توسعه یک حلگر کوپل تعقیب سطح فاصل برای حل عددی میدان جریان های دوفازی در اعداد رینولدز پایین در بستر foam-extend

در این پژوهش، برای اولین بار یک حلگر حجم محدود کوپل، برای حل عددی همزمان معادلات جریان سیال تراکم‌ناپذیر دوفازی در اعداد رینولدز پایین و معادله موقعیت سطح‌فاصل بین دوفاز با اعمال شروط مرزی روی سطح‌فاصل در بستر فوم اکستند توسعه می‌یابد. جریان‌های مورد مطالعه برای جابه‌جایی سطح و شبکه به‌صورت آرام، در محدوده اعداد رینولدز کمتر از 100 در نظر گرفته می‌شود. این حلگر، مبتنی بر الگوریتم تعقیب سطح‌فاصل می‌باشد که به‌کمک ترفند سلول با ضخامت صفر، پیاده‌سازی می‌شود. مزیت اصلی این حلگر در این است که تمامی معادلات حاکم بر هر دوفاز به‌وسیله سلول‌های مجاور سطح واصل با یکدیگر و با معادله موقعیت سطح‌فاصل کوپل شده و به‌صورت همزمان حل می‌گردند. عملکرد حلگر، با حل جریان درون مجرا و روی پله مورد ارزیابی قرار می‌گیرد و میرایی امواج ایجاد شده روی سطح‌فاصل و نحوه تغییر متغیرهای جریان مورد بررسی قرار خواهد گرفت. نتایج به‌دست آمده از حلگر پیشنهادی در مقایسه با سایر حلگرهای جریان ارائه شده در پژوهش‌های پیشین حاکی از تطبیق کامل نتایج حاصل است.

developing an interface tracking coupled solver for solving two phase flow fields at low reynolds numbers in foam-extend platform

in the present study, for the first time, a finite volume coupled solver is developed for the simultaneous numerical solving of two-phase incompressible fluid flow equations at low reynolds numbers, and for solving the the interface position equation by applying interface boundary conditions using the foam-extend platform. the studied flows with interface and mesh motion are considered to be laminar and in the range of reynolds numbers less than 100. the foam-extend is a fork of openfoam, an opensource object-oriented c++ library for computational continuum mechanics. this solver is based on the interface tracking algorithm, which is developed using an innovative technique called zero-thickness cell. this technique removes the distance effect for the cell adjacent to the interface, and the interface is modeled with zero thickness cells. the main advantage of the present coupled solver compared to the previously developed solvers is that in this solver, all the equations in both phases are coupled with each other by cells adjacent to the interface and with an the interface position equation. all the governing equations and the interface position equation are assembled in a single linear system of equations and simultaneously solved. in fact, unlike the usual segregated procedure of solving two phase flows, where the phases are solved with lagged value boundary conditions, in the present solver, the phases are solved simultaneously with the interface conditions in an implicit manner and in the same block matrix system. the movement of the interface was done separately, and in another step. for this purpose, the kinematic condition was implemented. the computational performance of the coupled solver was evaluated by solving the equations of two-phase fluid flow inside a channel and on a backward-facing step. in the beginning, a preliminary investigation was done for the case, where both phases were completely independent and decoupled. matching the interface with the streamlines, as well as the reasonable and justifiable movement of the surface, has been observed from the physical point of view. also, the damping of the numerical oscillations generated on the interface and changing the flow variables will be investigated. the present results are in excellent agreement with other results reported in the literature.