Publications related to Grashof number

Scaling behavior of bedload transport: what if Bagnold was right?

There is a paradox in the relationship between bedload transport rates and flow variables: laboratory and field studies have reported on how bedload transport rates depend on flow variables through a power law, but none of the empirical laws fitted to the ...

2023

Convection of snow: when and why does it happen?

Michael Lehning, Mahdi Jafari

Convection of water vapor in snowpacks is supposed to have a major impact on snow density and microstructure profiles with strong implications for the thermal regime and snow stability. However, the process has never been directly measured and only recentl ...

FRONTIERS MEDIA SA2023

Dissipative magnetic structures and scales in small-scale dynamos

Jennifer Waltraud Schober

Small-scale dynamos play important roles in modern astrophysics, especially on galactic and extragalactic scales. Owing to dynamo action, purely hydrodynamic Kolmogorov turbulence hardly exists and is often replaced by hydromagnetic turbulence. Understandi ...

OXFORD UNIV PRESS2023

Convection of water vapour in snowpacks

Varun Sharma, Michael Lehning, Mahdi Jafari

This paper studies numerically the convection of water vapour in snowpacks using an Eulerian-Eulerian two-phase approach. The convective water vapour transport in snow and its effects on snow density are often invoked to explain observed density profiles, ...

Cambridge University Press2022

Evaluation Criterion of Proton Exchange Membrane (ECPEM) fuel cells considering inserted porous media inside the gas flow channel

Jan Van Herle, Hossein Pourrahmani

The focus of this study is to evaluate the effects of porous media inside the gas flow channel of Proton Exchange Membrane Fuel Cells (PEMFC) on four different output parameters of voltage, power density, pressure drop, and Nusselt number (Nu) considering ...

PERGAMON-ELSEVIER SCIENCE LTD2022

A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

Sebastiano Piccolroaz, Bieito Fernandez Castro, Marco Toffolon

A multi-site, year-round dataset comprising a total of 606 high-resolution turbulence microstructure profiles of shear and temperature gradient in the upper 100 m depth is made available for Lake Garda (Italy). Concurrent meteorological data were measured ...

2021

Inhibited vertical mixing and seasonal persistence of a thin cyanobacterial layer in a stratified lake

Alfred Johny Wüest, Damien Bouffard, Oscar Rodrigo Sepúlveda Steiner, Bieito Fernandez Castro

Harmful blooms of the filamentous cyanobacteria Planktothrix rubescens have become common in many lakes as they have recovered from eutrophication over the last decades. These cyanobacteria, capable of regulating their vertical position, often flourish at ...

2021

Parallel convection and E × B drifts in the TCV snowflake divertor and their effects on target heat-fluxes

Basil Duval, Holger Reimerdes, Joaquim Loizu Cisquella, Roberto Maurizio, Davide Galassi, Cedric Kar-Wai Tsui, Mirko Wensing

Parallel convection and E × B drifts act together to redistribute heat between the strike-points mechanisms is enhanced near the secondary X-point and is shown to dominate over heat in the low field side snowflake minus (LFS SF−). The cumulative heat conve ...

IOP Publishing Ltd2021

Thermal transport beyond Fourier, and beyond Boltzmann

Michele Simoncelli

Crystals and glasses exhibit fundamentally different heat conduction mechanisms: the periodicity of crystals allows for the excitation of propagating vibrational waves that carry heat, as first discussed by Peierls in 1929, while in glasses the lack of per ...

EPFL2021

Continuously-fed density currents over impermeable and porous substrates

Sara Venuleo

Gravity currents are buoyancy-driven flows having a significant impact on the environment and human life. They can be observed in a vast range of natural and anthropogenic scenarios, such as seawater and freshwater, the atmosphere, or industrial processes. ...

