**Numerical Analysis of Carbon Nanotube-Based Nanofluid Unsteady Flow Amid Two Rotating Disks with Hall Current Coatings and Homogeneous–Heterogeneous Reactions**

**Muhammad Ramzan 1,2,\*, Saima Riasat 1, Seifedine Kadry 3, Pin Kuntha 4, Yunyoung Nam 5,\* and Fares Howari <sup>6</sup>**


Received: 20 November 2019; Accepted: 4 January 2020; Published: 5 January 2020

**Abstract:** In the present exploration, our objective is to investigate the importance of Hall current coatings in the establishment of Cattaneo–Christov (CC) heat flux model in an unsteady aqueous-based nanofluid flow comprising single (SWCNTs) and multi-walled (MWCNTs) carbon nanotubes (CNTs) amid two parallel rotating stretchable disks. The novelty of the presented model is strengthened with the presence of homogeneous-heterogeneous (HH) reactions and thermal stratification effects. The numerical solution of the system of coupled differential equations with high nonlinearity is obtained by applying the bvp4c function of MATLAB software. To corroborate the authenticity of the present envisioned mathematical model, a comparison table is added to this study in limiting case. An excellent harmony between the two results is obtained. Effects of numerous parameters on involved distributions are displayed graphically and are argued logically in the light of physical laws. Numerical values of coefficient of drag force and Nusselt number are also tabulated for different parameters. It is observed that tangential velocity (function of rotation parameter) is increasing for both CNTs. Further, the incremental values of thermal stratification parameter cause the decrease in fluid temperature parameter.

**Keywords:** coatings; Hall current; Catttaneo-Christov heat flux; carbon nanotubes; homogeneous– heterogeneous reactions
