Numerical study of entropy production minimization in Bodewadt flow with carbon nanotubes

This work aims to analyze three-dimensional Bodewadt nanofluid flow. An infinite disk in Bodewadt flow is stationary while fluid very far away from the disk rotates with uniform angular velocity. Water and kerosene oil are treated as base liquids. Both single-wall (SWCNTs) and multiple-wall (MWCNTs) carbon nanotubes are employed. Viscous dissipation effect is addressed. Entropy generation is analyzed by implementing second law of thermodynamics. The governing non-linear PDEs are converted into non-dimensional ODEs using transformation process. Shooting technique subject to Runge-Kutta fifth order algorithm (bvp4c) is implemented for the solution process. Velocities (radial, tangential and axial), temperature, entropy production rate, Bejan number, skin friction and Nusselt number are addressed for impact of involved variables. Velocity components (axial, radial and tangential) intensify with higher nanoparticle volume fraction while it reduces for higher ratio of radial stretching rate to rotation rate parameter. Enlargement in temperature of fluid is observed against higher estimations of nanoparticle volume fraction, Eckert number and ratio of radial stretching rate to rotation rate parameter. Entropy production rate is minimized via higher nanoparticle volume fraction. Bejan number is an increasing function of Eckert number, ratio of radial stretching rate to rotation rate parameter and nanoparticle volume fraction. Higher values of ratio of radial stretching rate to rotation rate parameter and nanoparticle volume fraction lead to an increment in Nusselt number. Moreover impact of multiple-wall CNT is efficient when compared with single-wall CNT. (C) 2020 Elsevier B.V. All rights reserved.