Abstract
The mixed convection flow of the nano–encapsulated phase change materials (NEPCM) plays an efficient role for the enrichment of heat transfer in thermal systems. So, this paper aims to examine the unsteady mixed convection due to various types of inner/outer movements within porous enclosures. The inner movement is a rotation of an inner cylinder and three cases are considered based on the direction of the rotation, namely, clockwise rotation, fixed cylinder and anticlockwise rotation. The outer movement is a lid-driven wall of the geometry. Various thermal cases of the inner cylinder are taken into account, namely, hot, adiabatic and cold rotating cylinders. The finite element method (FEM) based on CBS algorithm are applied to solve the governing equations. The main results disclosed that the rotation modes of the inner cylinder give various configurations of the circulation nanofluid flow and cause a high forced convection. Also, variety of the thermal conditions of the rotating cylinder can be considered as important factors for examining rate of the heat transfer. Furthermore, in case of the clockwise rotation, the range of the Reynolds number (10 ≤ Re ≤ 1000) causes a reduction in values of the stream function up to 37%.