**1. Introduction**

Fluids, generally, have a major role in many problems related to industrial and engineering applications like crystal growing, glass blowing, polymer extrusion processes, metallurgical processes, and so on. In the extrusion process, the heated liquid stretching into a cooling system, as well as the phenomenon in which the tiny sized particles are transferred from a hot surface to a cool surface, is called thermophoresis. In gasses, tiny particles like dust exert force parallel to the temperature gradient called thermophoretic force, and the motion gained by these particles is known as thermophoretic velocity. In thermophoresis, tiny particles are transferred towards cold surfaces, whereas hot surface particles also resist taking place and, as a result, a particle free layer is observed around the hot surface, as analyzed by Goldsmith and May [1]. The most important application of this phenomenon is to remove tiny particles from the path of gas particles used in turbine blades. The same phenomenon was used by Goren [2] in the study of aerosol particles, and this idea was extended by Jayaraj et al. [3] in the natural convection. The idea of mass transfer in this phenomenon was investigated by Selim et al. [4]. They analyzed the effects of physical parameters involved in the model. Chamka et al. [5,6] observed the thermophoresis effect in free convection boundary layer flow over

the permeable wall. Das [7] studied variable fluid properties with slip boundary conditions. Flow in porous media is highly important in enhanced oil recovery, geothermal energy extraction, insulation of buildings, food processing, heat storage beds, composite manufacturing, and the coating of paper and textile processes. Porous media flow describes different practical and engineering applications like oil or gaseous movement, liquid in the oil reservoir or gaseous field, the purification process of oil, gaseous wells, drilling, and the processing of carbon made substances and cosmetic material.

Generally, the study of non-Newtonian fluid flow in two- and three-dimensional problems is a tough job because of its high nonlinearity and, especially, the addition of extra terminologies such as magnetic field, porous medium, thermophoretic term, dissipation term, and so on. Despite these difficulties, efforts are being made by the researchers to solve such problems. The idea of viscous dissipation and permeable media was introduced by Al-Hadrami et al. [8]. In another paper, Al-Hadrami et al. [9] studied the combined problem of convection for both forced and free convection through a permeable channel. The micropolar fluids in two and three dimensions belong to the non-Newtonian fluids explained by Łukaszewicz [10] in his book. It is pointed out that the Navier-Stokes equation is not sufficient to handle the Cauchy stress tensor of micropolar fluid and, therefore, this fluid belongs to non-Newtonian fluids. Aouadi [11] presented a numerical solution for micropolar liquid flow over a stretched plate. The flow of second grade fluid with heat flux over a stretching surface is described in the studies of Chauhan and Olkha [12] and Cortell [13]. Dandapat and Gupta [14] observed the allied problem over a stretching sheet with some modification. The time-dependent motion of second order liquid in partially filled porous media was explored by Chuhan and Kumar [15]. Khan and Shafie [16] studied the generalized Burger's fluid including rotation in a porous medium. They observed effects of embedded parameters related to the model. Micropolar fluid is one of the important sub-class of non-Newtonian fluid. Studies related to micropolar fluids with various physical configurations with thermal radiation were presented by Abo-Eldahab and Ghonaim [17], Rashidi et al. [18,19], Heydari et al. [20], and Tripathy et al. [21]. The idea of heat and mass transfer mechanisms were described by the researchers to study the impact of various embedded parameters on the nanoparticle volume fraction. Rahman and Sattar [22] and Bakr [23] have studied the heat and mass transfer flow of micropolar fluid using the oscillatory boundary conditions. Ramzan et al. [24] have examined the Buoyancy impacts on the heat and mass transfer flow of the micropolar fluid with double stratification. Srinivasacharya and Ramreddy [25] have inspected the heat and mass transfer in micropolar fluid with thermal and mass stratification.

Recently, thin film flow has been an important subject of research. Thin film fluid is used for making different heat exchangers and tools in chemical techniques, and these applications require complete comprehension on the motion procedure. The applications comprise wire and fiber coating, polymer preparing, and so on. This motion is attached to manufacturing various types of sheets, either metallic or plastic. The quality of the final product is related to heat and mass transport and the rate of stretching. An analysis of heat transfer in Williamson nanofluid flow was conducted by Nadeem and Hussain [26] and Khan et al. [27]. Aziz et al. [28] studied heat transfer through thin film flow on an unsteady stretching sheet with internal heating. Qasim et al. [29] and Tawade et al. [30] discussed the flow of thin film using different fluids and geometries. Khan et al. [31] and Mahmood and Khan [32] investigated the effects of different variables on different fluids in their flow. According to our knowledge, there is no published work related to thermophoresis on heat transfer and thermal radiation characteristics of thin film micropolar liquid on the stretched plate under the transformations used in this research. Therefore, we have shown our interest in this paper to make an effort in discussing this new case. In this manuscript, exploration of the behavior of a steady, laminar, and two-dimensional flow of an incompressible micropolar fluid thin film into a porous medium past a stretched sheet was examined. Further, the inclusion of thermal radiation in the equation of energy is always used as a special case and, in most of the problems in the existing literature, the energy equation is used without radiation. In the papers cited above [17–20], the non-dimensional energy equation is written as (3*R* + 4)θ + 3*R Pr f* θ = 0, in which *R* is revealed as the radiation term. Clearly, if *R* becomes

zero, then the energy equation is reduced to θ" = 0, that is, the key parameter *Pr* and momentum boundary layer vanish and, therefore, the energy equation becomes meaningless. Therefore, we have tried to avoid this situation by using a transformation that is the same as in the works of [27,29,32] for the same problem as cited in the literature [17–20] with the addition of concentration. In recent research, most researchers used homotopy analysis method (HAM) to solve higher order nonlinear problems, and credit goes to Liao [33–35], who investigated such a wonderful technique to solve nonlinear higher order differential equations. Gul et al. [36,37] used the HAM method for the suitable range of parameters. Analytical solutions in series form are calculated using HAM. The effects of all parameters on velocity, microrotation, temperature, and concentration fields are shown graphically.
