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MiR@W day: Multiscale Modelling Approach to Fluid Flows Involving Phase Change

Friday 20th July 2018

Organisers: Livio Gibelli (School of Engineering), Anirudh Rana (Mathematics Institute, Institute of Advanced Study)

Location: B3.02 Mathematics Institute, Zeeman Building, University of Warwick, Coventry CV4 7AL, UK


Evaporation and condensation processes are both of practical signicance in engineering and of fundamental interest in the pure sciences. These processes span over a wide range of time and length scales, and the challenge of dealing with their multiscale nature is the core motivation of this workshop. Leading experts in the field of phase change processes at different modelling scales, such as, microscopic (e.g., molecular dynamics), mesoscopic (e.g., kinetic theory) and macroscopic (e.g., fluid dynamics) will be brought together to present the state of the art in simulation and modelling and to identify possible new pathways.

This workshop may be of interest to the students/scholars working in area of computational and theoretical fluid dynamics.

Invited speakers

Title: A Numerical Study of Temperature Jumps in Evaporation of Water

Abstract: In 1999, Fang and Ward published a paper reporting measurements of large temperature jumps at the vapor-liquid interface, during the slow evaporation of purified water [1]. Temperature jumps in evaporation flows have also been observed in experiments adopting different setups [2]. The observed temperature jumps appeared as anomalous in that the vapor temperature, in proximity of the interface was found to be a few degrees higher than the liquid surface temperature, whereas it was expected to be slightly lower because of the vapor expansion in the evaporation flow. As pointed out in a few following papers [2], such expectation is not correct, in principle, since the heat flux also contributes to the interfacial temperature jump. The aim of the present work is to benchmark kinetic theory prediction of temperature jumps at the vapor-liquid interface of water, improving previous investigations neglecting molecular internal degrees of freedom and adopting unnecessary approximations on the Knudsen layer structure. The Direct Simulation Monte Carlo (DSMC) is adopted to simulate water vapor in contact with its liquid phase. The companion VSS collision model correctly reproduces water vapor transport properties. A proper setting of kinetic boundary conditions allows reproducing the experimental jumps reported in Refs [1,2].
However, the matching between theory and experiments requires assuming very low values of the evaporation coefficient. Hence, DSMC simulations are also used to estimate the possible corrections to be made on experimental temperature data, based on micro-thermocouples measurements, as pointed out in Ref. [3].
[1] G. Fang , C.A.Ward, Physical Review E, 59, 417-428 (1999)
[2] V. Badam, V. Kumar, F. Durst and K. Danov, Experimental Thermal and Fluid Science, 32, 276-292 (2007)
[3] M.A. Kazemi, D.S. Nobes, and J.A.W. Elliott, Langmuir, 33, 7169-7180 (2017)

Title: Moment equations from the Enskog-Vlasov equation

Title: Droplet heating and evaporation: hydrodynamic, kinetic and molecular dynamic modelling

Abstract: Some recently developed approaches to the hydrodynamic, kinetic and molecular dynamic modelling of mono and multi-component droplet heating and evaporation are discussed. New approaches to taking into account the effect of the moving interface during droplet evaporation on droplet heating for mono- and multi-component droplets are summarised. Simplified models for multi-component droplet heating and evaporation, based on the analytical solutions to the species diffusion equation inside droplets, are described. A multi-dimensional quasi-discrete model for heating and evaporation of complex multi-component hydrocarbon fuel droplets, and its application to modelling the heating and evaporation of realistic Diesel and gasoline fuel droplets are described. Recent developments of kinetic algorithms, including those taking into account the effect of inelastic collisions between molecules, are reviewed. The results of applications of molecular dynamics and quantum-chemical simulations to study the evaporation of n-dodecane droplets are described.


Aerial photograph of Maths Houses

See also:
Mathematics Research Centre
Mathematical Interdisciplinary Research at Warwick (MIR@W)
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Mathematics Research Centre
Zeeman Building
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