تأثیر نفوذپذیری و پخشیدگی مولکولی بر الگوی جریان همرفتی در محیط‌های متخلخل درز و شکاف‌دار

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری مهندسی منابع آب، دانشکدة مهندسی و فناوری کشاورزی، پردیس کشاورزی و منابع طبیعی دانشگاه تهران

2 استاد دانشکدة مهندسی و فناوری کشاورزی، پردیس کشاورزی و منابع طبیعی دانشگاه تهران

3 دانشیار دانشکدة علوم زمین، دانشگاه شهید بهشتی

چکیده

در این مقاله، اثر نفوذپذیری به‌منزلة مشخصه‌ای از محیط متخلخل و پخشیدگی مولکولی به‌منزلة خصوصیتی از املاح بر جریان همرفتی در محیط‌های متخلخل درز و شکاف‌دار، با استفاده از مدل‌سازی‌های عددی مطالعه شده است. مدل مفهومی به‌صورت محیطی متخلخل دارای درز و شکاف‌های منظم عمودی و افقی در نظر گرفته شده است. چهار سناریوی مدل‌سازی با مقادیر متفاوت نفوذپذیری ماتریکس متخلخل و ضریب پخشندگی  مولکولی در نظر گرفته شد. نتایج نشان می‌دهد با کاهش ضریب پخشندگی مولکولی، املاح به واسطة حرکت در درز و شکاف‌ها به عمق بیشتری از محیط متخلخل انتقال می‌یابند. همچنین، با افزایش نفوذپذیری ماتریکس متخلخل، سرعت جریان همرفتی افزایش و مقدار املاح بیشتری در محیط متخلخل جریان می‌یابد.
 

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Permeability and Molecular Diffusion Effects on Convective Flow Pattern in Fractured Porous Media

نویسندگان [English]

  • Marzieh Malmir 1
  • Majid Kholghi 2
  • Hamidreza Nassery 3
  • Abdolhossein Hoorfar 2
1 PhD Candidate, Water Resources Engineering, Faculty of Agricultural Engineering and Technology, University College of Agricultural and Natural Resources, University of Tehran
2 Professor, Faculty of Agricultural Engineering and Technology, University College of Agriculture and Natural Resources, University of Tehran
3 Associate Professor, Faculty of Earth Sciences, Shahid Beheshti University
چکیده [English]

Local differences in fluid density have important role in contaminant transport. Study of variable-density flow and solute transport in fractured porous media is necessary to figure out phenomena like contaminant transport of high density. In this research, the effect of permeability and molecular diffusion, respectively as a characteristic of porous medium and solute, on convective flow in fractured porous media has been studied using numerical modeling by FRAC3DVS/Hydro Geosphere (HGS) model. Conceptual model has been considered as a porous medium contained regular vertical and horizontal fractures. Four scenarios of different porous matrix permeability and free-solution diffusion coefficients have been taken account into the modelling process. The results indicated various patterns of solute transport in fractured porous medium in four different scenarios. So that, in the first one with high molecular diffusion coefficient, the solute is diffused into porous matrix from fractures symmetrically. While in the second scenario, with low molecular diffusion coefficient, the solute is transported in deeper depth and is diffused into porous matrix from fractures in an uprising way, in opposite direction of the contaminant entrance direction. In the next scenario, the more porous matrix permeability, the more convective flow velocity and solute transport in porous matrix. Finally, less differences between the matrix and fracture permeability in the last scenario leads to decrease of the fracture effects on the convective flow pattern, so that flow pattern in the fractured porous medium becomes similar to flow pattern in the homogenous porous medium.

کلیدواژه‌ها [English]

  • fractured porous media
  • density dependent flow and solute transport
  • convective flow
  • Numerical Modeling
  • FRAC3DVS/HydroGeoSphere (HGS) model

مراجع

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