2.1. Problem Definition
Figure 1 illustrates the important geometric parameters of current geometry. Also sample mesh is presented. The inner and outer cylinders are considered as hot and cold walls, respectively. Horizontal magnetic field has been considered.
2.2. Governing Equation
2D steady convective flow of nanofluid in a porous media is considered in existence of constant magnetic field. The PDEs equations are:
(1)(2)(3)(4)
, 
and 
are defined as:
(5)(6)(7)(8)
are obtained according to Koo–Kleinstreuer–Li (KKL) model:
(9)(10)All required coefficients and properties are illustrated in Tables 1 and 2.
Vorticity and stream function should be used to eliminate pressure source terms:
(11)Introducing dimensionless quantities:
(12)The final formulae are:
(13)(14)(15) where dimensionless and constants parameters are defined as:
(16) and boundary conditions are:
on inner wall
on outer wall
on other walls
on all walls
(17)Local and average Nusselt over the hot wall can be calculated as:
(18)(19)