Results from outdoor acoustic measurements performed in a railway site near Reims in France in May 2010 are compared to those obtained from a finite-difference time-domain solver of the linearized Euler equations. During the experiments, the ground profile and the different ground surface impedances were determined. Meteorological measurements were also performed to deduce mean vertical profile...

An unsteady two-dimensional numerical investigation was performed on the viscous flow passing through a multi-blade cascade. A Cartesian finite-volume approach was employed and it was linked to Van-Leer's and Roe's flux splitting schemes to evaluate inviscid flux terms. To prevent the oscillatory behavior of numerical results and to increase the accuracy, Monotonic Upstream Scheme for Conservat...

We present a numerical method to solve the equations of general relativistic hydrodynamics in a given external gravitational field. The method is based on a generalization of Roe’s approximate Riemann solver for the non relativistic Euler equations in Cartesian coordinates. The new method is applied to a set of standard test problems for general relativistic hydrodynamics, and is shown to perfo...

A method for adaptive refinement of a Cartesian mesh for the solution of the steady Euler equations is presented. The algorithm creates an initial uniform mesh and cuts the body out of that mesh. The mesh is then refined based on body curvature. Next, the solution is converged to a steady state using a linear reconstruction and Roe's a p proximate Riemann solver. Solution-adaptive refinement of...

Numerical solution of the stationary navier-stokes equations by means of a multiple grid method and newton iteration. Distributive iterationen f ur indeenite Systeme als Gll atter in Mehrgitter-verfahren am Beispiel der Stokes-und Navier-Stokes-Gleichungen mit Schwerpunkt auf unvollstt andingen Zerlegungen. PhD thesis, Christan-Albrechts Universitt at, Kiel, 1986. 145. G. Wittum. Linear iterati...

In this paper, we present an evolutionary algorithm hybridized with a gradient-based optimization technique in the spirit of Lamarckian learning for efficient design optimization. In order to expedite gradient search, we employ local surrogate models that approximate the outputs of a computationally expensive Euler solver. Our focus is on the case when an adjoint Euler solver is available for e...

This work is concerned with the simulation of inviscid compressible flow in time dependent domains. We present an ALE (Arbitrary Lagrangian-Eulerian) formulation of the Euler equations describing compressible flow, discretize them in space by the discontinous Galerkin method and introduce a semi-implicit linearized time stepping for the numerical solution of the complete problem. Special attent...

In this paper we treat subjects which are relevant in the context of iterative methods in implicit time integration for compressible flow simulations. We present a novel renumbering technique, some strategies for choosing the time step in the implicit time integration, and a novel implementation of a matrix-free evaluation for matrix-vector products. For the linearized compressible Euler equati...

We derive novel, fast, and effective preconditioned iterative methods for steady time-dependent Navier--Stokes control problems. Our approach may be applied to problems which are discretized using backward Euler or Crank--Nicolson is also a valuable candidate Stokes Crank--Nicolson. The key ingredients of the solver saddle-point type approximation linear systems, an inner iteration $(1,1)$-bloc...

We implement a second-order exponential integrator for semidiscretized advectiondiffusion-reaction equations, obtained by coupling exponential-like Euler and Midpoint integrators, and computing the relevant matrix exponentials by polynomial interpolation at Leja points. Numerical tests on 2D models discretized in space by Finite Differences or Finite Elements, show that the Leja-Euler-Midpoint ...