Purpose

The purpose of this paper is to study the natural convection and radiation heat transfer inside Nonagon inclined cavity with variable heated source length, which contains a porous medium saturated with nanofluid in the presence of uniform heat generation or absorption under the effect of uniform magnetic field with variable direction. The shape factor of nano particles is taking account for the model of nanofluid.

Design/methodology/approach

This study is established in two-dimensional space. The 2D numerical study is effectuated with Comsol Multiphysics based on the on the finite element method. The 2D equation system is exposed on dimensionless form taking into account the boundary conditions.

Findings

Results obtained show that the convection heat transfer is ameliorated with the augmentation of heated source length. The convection heat transfer is enhanced by increasing Rayleigh, Darcy numbers and the heated source length; however, it is reduced by rising Hartmann number. The presence of radiation parameter lead to improve the convection heat transfer in the presence of both uniform heat generation/absorption. The average Nusselt number reaches a maximum for an inclination of cavity γ = 45° and a minimum for γ = 60°. Both the increase of the shape factor of nano particles and the solid fraction of nano particles improve the convection heat transfer.

Originality/value

Different studies have been realized to study the heat transfer inside cavity contains porous medium saturated with nanofluid under magnetic field effect. In this work, the Nonagon geometric of cavity studied has never been studied. In addition, the effect of radiation parameter with relation of the shape factor of nanoparticles in the presence of uniform heat generation/absorption on the heat transfer performance have never been investigated. Also, the effect of magnetic field direction with relation of the inclination cavity on heat transfer performance.

中文翻译：

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纳米流体在非角形倾斜腔内的自由对流和热辐射，该多孔介质在均匀热量产生/吸收的情况下包含受方向可变的磁场影响的多孔介质

目的

本文的目的是研究具有可变热源长度的Nonagon倾斜腔内部的自然对流和辐射传热，该腔包含在纳米多孔流体中饱和的多孔介质，在均匀磁场的作用下，在均匀的热量产生或吸收的情况下，方向可变。纳米颗粒的形状因子考虑了纳米流体的模型。

设计/方法/方法

这项研究是建立在二维空间中的。基于有限元方法的Comsol Multiphysics进行了2D数值研究。考虑到边界条件，二维方程系统以无量纲形式公开。

发现

获得的结果表明，随着热源长度的增加，对流换热得到改善。对流换热通过增加瑞利，达西数和加热源的长度来增强。但是，随着Hartmann数的增加，它减少了。辐射参数的存在导致在均匀热量产生/吸收均存在的情况下改善对流传热。平均努塞尔数在腔γ= 45°的倾斜度时达到最大值，而在γ= 60°的倾斜度时达到最小值。纳米颗粒形状因子的增加和纳米颗粒的固体分数均改善了对流传热。

创意/价值

已经进行了不同的研究来研究在磁场作用下腔内的热传导包含纳米流体饱和的多孔介质。在这项工作中，从未研究过腔的Nonagon几何。另外，从未研究在均匀热量产生/吸收的情况下辐射参数与纳米颗粒的形状因子的关系对传热性能的影响。而且，磁场方向与倾斜腔的关系对传热性能的影响。