Purpose

The study aims to investigate magnetohydrodynamics thermal convection energy transference and entropy production in an open chamber saturated with ferrofluid having an isothermal solid block.

Design/methodology/approach

Analysis of thermal convection phenomenon was performed for an open chamber saturated with a nanofluid having an isothermal solid unit placed inside the cavity with various aspect ratios. The left border temperature is kept at T_c. An external cooled nanofluid of fixed temperature T_c penetrates into the domain from the right open border. The nanofluid circulation is Newtonian, incompressible, and laminar. The uniform magnetic field of strength B at the tilted angle of γ is applied. The finite volume technique is used to work out the non-linear equations of liquid motion and energy transport. For Rayleigh number (Ra=1e+7), numerical simulations were executed for varying the solid volume fractions of the nanofluid (ϕ = 0.01–0.04), the aspect ratios of a solid body (A_s = 0.25–4), the Hartmann number (Ha = 0–100), the magnetic influence inclination angle (γ = 0–π/2) and the non-dimensional temperature drop (Ω = 0.001–0.1) on the liquid motion, heat transference and entropy production.

Findings

Numerical outcomes are demonstrated by using isolines of temperature and stream function, profiles of mean Nusselt number and entropy generations. The results indicate that the entropy generation rate and mean Nu can be decreased with an increase in Ha. The inner solid block of A_s = 0.25 reflects the maximum heat transfer rate in comparison with other considered blocks. The addition of nano-sized particles results in a growth of energy transport and mean entropy generations.

Originality/value

An efficient computational technique has been developed to solve natural convection problem for an open chamber. The originality of this research is to scrutinize the convective transport and entropy production in an open domain with inner body. The outcomes would benefit scientists and engineers to become familiar with the investigation of convective energy transference and entropy generation in open chambers with inner bodies, and the way to predict the energy transference strength in the advanced engineering systems.

中文翻译：

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在具有固体的方形开放室内纳米液体的 MHD 自由对流中的熵产生

目的

该研究旨在研究磁流体动力学热对流能量转移和熵产生在一个充满铁磁流体的开放室中，该铁磁流体具有等温固体块。

设计/方法/方法

对充满纳米流体的开放室进行热对流现象分析，纳米流体具有放置在具有不同纵横比的腔内的等温固体单元。左边界温度保持在T _c。固定温度T _c的外部冷却纳米流体从右侧开放边界渗透到域中。纳米流体循环是牛顿的、不可压缩的和层流的。γ倾角处强度为 B 的均匀磁场被申请;被应用。有限体积技术用于计算液体运动和能量传输的非线性方程。对于瑞利数（Ra = 1e + 7），执行数值模拟以改变纳米流体的固体体积分数（φ = 0.01-0.04），固体的纵横比（A _s  = 0.25-4），Hartmann数（Ha = 0-100），磁影响倾角（γ = 0-π/2）和无量纲温降（Ω = 0.001-0.1）对液体运动、传热和熵产生的影响。

发现

数值结果通过使用温度和流函数的等值线、平均努塞尔数和熵代分布来证明。结果表明，熵产生率和平均Nu可以随着Ha的增加而降低。_{A s} = 0.25的内部实体块 反映了与其他考虑的块相比的最大传热率。纳米尺寸粒子的添加导致能量传输和平均熵生成的增长。

原创性/价值

已经开发了一种有效的计算技术来解决开放室的自然对流问题。本研究的独创性在于用内部物体来审视开放域中的对流传输和熵产生。这些结果将有利于科学家和工程师熟悉在具有内部主体的开放式腔室中对对流能量传递和熵产生的研究，以及在先进工程系统中预测能量传递强度的方法。