Národní úložiště šedé literatury Nalezeno 7 záznamů.  Hledání trvalo 0.00 vteřin. 
Note on the mathematical analysis of the motion of a rigid body in a generalized incompressible Navier-Stokes fluid
Al Baba, H. ; Ghosh, Amrita ; Muha, B. ; Nečasová, Šárka
Wedeal with a fluid-structure interaction problem: a motion of the rigid body inside a bounded domain filled by a fluid. We consider a viscous incompressible fluid described by the generalized incompressible Navier-Stokes equations which include cases of Newtonian and non-Newtonian f luids. The fluid and the rigid body are coupled via the Navier slip boundary conditions and the motion of the solid is governed by Newton’s laws. We also investigate the case of the nonlinear slip condition.The main results assert the existence of strong solutions, in an Lp − Lq setting.
Numerical tests of vanishing diffusion stabilization in Oldroyd-B fluid flow simulations
Pires, M. ; Bodnár, Tomáš
This work presents some numerical tests of finite element solution of incompressible Oldroyd-B fluids flows, using different types of numerical stabilization. In this study the diffusive term (Laplacian of extra stress) is added to the tensorial constitutive relation where it is multiplied by a coefficient, that is variable in time. The goal is to make this diffusion coefficient vanish in time, so that the final solution remains unaffected by the added diffusion term. A series of numerical tests was performed for the steady two-dimensional Oldroyd-B fluid flow in corrugated channel (tube) to compare different versions of the vanishing stabilization terms and assess their efficiency in enforcing the solution convergence, without affecting the final steady state.
Second-order model for atmospheric turbulence without critical Richardson number
Caggio, M. ; Schiavon, M. ; Tampieri, F. ; Bodnár, Tomáš
The purpose of this communication is to present a derivation of the non-dimensional vertical gradients of the mean wind speed and mean potential temperature expressed in terms of the so-called similarity functions for very stable conditions of the atmosphere where theoretical approaches provide conflicting results (see e.g. Luhar et al. [19]). The result is based on the analysis of the second-order model equations in the boundary layer approximations in which new heat flux equations are proposed. The model employs a recent closure for the pressure-temperature correlation, avoiding the issue of a critical treshold for the Richardson number.
CFD Analysis of Flow in a Blade Cascade Deformed Due to Forced Torsional Vibration
Vomáčko, V. ; Šidlof, P. ; Šimurda, David ; Hála, Jindřich
The paper presents a 3D numerical simulation of flow in a blade cascade, whose geometry models the test section of a new experimental facility for blade flutter research. In the experimental setup, the middle blade of the cascade undergoes high-frequency forced sinusoidal pitching oscillation. Due to inertial forces, the slender blade deforms elastically to certain degree. The goal of this study is to assess the influence of the elastic deformation on the flow field. To compute the deformed geometry, a transient structural analysis was performed. In the second part, the CFD model of flow past a 3D blade cascade with deformed and undeformed blade is presented and these two configurations are compared. For the deformed configuration the incidence angle increases along the blade span from -1.8° to -2.7°. However, the Mach number distribution along the span varies less than expected. blade cascade, flutter, turbomachinery, CFD
Boundary Layer on the Flat Plate with Roughness Strip
Skála, Vladislav
Effect of the roughness strip on the boundary layer development on a flat plate was studied experimentally. A special model of a flat plate was designed. Experiment was made in non perturbed flow. Smooth flat plate (with super elliptical leading edge) was equipped with short roughness strip (close to the leading edge). Profiles of total pressure along the boundary layer were measured using flattened Pitot tube. First basic results of experiments are presented.
Comparison of Transonic Flows Through Two Tip-Section Turbine Blade Cascades with Different Flat Profiles
Musil, Josef ; Příhoda, Jaromír ; Fürst, J. ; Luxa, Martin ; Šimurda, David
The contribution deals with numerical simulations of 2D compressible flow through two variants of the tip-section turbine blade cascade with a flat profile for the subsonic inlet. Simulations were realised by means of the OpenFOAM code using the γ-Reθ bypass transition model completed by the two-equation SST turbulence model. Predictions were focused particularly on the impact of the shock-wave/boundary-layer interaction on the flow structure in the inter-blade channel. Beside the effect of the inlet angle on the flow around the leading edge was studied. Numerical results were compared with optical and pressure experimental data.
Proceedings of Topical Problems of Fluid Mechanics 2021
Bodnár, T. ; Neustupa, T. ; Šimurda, David
The aim of the conference is to publish and to discuss the latest results of theoretical, experimental and numerical research in fluid mechanics.

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