The aim of this article is a qualitative analysis of two modern finite volume (FVM) schemes. First one is the so called Modified Causon's scheme, which is based on the classical MacCormack FVM scheme in total variation diminishing (TVD) form, but is simplified in such a way that the demands on computational power are much smaller without loss of accuracy. Second one is implicit WLSQR (Weighted Least Square Reconstruction) scheme combined with various types of numerical fluxes (AUSMPW+ and HLLC). Two different test cases were chosen for the comparison −1) two-dimensional transonic inviscid nonstationary flow over an oscillating NACA 0012 profile and 2) three-dimensional transonic inviscid stationary flow around the Onera M6 wing. Nonstationary effects were simulated with the use of Arbitrary Lagrangian-Eulerian Method (ALE). Experimental results for these regimes of flow are easily available and so the numerical results are compared both in-between and with experimental data. The obtained numerical results in all considered cases (2D and 3D) are in a good agreement with experimental data.
The article deals with the numerical simulation of unstable, incompressible flows with stratifications. The mathematical model is based on the Boussinesq approximation of the Navier-Stokes equations. The flow field in the towing tank with a moving cylinder is modeled for wide range of Richardson numbers. The obstacle is modeled via appropriate source terms. The resulting set of PDE is then solved by the fifth oorder WENO scheme, or by a second order finite volume AUSM MUSCL scheme. Both schemes are combined with the artificial compressibility method in dual time. and Obsahuje seznam literatury
The article deals with the numerical solution of transitional flows. The single-point k-kL-ω model of [7] based on the use of a laminar kinetic energy transport equation is considered. The model doesn‘t require to evaluate integral boundary layer parameters (e.g. boundary layer thickness) and is therefore suitable for implementation into codes working with general unstructured meshes. The performance of the model has been tested for the case of flows over a flat plate with zero and non-zero pressure gradients. The results obtained with our implementation of the model are compared to the experimental data of ERCOFTAC. and Obsahuje seznam literatury
This study deals with the numerical solution of a 2D unsteady flow of a compressible viscous fluid in a channel for low inlet airflow velocity. The unsteadiness of the flow is caused by a prescribed periodic motion of a part of the channel wall with large amplitudes, nearly closing the channel during oscillations. The channel is a simplified model of the glottal space in the human vocal tract and the flow can represent a model of airflow coming from the trachea, through the glottal region with periodically vibrating vocal folds to the human vocal tract.
The flow is described by the system of Navier-Stokes equations for laminar flows. The numerical solution is implemented using the finite volume method (FVM) and the predictor-corrector MacCormack scheme with Jameson artificial viscosity using a grid of quadrilateral cells. Due to the motion of the grid, the basic system of conservation laws is considered in the Arbitary Lagrangian-Eulerian (ALE) form.
The authors present the numerical simulations of flow fields in the channel acquired from a program developed exclusively for this purpose. The numerical results for unsteady flows in the channel are presented for inlet Mach number M∞ = 0.012, Reynolds number Re∞ = 5x103 and the wall motion frequency 100 Hz. and Obsahuje seznam literatury
The paper deals with the experimental and numerical research of flows through prismatic turbine cascade in transonic regimes. The primary goal is to evaluate the influence of the non-uniformity of the inlet velocity profile to the span-wise distribution of energy losses. The numerical simulation with inlet velocity profile corresponding to the parameters of the flow in high speed wind tunnel in Nový Knín is compared with the experimental data. and Obsahuje seznam literatury