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 contribution presents a mathematical and numerical investigation of the Atmospheric Boundary Layer (ABL) flow over the real configuration given by a brown coal mine and coal depot in North Bohemia. The influence of various types of protective
obstacles (as forest blocks, tree-line, walls) on the reduction of dustiness has been studied.
The mathematical models are based on the system of Reynolds Averaged Navier-Stokes (RANS) equations for a viscous incompressible flow. The full system of RANS equations in conservative form was solved using finite-volume explicit scheme and artificial compressibility method. A simple algebraic turbulent model was used for the closure of the basic system of equations. Additional transport equation for passive pollutant has been considered in order to study the pollution dispersion over the
complex 3D topography. The forest stand is simulated using the additional source term in the momentum equations which depends on the local velocity magnitude, the characteristic area of the obstacle and on the drag coefficient. 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 a flow validation study performed using our in-house 3D-computer-code which implements mathematical and numerical model capable to simulate the atmospheric boundary layer flow in general. The validation study is related to a neutrally stratified boundary layer 2D-flow over an isolated hill with a rough wall including pollution dspersion according to Castro [1].
Our mathematical model is based on the system of RANS equations closed by two-equation high-Reynolds number k-ε turbulence model together with wall functions. The finite volume method and the explicit Runge-Kutta time integration method are utilized for the numerics. and Obsahuje seznam literatury