دانشگاه صنعتی امیرکبیر نشریه مهندسی مکانیک امیرکبیر 2008-6032 50 2 2018 06 22 Investigation of the Effect of Velocity Slip and Temperature Jump on the Heat Transfer of Nanofluid in a Microchannel Under Constant Heat Flux with Lattice Boltzmann Method بررسی اثر لغزش سرعت و پرش دما بر انتقال حرارت نانوسیال در میکروکانالی تحت شار حرارتی ثابت با روش شبکه ی بولتزمن 255 270 857 10.22060/mej.2016.857 FA محمد کلته دانشکده مهندسی مکانیک، دانشگاه گیلان، رشت، ایران 0000-0003-3965-3749 علی علی پور لالمی دانشکده مهندسی مکانیک، دانشگاه گیلان، رشت، ایران Journal Article 2016 07 27 In this article, the effect of velocity slip and temperature jump on the flow and heat transfer characteristics of Al2O3 – Water nanofluid in a microchannel with insulated upper wall and constant heat flux on the lower one, is investigated using the lattice Boltzmann method. The problem is solved at Re equal to 5, for base fluid and nanofluid with 0.02 and 0.04 volume fractions, no-slip and slip conditions with 0.04 and 0.1 slip coefficients and also at 5 to 50 nm nanoparticle diameters. The results show that, in general, using the hydrophobic surfaces in addition to making a considerable reduction in wall shear stress, somewhat increases the heat transfer efficacy at uniform wall heat flux condition that can not be seen in the constant wall temperature situations. Also, it is shown that the effect of temperature jump on the average Nusselt number, is more for base fluid than the nanofluid and increases for higher slip coefficients. For nanofluid with 0.04 volume fraction, the average Nusselt number increases continuously with slip coefficient but, for base liquid, firstly it increases and then decreases. <span lang="AR-SA" dir="RTL">در</span><span lang="AR-SA"> <span dir="RTL">این</span> <span dir="RTL">مقاله</span> <span dir="RTL">اثر</span> <span dir="RTL">لغزش</span> <span dir="RTL">سرعت</span> <span dir="RTL">و</span> <span dir="RTL">پرش</span> <span dir="RTL">دما</span> <span dir="RTL">بر</span> <span dir="RTL">مشخصه</span> <span dir="RTL">های</span> <span dir="RTL">جریان</span> <span dir="RTL">و</span> <span dir="RTL">انتقال</span> <span dir="RTL">حرارتی</span> <span dir="RTL">نانوسیال</span> <span dir="RTL">آب</span></span><span> - <span lang="AR-SA" dir="RTL">آلومینا</span><span lang="AR-SA"> <span dir="RTL">در</span> <span dir="RTL">یک میکروکانال</span> <span dir="RTL">دو</span> <span dir="RTL">بعدی</span> <span dir="RTL">که</span> <span dir="RTL">در</span> <span dir="RTL">صفحه</span> <span dir="RTL">پایین</span> <span dir="RTL">تحت</span> <span dir="RTL">شار</span> <span dir="RTL">حرارتی</span> <span dir="RTL">ثابت</span> <span dir="RTL">و</span> <span dir="RTL">در</span> <span dir="RTL">صفحه</span> <span dir="RTL">ی</span> <span dir="RTL">بالا</span> <span dir="RTL">عایق</span> <span dir="RTL">است،</span> <span dir="RTL">با</span> <span dir="RTL">روش</span> <span dir="RTL">شبکه</span> <span dir="RTL">ی</span> <span dir="RTL">بولتزمن مورد</span> <span dir="RTL">مطالعه</span> <span dir="RTL">قرار</span> <span dir="RTL">گرفته</span> <span dir="RTL">است</span></span>. <span lang="AR-SA" dir="RTL">مساله</span><span lang="AR-SA"> <span dir="RTL">مورد</span> <span dir="RTL">نظر</span> <span dir="RTL">در</span> <span dir="RTL">عدد</span> <span dir="RTL">رینولدز</span></span> 5<span lang="AR-SA" dir="RTL">،</span><span lang="AR-SA"> <span dir="RTL">برای</span> <span dir="RTL">سیال</span> <span dir="RTL">پایه</span> <span dir="RTL">و</span> <span dir="RTL">نانو</span> <span dir="RTL">سیال</span> <span dir="RTL">با</span> <span dir="RTL">کسر</span> <span dir="RTL">حجمی</span></span> 02 / 0 <span lang="AR-SA" dir="RTL">و</span> 04 / 0 <span lang="AR-SA" dir="RTL">در شرایط</span><span lang="AR-SA"> <span