An experimental and numerical study of droplet spreading and imbibition on microporous membranes

2021 ◽  
Vol 615 ◽  
pp. 126191
Author(s):  
Debanik Bhattacharjee ◽  
Hadi Nazaripoor ◽  
Babak Soltannia ◽  
Md Farhad Ismail ◽  
Mohtada Sadrzadeh
Keyword(s):  
Numerical Study ◽  
Microporous Membranes ◽  
Droplet Spreading

Numerical Study on Substrate Remelting, Flow, and Resolidification in Microcasting

Volume 3 ◽  
2004 ◽  
Author(s):  
F. J. Hong ◽  
H.-H. Qiu
Keyword(s):  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Numerical Study ◽  
Thermal Contact ◽  
Spreading Factor ◽  
Droplet Spreading ◽  
Molten Droplet ◽  
Front Shape ◽  
Complex Fluid

A large and highly superheated molten droplet impacting onto the substrate during the microcasting was studied numerically. In this study, same material for both the droplet and the substrate was considered. Numerical model including the complex fluid dynamics of droplet, interfacial thermal contact resistance, and substrate remelting, as well as the flow in the substrate has been developed. Numerical simulations of a microcasting experiment were conducted with the different thermal contact resistances. The results of simulations show that the spreading factor and substrate remelting agreed well with the experimental data under the assumption of an appropriate thermal contact resistance. It is also found that the thermal contact resistance plays an important role not only in droplet spreading arrest but also in the determination of substrate remelting volume and remelting front shape. The effects of droplet impacting velocity, superheat and substrate temperature were also investigated.

scholarly journals Numerical study of the spreading and solidification of a molten particle impacting onto a rigid substrate under plasma spraying conditions

2015 ◽  
Vol 19 (1) ◽  
pp. 277-284 ◽  
Author(s):  
Soufiane Oukach ◽  
Hassan Hamdi ◽  
Ganaoui el ◽  
Bernard Pateyron
Keyword(s):  
Reynolds Number ◽  
Plasma Spraying ◽  
Numerical Study ◽  
Thermal Contact ◽  
Droplet Spreading ◽  
Wide Range ◽  
Element Approach ◽  
Molten Particle ◽  
Spread Factor ◽  
Surface Tension Forces

This paper deals with simulation of the spreading and solidification of a fully molten particle impacting onto a preheated substrate under traditional plasma spraying conditions. The multiphase problem governing equations of mass, momentum and energy conservation taking into account heat transfer by conduction, convection and phase change are solved by using a Finite Element approach. The interface between molten particle and surrounding air, is tracked using the Level Set method. The effect of the Reynolds number on the droplet spreading and solidification, using a wide range of impact velocities (40-250m/s), is reported. A new correlation that predicts the final spread factor of splat as a function of Reynolds number is obtained. Thermal contact resistance, viscous dissipation, wettability and surface tension forces effects are taken into account.

Numerical study of the melting and resolidification of the substrate during the impact of a ceramic droplet in a plasma spraying process

2019 ◽  
Vol 88 (2) ◽  
pp. 20901 ◽  
Author(s):  
Mouloud Driouche ◽  
Tahar Rezoug ◽  
Mohammed El Ganaoui
Keyword(s):  
Numerical Model ◽  
Phase Change ◽  
Solid Phase ◽  
Numerical Study ◽  
Solid Substrate ◽  
Navier Stokes ◽  
Droplet Spreading ◽  
Substrate Melting ◽  
Volume Method ◽  
The Impact

The substrate melting can significantly improve the properties of plasma spray coatings. Indeed the adhesion of the projected particles to the substrate can be ameliorated by the substrate melting. In this article, a numerical model is developed to study the dynamics of fluids and heat transfer with liquid/solid phase change during impact of a fully melted alumina particle on an aluminum solid substrate, taking into account of the substrate melting. The model is based on solving the Navier-Stokes and energy equations with liquid / solid phase change. These equations are coupled with the fluid of volume method (VOF), to follow the free surface of the particle during its spreading and solidification. The finite volume method is used to discretize the equations in a 2D axisymmetric domain. A comparison with the published experimental results was carried out to validate this numerical model. Simulations were performed for different initial droplet diameters to study its effect on droplet spreading as well as on substrate melting. It has been observed that the substrate melting begins before the droplet spreads completely; the substrate melting reaches its maximum when the droplet is close to its total solidification. Droplet spreading and substrate melting are more important for large sizes droplets.

Droplet spreading and capillary imbibition in a porous medium: A coupled IB-VOF method based numerical study

2018 ◽  
Vol 30 (1) ◽  
pp. 012112 ◽  
Author(s):  
Saurish Das ◽  
H. V. Patel ◽  
E. Milacic ◽  
N. G. Deen ◽  
J. A. M. Kuipers
Keyword(s):  
Porous Medium ◽  
Numerical Study ◽  
Vof Method ◽  
Capillary Imbibition ◽  
Droplet Spreading

scholarly journals Experimental and numerical study on sensible heat transfer at droplet/wall interactions

