تاثیر شکل ذرات محیط متخلخل بر انتشارپذیری طولی: انتقال آلایندهها
محورهای موضوعی : مدیریت آب در مزرعه با هدف بهبود شاخص های مدیریتی آبیاری
1 - کارشناس ارشد مهندسی سازه های آبی، مربی، دانشکده کشاورزی مشگین شهر، دانشگاه محقق اردبیلی، اردبیل، ایران
کلید واژه: FEFLOW, منحنی رخنه, CXTFIT, روش سلف پتانسیل, شکل خاکدانه,
چکیده مقاله :
شکل ذرات محیط متخلخل تاثیر بسزایی بر روی جریان و مخصوصاً انتشارپذیری طولی آن دارد. در تحقیق حاضر، طی آزمایشهایی بر روی سه ستون خاک حاویذرات شکسته و تیزگوش ، ماسه بستر رودخانه و ذرات کروی، تاثیر شکل ذرات محیط متخلخل بر روی انتشارپذیری طولی مورد بررسی قرار گرفت. با تزریق جریان وآلاینده ) NaCl ( در پنج سطح سرعت، منحنی رخنه در پنج نقطه در طول جریان به روش سلف پتانسیل استخراج و ضمن شبیهسازی نتایج با نرم افزار FEFLOW ، و باحل تحلیلی معکوس با نرمافزار CXTFIT2 ، انتشارپذیری طولی تعیین گردید. نتایج آزمایشها نشان داد به ازای سرعت ثابت، محیط با ذرات کروی دارای انتشارپذیریطولی بیشتر از دو محیط دیگر و در خاکدانه ماسهای بیشتر از ذرات شکسته است که این امر میتواند به دلیل افزایش سطح تماس و همچنین پیچ و خم مسیر با خارجشدن ذرات از شکل کروی اتفاق افتد. با افزایش سرعت، انتشارپذیری طولی در هر سه محیط کاهش مییابد همچنین هر چه خاکدانهها به شکل کروی نزدیکتر باشندتاثیر عامل مقیاس بیشتر و با افزایش سرعت، کاهش انتشارپذیری طولی در این خاکدانهها کمتر خواهد بود.
One of the most challenging quantities in analyzing the transfer of contaminant in the porous medium is the determination of longitudinal dispersivity. In this research, the effects of the porous media particle shape on the longitudinal dispersivity were investigated by experiments on three column of soil (broken texture, river sand, spherical texture). Flow and contaminant (NaCl) were injected at five levels of velocities and the Breakthrough curve was extracted at five points along the column by Self-Potential Method, Then, by simulating the results with FEFLOW software and the inverse analysis with CXTFIT2 software, longitudinal dispersivity was determined. The results indicate that, for constant velocity, the medium with spherical texture has a longitudinal dispersivity greater than the other two medium and in the sandy medium it is more than the broken texture. This can be due to the increase in the contact surface as well as the path’s tortuosity, with the particle coming out of the spherical shape. With increasing velocity, the longitudinal dispersivity decreases in all three medium. Also, as the particles are closer to the spherical shape, the scale effect will be greater, and with increasing velocity, the decrease in the longitudinal dispersivity in these medium will be less.
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