Universal Journal of Mechanical Engineering 7(5): 264-271, 2019 http://www.hrpub.org DOI: 10.13189/ujme.2019.070503 Oscillating Free Convection Flow between Two Parallel Plates with Mass Diffusion Fasihah Zulkiflee 1 , Ahmad Qushairi Mohamad 1 , Mohd Rijal Ilias 2 , Sharidan Shafie 1,* 1 Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, Malaysia 2 Department of Mathematical Sciences, Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, Malaysia Received July 1, 2019; Revised August 22, 2019; Accepted September 22, 2019 Copyright©2019 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract This paper studied unsteady free convection flow between two parallel plates with mass diffusion. One of the plates is considered oscillating. Appropriate non-dimensional variables are used to reduce the dimensional governing equations along with imposed initial and boundary conditions. The exact solution to velocity, temperature and concentration profiles are obtained using the Laplace Transform technique. The graphical results of the solutions are presented to illustrate the behavior of the fluid flow with the influence of Schmidt number, Prandtl number, oscillating parameter, Grashof and mass Grashof number. The corresponding expressions for skin friction, Nusselt number and Sherwood number are also calculated. It is observed that increasing Prandtl and Schmidt numbers will increased the Nusselt number but decreased the skin friction. Keywords Free Convection, Mass Diffusion, Oscillating, Parallel Plates 1. Introduction The fluid flows between parallel plates have received much attention due to the various applications involving heat transfer. It has various applications such as in petroleum industry, purification of crude oil, pumps accelerators and power generators [1]. Researchers have taken a great interest investigated problem regarding free convection flow between two parallel plates [2-4]. Singh investigated transient natural convection between two vertical walls heated/cooled asymmetrically [5]. Narahari [6] investigated natural convection flow in vertical channel with ramped wall temperature at one boundary while Paul [2] investigated transient free convective flow in vertical channel with constant temperature and constant heat flux. In other research, Jha [7] investigate free convection heat and mass transfer flow in a vertical channel with Dufour effect and then extended their research with diffusion-thermo effects on free convective heat and mass transfer flow in a vertical channel with symmetry boundary condition [8]. Oscillatory flow between parallel plates has received some attention of the researchers as because researchers found that oscillatory plates can higher the rates of heat transfer [9]. There are many researchers considering oscillation in their research such as [10-12] but not many considering oscillations in between two parallel plates. The literature survey shows that researches on oscillating flow between two parallel plates are very few. Reddy [13] investigated unsteady MHD free convection oscillatory Coette flow through a porous medium with periodic wall temperature in presence of chemical reaction and thermal radiation. While MHD oscillatory flow through a porous channel saturated with porous medium was investigated by Falade [14]. Bunyonyo [9] investigated unsteady oscillatory Coette flow between vertical plates with constant radiative heat flux. Their research shows that the oscillatory parameter played a greater role in causing the fluid to oscillate inside the Coette channel. Motivated by above investigations, the present analysis is to investigate oscillatory free convection flow between two parallel plates with mass diffusion. This problem will be solved using Laplace Transform method to obtain exact solution. 2. Materials and Methods Consider an unsteady free convection flow between two parallel plates with mass diffusion. