Publications related to Transonic

An improved analytical framework for flow prediction inside and downstream of wind farms

This study evaluates available analytical wake models for flow prediction inside and downstream of wind farms of different sizes and layouts using large-eddy simulation (LES), and introduces an enhanced analytical framework. All the tested analytical wake ...

Pergamon-Elsevier Science Ltd2024

Measurement and modelling of dynamic fluid saturation in carbon reinforcements

Véronique Michaud, Baris Çaglar, Helena Luisa Teixido Pedarros, Guillaume Clément Broggi

We propose a methodology to monitor the progressive saturation of a non-translucent unidirectional carbon fabric stack through its thickness by means of X-ray radiography and extract the dynamic saturation curves using image analysis. Four constant flow ra ...

2023

Model order reduction for compressible flows solved using the discontinuous Galerkin methods

Jan Sickmann Hesthaven

Projection-based reduced order models (ROM) based on the weak form and the strong form of the discontinuous Galerkin (DG) method are proposed and compared for shock-dominated problems. The incorporation of dissipation components of DG in a consistent manne ...

ACADEMIC PRESS INC ELSEVIER SCIENCE2022

Fourier Collocation and Reduced Basis Methods for Fast Modeling of Compressible Flows

Jan Sickmann Hesthaven, Deep Ray

A projection-based reduced order model (ROM) based on the Fourier collocation method is proposed for compressible flows. The incorporation of localized artificial viscosity model and filtering is pursued to enhance the robustness and accuracy of the ROM fo ...

GLOBAL SCIENCE PRESS2022

Experimental quantification of unsteady leading-edge flow separation

Karen Ann J Mulleners, Julien Dominique Claude Deparday

We propose here a method to experimentally quantify unsteady leading-edge flow separation on aerofoils with finite thickness. The methodology relies on the computation of a leading-edge suction parameter based on measured values of the partial circulation ...

Cambridge University Press2022

Comparative study between Cubic and Ellipsoidal Fokker-Planck kinetic models

Mohammadhossein Gorji

Motivated by improving the performance of particle-based Monte-Carlo simulations in the transitional regime, Fokker–Planck kinetic models have been devised and studied as approximations of the Boltzmann collision operator. By generalizing the linear drift ...

2019

Two-fluid plasma model for radial Langmuir probes as a converging nozzle with sonic choked flow, and sonic passage to supersonic flow

Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne

Using the Lambert function, Guittienne et al. [Phys. Plasmas 25, 093519 (2018)] derived two-fluid solutions for radial Langmuir probes in collisionless and isothermal plasma. In this Brief Communication, we point out the close analogy with classical compre ...

American Institute of Physics (AIP)2019

Coherent Structure Interaction During Unsteady Separation

Karen Ann J Mulleners

Unsteady flow separation in rotationally augmented flow fields plays a significant role in the aerodynamic performance of industrial rotors, including wind turbines. Current computational models underestimate the aerodynamic loads due to the inaccurate pre ...

2019

Sub-Kelvin stereodynamics of the Ne(3P2)+N2 reaction

Andreas Osterwalder, Sean Dennis Steven Gordon, Junwen Zou

We present an experimental study of the low-energy stereodynamics of the Ne(3P2)+N2 reaction. Supersonic expansions of the two reactants are superposed in a merged beam experiment, where individual velocity control of the two beams allows us to reach avera ...

AMER PHYSICAL SOC2019

Non-intrusive reduced-order modeling for fluid problems: A brief review

Mengwu Guo

Despite tremendous progress seen in the computational fluid dynamics community for the past few decades, numerical tools are still too slow for the simulation of practical flow problems, consuming thousands or even millions of computational core-hours. To ...

SAGE PUBLICATIONS LTD2019

Spatially Sampled Pressure Profile Measurements in Externally Pressurized Gas Journal Bearings

Jürg Alexander Schiffmann, Eliott Philippe Guenat, Karim Magdi Zakaria Abdelrahman Shalash

Externally pressurized gas journal bearings (EPGJB) are widely adopted to support high speed rotors. This paper presents novel experimental benchmark test data which enables EPGJB model validation. Axial and circumferential pressure profile measurements ar ...

2018

The Role of Impeller Outflow Conditions on the Performance of Vaned Diffusers

Jürg Alexander Schiffmann

Highly loaded impellers, typically used in turbocharger and gas turbine applications, exhaust an unsteady, transonic flow that is nonuniform across the span and pitch and swirling at angles approaching tangential. With the exception of the flow angle, conf ...

American Society of Mechanical Engineers2017

The microfluidic nebulator: production of submicrometer sized airborne drops

Esther Amstad

Many powders employed in the food and pharmaceutical industries are produced through spray drying because it is a cost efficient process that offers control over the particle size. However, most commercially available spray-driers cannot produce drops with ...

Royal Soc Chemistry2017

Multi Level Monte Carlo Methods for Uncertainty Quantification and Robust Design Optimization in Aerodynamics

Michele Pisaroni

The vast majority of problems that arise in aircraft production and operation require decisions to be made in the presence of uncertainty. An effective and accurate quantification and control of the level of uncertainty introduced in the design phase and d ...

EPFL2017

NANOPARTICLES Production of amorphous nanoparticles by supersonic spray-drying with a microfluidic nebulator

Esther Amstad

Amorphous nanoparticles (a-NPs) have physicochemical properties distinctly different from those of the corresponding bulk crystals; for example, their solubility is much higher. However, many materials have a high propensity to crystallize and are difficul ...

American Association for the Advancement of Science2015

High Voltage Pulsed DBD Effects on the Aerodynamic Performances and on the Shock Buffet

Christoph Hollenstein, Peter Ott, Pénélope Leyland, Philip Peschke

The applications of surface dielectric barrier discharge plasma actuators, (DBD), have known a considerable interest recently in the field of flow control. In general, such actuators consist of two electrodes separated by an insulation covering the lower e ...

2013

Algorithmes d'adaptation de maillages anisotropes et application à l'aérodynamique

Wissam Hassan

The goal of this thesis is to study an anisotropic adaptive algorithm for transonic compressible viscous flow around an airwing. A convection-diffusion model problem is considered, an anisotropic a posteriori error estimator for the H1 semi-norm of the err ...

EPFL2012

Counterpropagating Rossby waves in confined plane wakes

François Gallaire, Luca Biancofiore

In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity ca ...

American Institute of Physics2012

Characterization of the Flow Generated in an Annular Test Facility

Peter Ott, Elia Colombo, Dominique Charbonnier, Cécile Deslot

Annular cascades are particularly useful to study the three dimensional phenomena encountered in turbomachines. The Non-Rotating Annular Test Facility of the Swiss Federal Institute of Technology in Lausanne (EPFL) consists in a radial-axial inlet nozzle a ...

2011