Search results for "Reynolds"

Numerical and experimental investigation of a cross-flow water turbine

2016

ABSTRACTA numerical and experimental study was carried out for validation of a previously proposed design criterion for a cross-flow turbine and a new semi-empirical formula linking inlet velocity to inlet pressure. An experimental test stand was designed to conduct a series of experiments and to measure the efficiency of the turbine designed based on the proposed criterion. The experimental efficiency was compared to that from numerical simulations performed using a RANS model with a shear stress transport (SST) turbulence closure. The proposed semi-empirical velocity formula was also validated against the numerical solutions for cross-flow turbines with different geometries and boundary c…

Effect of the junction angle on turbulent flow at a hydraulic confluence

2018

Despite the existing knowledge concerning the hydrodynamic processes at river junctions, there is still a lack of information regarding the particular case of low width and discharge ratios, which are the typical conditions of mountain river confluences. Aiming at filling this gap, laboratory and numerical experiments were conducted, comparing the results with literature findings. Ten different confluences from 45 ∘ to 90 ∘ were simulated to study the effects of the junction angle on the flow structure, using a numerical code that solves the 3D Reynolds Averaged Navier-Stokes (RANS) equations with the k- ϵ turbulence closure model. The results showed that the higher the junction angle, the …

A boundary condition for arbitrary shaped inlets in lattice-Boltzmann simulations

2009

We introduce a mass-flux-based inlet boundary condition for the lattice-Boltzmann method. The proposed boundary condition requires minimal amount of boundary data, it produces a steady-state velocity field which is accurate close to the inlet even for arbitrary inlet geometries, and yet it is simple to implement. We demonstrate its capability for both simple and complex inlet geometries by numerical experiments. For simple inlet geometries, we show that the boundary condition provides very accurate inlet velocities when Re less than or similar to 1. Even with moderate Reynolds number, the inlet velocities are accurate for practical purposes. Furthermore, the potential of our boundary condit…

Alastair Reynolds: Ikirouta

2020

Kirja-arvostelu teoksesta Alastair Reynolds: Ikirouta, suom. Hannu Tervaharju, Like SciFi, 2020 nonPeerReviewed

Écriture et perception des grandes formes en musique contemporaine et, en particulier, chez Roger Reynolds. « Le cristal et la flamme »

2003

This PhD addresses the issue of musical time and form in the second half of the XXth century with the joint perspective of composition and perception. The first chapter describes composer’s main conceptions of musical time, compositional strategies, functions and formal models, as well as the main musicological theories concerning musical form. The second chapter is devoted to the semiotic square of musical form (definition, typological and syntagmatic approach). The third chapter is dedicated to R. Reynolds’The Angel of Death, a work that allows us to compare writing and perception. The fourth chapter reviews the main studies and theories forged by psychology around this question, and pres…

Quantum Reynolds number for superfluid counterflow turbulence

2013

On Stability of a Concentrated Fiber Suspension Flow

2014

Linear stability analysis of a fiber suspension flow in a channel domain is performed using a modified Folgar-Tucker equation. Two kinds of potential instability are identified: one is associated with overcritical Reynolds number and another is associated with certain perturbations in fiber orientation field and is present for any Reynolds numbers. The second type of instability leads to initially growing transient perturbations in the microstructure. It is shown that both types of instability lead to instability of the bulk velocity field. As for the perturbed Orr-Sommerfeld eigenvalues, the presence of fibers increases the stability region; the stability region increases with growing C i …

Weak Maximum Principle and Application to Swimming at Low Reynolds Number

2018

We refer to [9, 42, 46] for more details about the general concepts and notations introduced in this section.

Demo 70. Turbulencia

2013

Objetivos: Comprender la utilizad del número de Reynolds para predecir la ocurrencia de turbulencia.

High-Reynolds-number turbulent cavity flow using the lattice Boltzmann method

2018

We present a boundary condition scheme for the lattice Boltzmann method that has significantly improved stability for modeling turbulent flows while maintaining excellent parallel scalability. Simulations of a three-dimensional lid-driven cavity flow are found to be stable up to the unprecedented Reynolds number $\mathrm{Re}=5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ for this setup. Excellent agreement with energy balance equations, computational and experimental results are shown. We quantify rises in the production of turbulence and turbulent drag, and determine peak locations of turbulent production.