بررسی اثرات نسبت چگالی بر عملکرد مدل شبه‌پتانسیل در شبیه سازی جریان‌های چندفازی

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده مهندسی مکانیک، دانشگاه صنعتی اصفهان، اصفهان، ایران

چکیده

در این پژوهش، قابلیت و عملکرد مدل توسعه‌یافته‌ شبه‌پتانسیل شان – چن برای شبیه‌سازی جریان‌های چندفازی در نسبت چگالی بالا مورد ارزیابی قرار گرفته است. این مدل در نرم افزار آزاد و متن‌باز پالابوس که جریان سیال را با استفاده از روش شبکه بولتزمن شبیه‌سازی می کند پیاده‌سازی شده است. برای این منظور چندین مساله رایج از جمله آزمون لاپلاس، جدایی فازها، به هم آمیختگی دو حباب، برخورد قطره با سطح جامد و مایع مورد تحقیق قرار گرفته‌اند. بر اساس آزمون لاپلاس این مدل قابلیت تعیین مقادیر مختلف کشش سطحی در نسبت چگالی‌های مختلف را دارد. همچنین این مدل می‌تواند جدایی خودکار فازها و شکل سطح مشترک را بخوبی پیش‌بینی نماید. البته سرعت همگرایی حل با افزایش نسبت چگالی کاهش می‌یابد. شبیه‌سازی اختلاط دو حباب دو مورد از ضعف‌های عمده‌ این مدل که جریان پارازیتی بزرگ و نوسانات سطح مشترک در نسبت چگالی بالا است را آشکار می‌سازد. در شبیه‌سازی برخورد قطره با سطح جامد، تاثیر نسبت چگالی که باعث تغییر در عدد وبر نیز می‌شود بررسی شده است. با کاهش کشش سطحی و افزایش عدد وبر (در اعداد رینولدز یکسان) مقدار بیشینه پخش قطره بر روی سطح بیشتر ولی حرکت نوسانی آن کاهش می‌یابد. در نهایت نتایج شبیه‌سازی فرایند پاشش نشان می‌دهند که عدد وبر اثرات قابل توجهی در جدایی بخشی از لایه‌ی تاجی شکل دارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of Density Ratio Effects on Performance of the Pseudo-Potential Model in Multiphase Flows Simulation

نویسندگان [English]

  • S. M. Khatoonabadi
  • M. Ashrafizaadeh
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
چکیده [English]

In this research, the performance and capability of the developed pseudo-potential Shan- Chen model for the simulation of multiphase flows with large density ratios are evaluated. This model is applied in the Palabos open source software which simulates fluid flows by means of the Lattice Boltzmann method. For this reason, some well-known multiphase benchmarks are investigated such as the Laplace law, the segregation, the bubbles coalescence and the droplet impact with solid and liquid surfaces. According to the Laplace law, this model is capable of determining a wide range of surface tensions in different density ratios. In addition, this model is able to predict the interface shape and phase segregation automatically very well. However convergence rate is reduced as the density ratio increases. The simulation of two bubbles coalescence reveals that large spurious current and large interface oscillation are the two main drawbacks of the pseudo-potential model. In the droplet impact with a solid surface simulation, the effects of density ratio which leads to a difference in the surface tension and the Weber number are considered. When the Weber number is increased, the maximum spread increases but its vacillation decreases. Ultimately, the results of the splash process show that the Weber number has a remarkable influence on the breaking of a part of the crown layer.

کلیدواژه‌ها [English]

  • Shan-Chen model
  • Pseudo-potential model
  • Multiphase flows
  • Density ratio
  • Interface oscillation
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