Two-phase nanofluid over rotating disk with exponential variable thickness

Purpose: The purpose of this paper is to investigate the effect of nanofluid over rotating disk with the exponential variable thickness (Formula presented.) (c > 0, b > 0) and to analyze Brownian motion and thermophoresis of Buongiorno model on the disk embedded in nanofluid-saturated porous media.

Design/methodology/approach: Using the generalized von Karman transformation, the boundary layer governing equations are transformed into semi-similar forms solved by bvp4c in MATLAB.

Findings: The effects of the thickness parameter a, the shape parameter b, the Brownian motion parameter Nb and thermophoresis parameter Nt on flow, heat and mass transfer are analyzed. With the increase of thickness parameter a, the radial velocity first decreases and then increases, showing the opposite trend on the two sides of the peak value. Moreover, temperature and concentration rise as the Brownian motion parameter Nb becomes larger.

Originality/value: To the best of the authors’ knowledge, this is the first work that has been done on rotating disk with exponential variable thickness in nanofluid. The impact of the two slip effects, namely, Brownian motion and thermophoresis, on the nanofluid boundary layer flow, heat and mass transfer because of rotating disk with exponential variable thickness (Formula presented.) (c > 0, b > 0) has been addressed in this study.