dir="RTL">عدم</span> <span dir="RTL">لغزش</span> <span dir="RTL">و</span> <span dir="RTL">در</span> <span dir="RTL">ضرایب</span> <span dir="RTL">لغزش</span></span> 04 / 0 <span lang="AR-SA" dir="RTL">و</span> 1/ 0 <span lang="AR-SA" dir="RTL">و</span><span lang="AR-SA"> <span dir="RTL">نیز</span> <span dir="RTL">در</span> <span dir="RTL">قطر</span> <span dir="RTL">های</span> <span dir="RTL">نانوذرات</span></span> 5 <span lang="AR-SA" dir="RTL">تا</span> 50 <span lang="AR-SA" dir="RTL">نانومتر</span><span lang="AR-SA"> <span dir="RTL">بررسی</span> <span dir="RTL">شده</span> <span dir="RTL">است</span></span>. <span lang="AR-SA" dir="RTL">نتایج</span><span lang="AR-SA"> <span dir="RTL">نشان داد</span> <span dir="RTL">که</span> <span dir="RTL">به</span> <span dir="RTL">طور</span> <span dir="RTL">کلی</span> <span dir="RTL">استفاده</span> <span dir="RTL">از</span> <span dir="RTL">سطوح</span> <span dir="RTL">آبگریز</span> <span dir="RTL">ضمن</span> <span dir="RTL">کاهش</span> <span dir="RTL">محسوس</span> <span dir="RTL">تنش</span> <span dir="RTL">برشی</span> <span dir="RTL">دیواره،</span> <span dir="RTL">در</span> <span dir="RTL">شرایط</span> <span dir="RTL">شار</span> <span dir="RTL">حرارتی</span> <span dir="RTL">ثابت</span> <span dir="RTL">بر</span> <span dir="RTL">خلاف شرایط</span> <span dir="RTL">دما</span> <span dir="RTL">ثابت</span> <span dir="RTL">نه</span> <span dir="RTL">تنها</span> <span dir="RTL">باعث</span> <span dir="RTL">کاهش</span> <span dir="RTL">بازدهی</span> <span dir="RTL">انتقال</span> <span dir="RTL">حرارتی</span> <span dir="RTL">میکروکانال</span> <span dir="RTL">نمی</span> <span dir="RTL">شود،</span> <span dir="RTL">بلکه</span> <span dir="RTL">تا</span> <span dir="RTL">حدودی</span> <span dir="RTL">بازدهی</span> <span dir="RTL">آن</span> <span dir="RTL">را</span> <span dir="RTL">افزایش</span> <span dir="RTL">می دهد</span></span>. <span lang="AR-SA" dir="RTL">همچنین</span><span lang="AR-SA"> <span dir="RTL">مشخص</span> <span dir="RTL">شد</span> <span dir="RTL">که</span> <span dir="RTL">اثر</span> <span dir="RTL">پرش</span> <span dir="RTL">دمایی</span> <span dir="RTL">بر</span> <span dir="RTL">عدد</span> <span dir="RTL">ناسلت</span> <span dir="RTL">میانگین،</span> <span dir="RTL">در</span> <span dir="RTL">سیال</span> <span dir="RTL">پایه</span> <span dir="RTL">بیشتر</span> <span dir="RTL">از</span> <span dir="RTL">نانوسیال</span> <span dir="RTL">است</span> <span dir="RTL">و</span> <span dir="RTL">با</span> <span dir="RTL">افزایش</span> <span dir="RTL">ضریب لغزش</span> <span dir="RTL">بیشتر</span> <span dir="RTL">می</span> <span dir="RTL">شود</span></span>. <span lang="AR-SA" dir="RTL">بطوریکه</span><span lang="AR-SA"> <span dir="RTL">در</span> <span dir="RTL">نانو</span> <span dir="RTL">سیال</span> <span dir="RTL">با</span> <span dir="RTL">کسر</span> <span dir="RTL">حجمی</span></span> 04 / 0<span lang="AR-SA" dir="RTL">،</span><span lang="AR-SA"> <span dir="RTL">با</span> <span dir="RTL">افزایش</span> <span dir="RTL">ضریب</span> <span dir="RTL">لغزش</span> <span dir="RTL">بی</span> <span dir="RTL">بعد،</span> <span dir="RTL">عدد</span> <span dir="RTL">ناسلت</span> <span dir="RTL">میانگین</span> <span dir="RTL">به صورت</span> <span dir="RTL">پیوسته</span> <span dir="RTL">افزایش</span> <span dir="RTL">پیدا</span> <span dir="RTL">می</span> <span dir="RTL">کند</span> <span dir="RTL">ولی</span> <span dir="RTL">در</span> <span dir="RTL">سیال</span> <span dir="RTL">پایه</span> <span dir="RTL">این</span> <span dir="RTL">روند</span> <span dir="RTL">ابتدا</span> <span dir="RTL">صعودی</span> <span dir="RTL">و</span> <span dir="RTL">سپس</span> <span dir="RTL">نزولی</span> <span dir="RTL">است</span></span>.</span> https://mej.aut.ac.ir/article_857_847cc55b7032108eee6dd897f3bca8a5.pdf