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Concept

Forced convection

Publications associées (25)

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

Convection of water vapour in snowpacks

Michael Lehning, Varun Sharma, 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

Improved framework to estimate travel time and derived distributions in hydrological control volumes

Mitra Asadollahi

Crossing properties of soil saturation, defined as the duration and excursion of soil saturation below and above certain thresholds, are key variables to ecosystem functioning and evolution by primarily influencing the plant and soil microbes physiological ...

EPFL2022

Water vapor transport in snowpacks

Mahdi Jafari

This thesis is an in-depth treatment of water vapor transport in snowpacks and its impacts on snow structure. The aim is to better understand this transport process and to lay the basis for a model representation in physics-based multi-layer snow models. O ...

EPFL2022

A mechanistic assessment of urban heat island intensities and drivers across climates

Gabriele Manoli

The urban heat island effect (UHI) has been widely observed globally, causing climate, health, and energy impacts in cities. The UHI intensities have been found to largely depend on background climate and the properties of the urban fabric. Yet, a complete ...

2022

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

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

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

Accurate buoyancy and drag force models to predict particle segregation in vibrofluidized beds

Mehrdad Kiani Oshtorjani

The segregation of large intruders in an agitated granular system is of high practical relevance, yet the accurate modeling of the segregation (lift) force is challenging as a general formulation of a granular equivalent of a buoyancy force remains elusive ...

AMER PHYSICAL SOC2021

Direct numerical simulation of phase change in the presence of non-condensable gases

Lubomír Bures

This paper describes a new numerical method for the simulation of phase change phenomena between a liquid and a vapour in the presence of non-condensable gases. The method is based on an interface-tracking approach in the framework of single-fluid modellin ...

2020

Buoyancy-driven melting and solidification heat transfer analysis in encapsulated phase change materials

Sophia Haussener, Nithin Mallya

Controlled melting and solidification in encapsulated phase change materials (PCMs) is of practical interest, for example, in latent heat storage applications. The choice of PCMs and the dynamic heat transfer characteristics during phase change - affecting ...

2021

Invariant states in inclined layer convection. Part 1. Temporal transitions along dynamical connections between invariant states

Tobias Schneider, Florian Reetz

Thermal convection in an inclined layer between two parallel walls kept at different fixed temperatures is studied for fixed Prandtl number . Depending on the angle of inclination and the imposed temperature difference, the flow exhibits a large variety of ...

Cambridge University Press2020

The Impact of Diffusive Water Vapor Transport on Snow Profiles in Deep and Shallow Snow Covers and on Sea Ice

Varun Sharma, Michael Lehning, Nander Wever, Adrien Michel, Isabelle Amandine Gouttevin, Mahdi Jafari, Margaux Caroline Patricia Couttet

Water vapor transport has been highlighted as a critical process in Arctic snowpacks, shaping the snow cover structure in terms of density, thermal conductivity, and temperature profile among others. Here, we present an attempt to describe the thermally-in ...

2020

Convection in Lakes

Alfred Johny Wüest, Damien Bouffard

Lakes and other confined water bodies are not exposed to tides, and their wind forcing is usually much weaker compared to ocean basins and estuaries. Hence, convective processes are often the dominant drivers for shaping mixing and stratification structure ...

2019

Convection‐Diffusion Competition Within Mixed Layers of Stratified Natural Waters

Alfred Johny Wüest, Damien Bouffard, Oscar Rodrigo Sepúlveda Steiner

In stratified natural waters, convective processes tend to form nearly homogeneous mixed layers. However, shear‐driven turbulence generated by large‐scale background flow often rapidly smooths them through mixing with the stratified surroundings. Here we s ...

2019

Modeling and experimentation of conductive and radiative transfer through heterogeneous insulators in high-flux environments

Jérémy Raphaël Mora-Monteros

Heterogeneous materials are used in a wide range of applications involving high heat flux environments such as concentrated solar reactors, high-temperature furnaces, or thermal protection systems of space vehicles. The thermal response of heterogeneous ma ...

EPFL2019

Design and optimization of a high-temperature latent heat storage unit

Sophia Haussener, Ehsan Rezaei

High-temperature latent heat thermal energy storage systems offer compact storage solutions, benefiting from the large latent heat of phase change materials. Common challenges in their design process are the low thermal conductivity of the phase change mat ...

2019

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

Built-in, exposed or concealed comfort services. Attempts (incomplete) to industrialise collective housing after 1945

Giulia Marino

Simultaneous consideration of active devices – especially mechanical heating and ventilation – and passive devices – including insulation and waterproofing of building envelopes – was one of the most notable aspects of studies of the management of physiolo ...

CRC Press - Taylor & Francis Group2018

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

Ice-covered Lake Onega: effects of radiation on convection and internal waves

Alfred Johny Wüest, Damien Bouffard, Natacha Pasche

Early-spring under-ice convection in the Petrozavodsk Bay of Lake Onega (Russia) was investigated as part of an interdisciplinary research project conducted during March 2015. Measurements performed using a thermistor chain and vertical profiling sensors w ...

Springer Verlag2016