Islam Tarikul, Parveen N, Nasrin R
Department of Mathematics, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh.
Department of Mathematics, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj-8100, Bangladesh.
Heliyon. 2022 Mar 1;8(3):e09015. doi: 10.1016/j.heliyon.2022.e09015. eCollection 2022 Mar.
The mathematical modeling of two-dimensional unsteady free convective flow and thermal transport inside a half-moon shaped domain charged in the presence of uniform/non-uniform temperature and magnetic effects with Brownian motion of the nanoparticles has been conducted. Thirty-two types of nanofluids in a combination of various nanoparticles and base fluids having different sizes, shapes, and solid concentrations of nanoparticles are chosen to examine the better performance of heat transfer. The circular boundary is cooled while the diameter boundary is heated with uniform/non-uniform temperature. An external uniform/non-uniform/periodic magnetic field is imposed along diameter. The powerful partial differential equations solver, finite element method of Galerkin type, has been engaged in numerical simulation. The numerical solution's heat transfer mechanism reaches a steady state from the unsteady situation within a very short dimensionless time of about 0.65. The thermal transport rate enhances for increasing buoyancy force whereas decreases with higher magnetic intensity. The uniform thermal condition along the diameter of half-moon gives a higher thermal transport rate compared to non-uniform heating conditions. The non-uniform magnetic field provides greater values of the mean Nusselt number than the uniform field. In addition, the outcomes also predict that a better rate of temperature transport for kerosene-based nanofluid than water-based, ethylene glycol-based, and engine oil-based nanofluid. The heat transfer rate is observed at about 67.86 and 23.78% using Co-Kerosene and Co-water nanofluids, respectively, with an additional 1% nanoparticles volume fraction. The blade shape nanoparticles provide a better heat transfer rate than spherical, cylindrical, brick, and platelet shapes. Small size nanoparticles confirm a higher value of average Nusselt number than big size. Mean Nusselt number increases 22.1 and 5.4% using 1% concentrated Cu-water and Cu-engine oil nanofluid, respectively than base fluid.
对存在均匀/非均匀温度和磁效应且纳米颗粒有布朗运动的半月形区域内的二维非稳态自由对流流动和热传输进行了数学建模。选择了由各种纳米颗粒和具有不同尺寸、形状及纳米颗粒固体浓度的基础流体组合而成的32种纳米流体,以研究更好的传热性能。圆形边界被冷却,而直径边界以均匀/非均匀温度加热。沿直径施加外部均匀/非均匀/周期性磁场。采用强大的偏微分方程求解器——伽辽金型有限元法进行数值模拟。数值解的传热机制在约0.65的非常短的无量纲时间内从非稳态达到稳态。热传输速率随浮力增加而提高,随磁场强度增加而降低。与非均匀加热条件相比,半月形直径上的均匀热条件给出更高的热传输速率。非均匀磁场提供的平均努塞尔数比均匀磁场的值更大。此外,结果还预测,基于煤油的纳米流体的温度传输速率比基于水、乙二醇和发动机油的纳米流体更好。使用钴-煤油和钴-水纳米流体,在纳米颗粒体积分数额外增加1%时,传热速率分别约为67.86%和23.78%。叶片形状的纳米颗粒比球形、圆柱形、砖形和片状形状的纳米颗粒提供更好的传热速率。小尺寸纳米颗粒的平均努塞尔数比大尺寸纳米颗粒的值更高。使用1%浓度的铜-水和铜-发动机油纳米流体时,平均努塞尔数分别比基础流体增加22.1%和5.4%。