2017 ◽  
Author(s):  
Ana Sofia Moita ◽  
Emanuele Teodori ◽  
Pedro Pontes ◽  
António Luís Nobre Moreira ◽  
Anastasios Georgoulas ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
High Speed ◽  
Numerical Study ◽  
Temperature Fields ◽  
Sensible Heat ◽  
Droplet Spreading ◽  
The Impact

The present study addresses a detailed experimental and numerical investigation on the impact of water dropletson smooth heated surfaces. High-speed infrared thermography is combined with high-speed imaging to couple the heat transfer and fluid dynamic processes occurring at droplet impact. Droplet spreading (e.g. spreading ratio) and detailed surface temperature fields are then evaluated in time and compared with the numerically predicted results. The numerical reproduction of the phenomena was conducted using an enhanced version of a VOF- based solver of OpenFOAM previously developed, which was further modified to account for conjugate heat transfer between the solid and fluid domains, focusing only on the sensible heat removed during  droplet spreading. An excellent agreement is observed between the temporal evolution of the experimentally measured and the numerically predicted spreading factors (differences between the experimental and numerical values were always lower than 3.4%). The numerical and experimental dimensionless surface temperature profiles along the droplet radius were also in good agreement, depicting a maximum difference of 0.19. Deeper analysis coupling fluid dynamics and heat transfer processes was also performed, evidencing a strong correlation between maximum and minimum temperature values and heat transfer coefficients with the vorticity fields in the lamella, which lead to particular mixing processes in the boundary layer region. The correlation between the resulted temperature fields and the droplet dynamics was obtained by assuming a relation between the vorticity and the local heat transfer coefficient, in the first fluid cell i.e. near the liquid-solid interface. The two measured fields revealed that local maxima and minima in the vorticity corresponded to spatially shifted local minima and maxima in the heat transfer coefficient, at all stages of the droplet spreading. This was particularly clear in the rim region,which therefore should be considered in future droplet spreading models.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.5024

scholarly journals Droplet impact onto an elastic plate: a new mechanism for splashing

2018 ◽  
Vol 839 ◽  
pp. 561-593 ◽  
Author(s):  
Michael Pegg ◽  
Richard Purvis ◽  
Alexander Korobkin
Keyword(s):  
Surface Roughness ◽  
Numerical Methods ◽  
Blow Up ◽  
Numerical Study ◽  
Flexible Substrate ◽  
Normal Modes ◽  
Rigid Wall ◽  
Droplet Impact ◽  
Rigid Substrate ◽  
Droplet Spreading

During a droplet impact onto a substrate, splashing is known to be caused by the presence of surrounding gas or by surface roughness. Impact occurring in a vacuum onto a smooth rigid wall results in droplet spreading, rather than development of a corona or prompt splash. Here we present an analytical and numerical study of a third potential splashing mechanism, namely elastic deformation of the substrate. An axisymmetric Wagner-style model of droplet impact is formulated and solved using the method of normal modes, together with asymptotic analysis and numerical methods. We highlight the effect that a flexible substrate brings to the contact line velocity and jet behaviour, demonstrating that oscillation of the substrate can cause blow-up of the splash jet which is absent for a rigid substrate and indicate the onset of splashing.

The Numerical Study of a Dropwise Condensation Mode when Cooling Heat Transfer Surfaces

2016 ◽  
Vol 685 ◽  
pp. 244-250 ◽  
Author(s):  
Alexander V. Krainov ◽  
E.N. Pashkov ◽  
Roman E. Lushnikov ◽  
Vladimir A. Arkhipov
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Setting Time ◽  
Droplet Surface ◽  
Stationary Mode ◽  
Temperature Profiles ◽  
Two Dimensional ◽  
Droplet Spreading ◽  
Simple Geometry ◽  
Condensation Mode

A two-dimensional nonstationary model of calculation of heat transfer at viscous fluid droplet spreading over the heated substrate is presented. A process of the fixed droplet spreading over a simple geometry substrate has been calculated. A hydrodynamic picture of the process of spreading has been obtained. The influence of the parameters of the model on the nature of spreading has been studied. The temperature profiles at the droplet surface have been obtained. The setting time of the stationary mode has been evaluated.

Retention of Liquids Above Microporous Membranes

2003 ◽  
Vol 790 ◽  
Author(s):  
John Charkoudian ◽  
Volkmar Thom
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Surface Modification ◽  
High Throughput ◽  
Liquid Surface ◽  
Polymer Surface ◽  
Microporous Membranes ◽  
Droplet Spreading ◽  
Liquid Surface Tension ◽  
Multiwell Plates

ABSTRACTThe ability of membranes to retain fluids without leaking in devices such as high throughput multiwell plates was examined as a function of membrane polymer, surface modification, and liquid surface tension. Microporous membranes (200–800nm) act as arrays of millions of imperfect microcapillaries. Extrusion and leaking requires pressure plus coalescence of microdroplets. For unmodified membranes, the liquid hold up height (pressure) is critically dependent on liquid surface tension, rising rapidly when the contact angle prevents droplet spreading and coalescence. Topography, as measured by AFM, also plays a role in ease of coalescence. Surface modification has a large impact on hold up pressure and its dependence on liquid surface tension.

Numerical study of the low-frequency atomic dynamics in a Lennard-Jones glass

1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,
Keyword(s):  
Numerical Study ◽  
Low Frequency ◽  
Lennard Jones
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