesh adaptation technique. In this paper we test an adaptive refinement strategy developed for unstructured hexahedral meshes for steady flow conditions. The automated mesh adaptation is based on local flow sensors for pressure, velocity, density or a combination of these flow variables. This way the mesh is refined only in those regions necessary for high accuracy, retaining computational efficiency. A validation study is performed for two cases: attached flow at an angle of 6° and separated flow at 12°
9 citations
TL;DR: This paper investigates the efficiency of higher-order time integration schemes compared to lower-order methods in nonlinear fluid–structure interaction (FSI) simulations and finds that the latter are more efficient than the former.
Abstract: In this paper higher-order time integration schemes are applied to nonlinear fluid–structure interaction (FSI) simulations. For a given accuracy, we investigate the efficiency of higher-order time integration schemes compared to lower-order methods. In the partitioned FSI simulations on a one-dimensional piston problem, a mixed implicit/explicit (IMEX) time integration scheme is employed: the implicit scheme is used to integrate the fluid and structural dynamics, whereas an explicit Runge–Kutta scheme integrates the coupling terms. The resulting IMEX scheme retains the order of the implicit and explicit schemes. In the IMEX scheme considered, the implicit scheme consists of an explicit first stage, singly diagonally implicit Runge–Kutta (ESDIRK) scheme, which is a multi-stage, L-stable scheme.
7 citations
01 Jan 2005
TL;DR: In this article, the effect of strong and weak boundary conditions on the numerical adjoint solution near the boundaries is compared with boundary condition treatments applied to the quasi-1D Euler equations.
Abstract: This work compares a numerical and analytical adjoint equation method with respect to boundary condition treatments applied to the quasi-1D Euler equations. The effect of strong and weak boundary conditions and the effect of flux evaluators on the numerical adjoint solution near the boundaries are discussed.
1 citations