Numerical Study On Capillarity- Dominant Free Surface And Interfacial Flows

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Title: Numerical Study On Capillarity- Dominant Free Surface And Interfacial Flows
Author: Wang, Zhaoyuan
Abstract: The continuum surface force (CSF ) method has been extensively employed in the volume -of -fluid (VOF ) , level set (LS ) and front tracking methods to model surface tension forces . Its ability is limited for the surface tension dominant free surface and interfacial flows due to the existence of spurious currents . These currents may lead to disastrous interface instabilities and failure of grid convergence , which are present in all the previous versions of the CSF algorithm . In this study , a coupled level set and volume -of -fluid method (CLSVOF ) is employed for interface tracking , which offers more accurate computations of the curvature and the normal vector and excellent mass conservation properties . The surface tension is modeled by a new surface tension implementation algorithm , referred to as the pressure boundary method (PBM ) . The surface tension effect is incorporated into the Navier -Stokes equation via a capillary pressure gradient term in the first step of a two -step projection method . The accuracy and capability of the present algorithms are tested and validated by a series of numerical experiments carried out for both free surface and two -phase interfacial flows . The CLSVOF method demonstrates superiority over the VOF method in surface tension modeling . It has been shown that the PBM method drastically suppresses the spurious currents with the sharp pressure jump condition preserved . The robustness of the PBM method on interfacial flows with large density ratios has also been exhibited . The CLSVOF and PBM methods have been applied to study the pinch -off mechanism of a pendant droplet , the relaxation of an elongated liquid ligament and the dynamics of a gas bubble rising in a vertical tube . The results of the simulations are compared with data from the experimental and theoretical measurements available in the literature , and good agreement has been achieved . The accuracy , robustness and capability of the current numerical methods are further validated through these applications .
URI: http : / /hdl .handle .net /10106 /318
Date: 2007-08-23

Citation

Numerical Study On Capillarity- Dominant Free Surface And Interfacial Flows. Available electronically from http : / /hdl .handle .net /10106 /318 .

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