The lag model proposed by Olsen and Coakley (2001) is applied to simulate the steady and unsteady transonic flows in a diffuser. The unsteady flows are induced by imposing fluctuating back-pressures. A fully implicit time–accurate multigrid algorithm is used for solving the Navier-Stokes equations and the coupled k-ω turbulence model equations. Two test cases are investigated, one with a weak s...

This paper presents the development of a 2D high-order solver with spectral difference method for unsteady incompressible Navier–Stokes equations accelerated by a p-multigrid method. This solver is designed for unstructured quadrilateral elements. Time-marching methods cannot be applied directly to incompressible flows because the governing equations are not hyperbolic. An artificial compressib...

Granular surface flows have still to be fully modelled. Here, we present the four types of front that can be observed in avalanches. These strongly inhomogeneous and unsteady flows are very sensitive test cases for the different types of model. We show that, at least qualitatively for the moment, the model we propose, based on the analysis of the motion of a single grain and layers of grains, c...

In this paper, we study the steady and unsteady magneto hydro dynamic (MHD) viscous, incompressible free and forced convective flow of an electrically conducting Newtonian fluid through a porous medium in the presence of appreciable thermal radiation heat transfer and surface temperature oscillation taking hall current into account. The fluid is assumed to be optically-thin and magnetic Reynold...

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate single-shot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecon...

We look at multigrid methods for unsteady viscous compressible flows. We specifically target smoothers that can be used in parallel and without computation of a Jacobian, which are particlarly attractive candidates in the context of Discontinuous Galerkin discretizations. In CFD, a plethora of nonlinear smoothers have been suggested which are hard to analyze. Our methodology is to use a linear ...

Potential flow solvers for 3D aerodynamic flows are commonly used in industrial applications. Two main difficulties preventing the even more widespread use of these codes are the limitations on the number of discretization elements and the user expertise and effort required to specify the wake location. In the paper we present an automatic wake generation strategy for a potential flow solver, a...

We present the analysis and numerical simulations of incompressible Newtonian fluids for unsteady flows in a straight pipe and in deformed pipe with concave and convex deformation of the upper wall. An approach of modeling of blood flow is considered with an unsteady Navier-Stokes problem with a pulsatile flow for which we can establish analogy with existing cardio vascular systems. We apply th...

This paper presents the development of a 2D high-order solver with unstructured spectral difference method for unsteady incompressible Navier-Stokes equations. Timemarching methods cannot be applied directly to incompressible flows because the governing equations are not hyperbolic. An artificial compressibility method (ACM) is employed in order to treat the inviscid fluxes using the traditiona...

Although much progress has been made in the computation of Eulerian steady flows with high viscoelasticity, less work has been done for the case of transient flows. Because of their importance in injection moulding, blow moulding and other forming processes, as well as their intrinsic interest, we believe more attention should be focussed in this area. Hence in this paper we review progress in ...