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16082. Numerical simulation of aeroelastic problems with consideration of nonlinear effects
- Creator:
- Sváček, Petr
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- aeroelasticity, finite element method, and Arbitrary Lagrangian Eulerian method
- Language:
- English
- Description:
- In this paper the numerical approximation of a two dimensional aeroelastic problem is addressed, where nonlinear effects are considered. For the flow model we use the Navier-Stokes equations, spatially discretized by the FE method and stabilized with a modification of the Galerkin Least Squares (GLS) method. The motion of the computational domain is treated with the aid of the Arbitraty Lagrangian Eulerian (ALE) method. The structure model is considered as a solid body with two degrees of freedom (bending and torsion). The motion is described with the aid of a system of nonlinear differential equations and coupled with the flow model by the strongly coupled algorithm. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16083. Numerical simulation of fly-ash transport in three sands of different particle-size distributions using HYDRUS-1D
- Creator:
- Kodešová, Radka, Kapička, Aleš, Lebeda, Jakub, Grison, Hana, Kočárek, Martin, and Petrovský, Eduard
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- sand, fly-ash migration, magnetic susceptibility, numerical simulation, attachment/detachment concept, filtration theory, písek, migrace úletového popílku, magnetická susceptibilita, numerická simulace, attachment/detachment koncept, and filtrační teorie
- Language:
- Slovak
- Description:
- Study is focused on the numerical modeling of fly-ash transport in three sands, which was experimentally studied in the laboratory. Sands were packed in glass cylinders with diameter of 5.52 cm and height of 18 cm. Sands were also packed in plastic cylinders with diameter of 30 cm and height of 40 cm. The fly-ash and pulse infiltrations were applied on the top of all cylinders. Visually observed and gravimetrically evaluated fly-ash migration in small cylinders corresponded to fly-ash mobility in large columns detected using the SM400 Kappameter. The HYDRUS-1D code was used to simulate observed fly-ash transport. Parameters of soil hydraulic functions were either obtained using the Tempe cells and the RETC program or estimated using numerical inversion of transient water flow data measured in both types of columns using HYDRUS-1D. Parameters characterizing colloid transport in sands were then estimated from the final fly-ash distribution in sandy columns using attachment/detachment concept in HYDRUS-1D. Fly-ash mobility increased with increasing sand particle sizes, e.g. pore sizes. Particle sizes and pore water velocity influenced the attachment coefficient, which was calculated assuming filtration theory. The same longitudinal dispersivity, sticking efficiency and detachment coefficient sufficiently characterized fly-ash behavior in all sands. and Studie je zaměřena na numerické modelování transportu úletového popílku ve třech píscích, který byl experimentálně studován v laboratoři. Písky byly nahutněny ve skleněných válcích o průměru 5,52 cm a výšce 18 cm. Písky byly také nahutněny v plastových válcích o průměru 30 cm a výšce 40 cm. Na povrchu válců byly aplikovány jednorázové infiltrace vody s popílkem. Migrace úletového popílku pozorovaná vizuálně a zjištěná gravimetricky v malých válcích odpovídala mobilitě úletového popílku detekované Kappametrem SM400 ve velkých válcích. Pozorovaný transport úletového popílku byl simulován programem HYDRUS-1D. Parametry hydraulických funkcí byly získány buď pomocí Tempských cel a programu RETC nebo odhadovány numerickou inverzí transientních data měřených na obou typech válců programem HYDRUS-1D. Parametry charakterizující transport koloidů v píscích byly potom odhadovány z konečné distribuce úletového popílku v písčitých sloupcích užitím konceptu attachment/detachment (připojení/odpojení) v programu HYDRUS-1D. Mobilita úletového popílku se zvyšovala se zvyšující se velikostí písčitých zrn, tj. s velikostí pórů. Velikost zrn a pórová rychlost ovlivnila depoziční (attachment) koeficient, který byl počítán na základě filtrační teorie. Stejné hodnoty podélné disperze, efektivity blokování (sticking efficiency) a mobilizačního (detachement) koeficientu charakterizovaly chování úletového popílku ve všech píscích.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16084. Numerical simulation of influence of various types obstacles on dustiness of coal depot
- Creator:
- Beneš, Luděk, Kozel, Karel, and Sládek, Ivo
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- finite volume, artificial compressibility, ABL, and pollution dispersion
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16085. Numerical simulation of suspension induced rheology
- Creator:
- Prignitz, Rudolphe and Bänsch, Eberhard
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- CFD, multiphase flows, particulate flow, finite elements, subspace projection, and rheology
- Language:
- English
- Description:
- Flow of particles suspended in a fluid can be found in numerous industrial processes utilizing sedimentation, fluidization and lubricated transport such as food processing, catalytic processing, slurries, coating, paper manufacturing, particle injection molding and filter operation. The ability to understand rheology effects of particulate flows is elementary for the design, operation and efficiency of the underlying processes. Despite the fact that particle technology is widely used, it is still an enormous experimental challenge to determine the correct parameters for the process employed. In this paper we present \mbox{2-dimensional} numerical results for the behavior of a particle based suspension and compare it with analytically results obtained for the Stokes-flow around a single particle.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
16086. Numerical simulation of the stratified flow using high order schemes
- Creator:
- Beneš, Luděk, Fürst, Jiří, and Fraunie, Philippe
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- stratified flow, towing tank, Boussinesq approximation, finite volume, and WENO artificial compressibility
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16087. Numerical simulation of three-phase flow with a virtual mass effect
- Creator:
- Dolejší, Vít and Gallouët, Thierry
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- solid-liquid-gas slurries, virtual mass effect, Rusanov scheme, MUSCL approach, finite volume methods, and steady and unsteady flow simulation
- Language:
- English
- Description:
- We deal with the numerical simulation of a flow of solid-liquid-gas slurries with the virtual mass effect. The governing systmn of equations is strongly nonlinear hyperbolic with nonconservative terms. We propose a numerical scheme which belongs to the class of finite volume methods. In order to increase the order of convergence we apply a higher order reconstruction technique. Several numerical examples demonstrating the efficiency of the schemes are presented. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16088. Numerical simulation of transitional flows with laminar kinetic energy
- Creator:
- Fürst, Jiří
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- turbulence, transition, and Navier-Stokes equation
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16089. Numerical simulation of unsteady compressible low Mach number flow in a channel
- Creator:
- Punčochářová-Pořízková, Petra, Kozel, Karel, Horáček, Jaromír, and Fürst, Jiří
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- CFD, Finite Volume Method, unsteady flow, low Mach number, and viscous compressible fluid
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
16090. Numerical simulation on a mixed-flow pump operating in a turbine mode
- Creator:
- Hlbočan, Peter and Varchola, Michal
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- reversible machine, turbine impeller, pump impeller, and performance characteristics
- Language:
- English
- Description:
- The paper deals with a modeling of a flow in hydraulic parts of a turbo machine operating in a pump and in a turbine mode. The results are Q-H (Q-Y) performance characteristics of the pump operating in both modes. An important piece of knowledge is a shift of the pump‘s and turbine‘s BEP and the change of specific speeds of the turbo machine in a pump and in a turbine mode, which emerges from it. The goal of this paper was to find a shift of pump‘s and turbine‘s BEP and to obtain information about hydraulic efficiency of the pump operating in a pump and turbine mode. Anyway the aim of CFD simulation is to evaluate Q-H (Q-Y) characteristic from the point of view of a stability of Q-H curve. The analysis of flow patterns in the impeller and in the vane diffuser in a pump and turbine mode is a valuable contribution to the topic of a hydraulic interaction between an impeller and a vane diffuser. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public