EPFL2020

Numerical investigation of the convection heat transfer driven by airflows in underground tunnels

Lyesse Laloui, Alessandro Francesco Rotta Loria, Margaux Marie Valérie Peltier

This study presents a fundamental investigation of the convection heat transfer phenomenon driven by airflows in underground tunnels, with reference to the development of the so-called thermal and velocity boundary layers. The purpose of the work is to exp ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Cfd-Based Correlation For Forced Convection Heat Transfer In Circular Ducts Of Internally Heated Molten Salts

Carlo Fiorina

Heat transfer phenomena involving internally heated fluid flows are of particular interest in several industrial applications, in chemical plants as in the nuclear field. This topic is relevant for the development of the Molten Salt Reactors (MSRs) since i ...

AMER SOC MECHANICAL ENGINEERS2018

Large Eddy Simulations of sediment entrainment induced by a lock-exchange gravity current

Carmelo Juez Jiménez, Jessica Zordan, Foteini Kyrousi, Alessandro Leonardi

Large Eddy simulations of lock-exchange gravity currents propagating over a mobile reach are presented. The numerical setting allows to investigate the sediment pick up induced by the currents and to study the underlying mechanisms leading to sediment entr ...

2018

3D Boundary Element Simulation of Droplet Dynamics in Microchannels: How Droplets Squeeze Through Constrictions and Move in Electric Fields

Simon Sebastian Schütz

Flows of fluids with free surfaces show complex dynamical behavior. Examples include effects like capillary surface waves, topological transitions such as droplet breakup and coalescence, or pattern formation in wetting and de-wetting dynamics. These compl ...

EPFL2018

Katabatic Flow: A Closed-Form Solution with Spatially-Varying Eddy Diffusivities

Peter Monkewitz, Jiannong Fang, Marco Giovanni Giometto, Marc Parlange

The Nieuwstadt closed-form solution for the stationary Ekman layer is generalized for katabatic flows within the conceptual framework of the Prandtl model. The proposed solution is valid for spatially-varying eddy viscosity and diffusivity (O'Brien type) a ...

Springer Verlag2017

Direct numberical simulation of turbulent slope flows up to Grash of number Gr=2.1 x 10(11)

Jiannong Fang, Marc Parlange, Marco Giovanni Giometto, Gabriel George Katul

Stably stratified turbulent flows over an unbounded, smooth, planar sloping surface at high Grashof numbers are examined using direct numerical simulations ( DNS). Four sloping angles ( alpha = 15 degrees; 30 degrees; 60 degrees and 90 degrees) and three G ...

Cambridge University Press2017

Identification of a Predator-Prey System from Simulation Data of a Convection Model

Jan Sickmann Hesthaven

The use of low-dimensional dynamical systems as reduced models for plasma dynamics is useful as solving an initial value problem requires much less computational resources than fluid simulations. We utilize a data-driven modeling approach to identify a red ...

American Institute of Physics2017

Replicated microcellular aluminium structures for thermal management

Alexandros Athanasiou-Ioannou

Open-pore aluminium foams are of interest in thermal management of power electronics due to their large specific surface area, low weight and relatively high thermal conductivity. The replication process is a low-cost and simple foam manufacturing method t ...

EPFL2017

Experimental evaluation of the thermal performances of a thermosyphon cooling system rejecting heat by natural and forced convection

John Richard Thome, Filippo Cataldo

In the present paper, a closed-loop thermosyphon cooling system for power electronics has been developed and tested. The evaporator is a multi-microchannel heat sink designed for high heat fluxes. The power electronics module is emulated by four independen ...

Pergamon-Elsevier Science Ltd2017

Buoyant Turbulent Kinetic Energy Production in Steep-Slope Katabatic Flow

Marc Parlange, Chad Higgins, Holly Jayne Oldroyd, Eric Richard Pardyjak

We develop several critical concepts that should be considered when interpreting, modelling and designing future experiments for flows over sloping terrain. Vertical buoyancy fluxes in katabatic flows can be positive and a source of turbulent kinetic energ ...

Springer Verlag2016