## 1 Introduction  
The development and evolution interest of innovative study in the area of technology science led to increasing the production of improved and modified machine tools such as synthetic lubricants and pored bearings, etc. The performance of pored bearings can be compared with the standard bearings because they have a feature like self-lubricating, which enhances their life span. The micropolar fluid is one type of fluids, which include couple stresses and the local rotating inertia. The theory of micropolar fluid is a subject of interest of several tribologists. The theory of micropolar fluid was revealed to the world by [PERSON] [1]. He described that the micropolar fluid has some unique advantages, such as the modeling of a wide variety of fluid flow through several media. [PERSON] et al. [2] reported the analytical solution for heat and mass transfer of micropolar fluid flow over a moving vertical plate in a porous medium. [PERSON] [3] derived the modified Reynolds equation for the porous media applying the Brinkman-extended Darcy equation. [PERSON] et al. [4] explained the heat and fluid flow characteristics of micropolar fluid flowing through a porous moving surface. They applied a uniform heat flux condition to drive the general expressions of different parameters. [PERSON] et al. [5] and [PERSON] et al. [6]analyzed the performance of one-dimensional porous slider bearing by developing the generalized Reynolds equation in case of micropolar fluid. [PERSON] et al. [7] investigated the flow of micropolar fluid over a stretchable surface, and they found that the micropolar fluid-induced drag decline and enhances the wall couple's stress and the heat transfer rate of the stretched surface. Under squeeze film lubrication, [PERSON] et al. [8] clarified the skin-friction coefficient and heat transfer rate boosts and wall couple stress declines if the micropolar fluid vortex viscosity parameter grows in case of micropolar fluid flow on a vertical plate. [PERSON] et al. [9] explained that the micropolar fluid possesses enhanced viscosity especially in thin-film lubrication, which is a singular characteristic of micropolar lubricant. [PERSON] et al. [10] investigated the micropolar fluid flow through a horizontal circular cylinder. On the other hand, the capability of heat transportation is required to meet the recent request of energy, and this can be achieved by employing liquid with its more impressive thermophysical features. The pioneering act on nanofluid was carried out by [PERSON] [11]. Such type of fluids is the combination of nanoparticles in a mixture of base liquid. An augmentation in heat exchange using nanomaterials is affected by various mechanisms like sedimentation, Brownian motion, insertion of particles, transport of ballistic conduction, and thermophoresis. Nanomaterials possess fundamental features due to which it is essential in several applications regarding heat mechanisms like fuel chamber, cooling engine automobile, hybrid-electric engines, pharmacological method, boiler gas outlet, local refrigerator, temperature control, and crushing processes. [PERSON] et al. [12] carried out the aspect of nanofluid mixed convective flow past a radiate cone in a porous medium. The investigations of nanofluids flow by combined convective past cylinder and sphere saturating porous medium were studied by [PERSON] et al. [13], [PERSON] and [PERSON] [14], [PERSON] et al. [15] and [PERSON] et al. [16]. [PERSON] et al. [17] examined the magneto-nanofluids flow past a porous stretching cylinder with multiple slips and radiation effects. [PERSON] et al. [18] analyzed the nanofluid forced convective flow across a circular cylinder. However, various attempts have been established about the use of nanofluids to enhance heat transfer [19; 20; 21; 22; 23]. Propelled by the previously mentioned investigations, the intention here is to analyze the mixed convective flow of a micropolar nanofluid past a horizontal circular cylinder in a saturating porous medium employing convective boundary conditions.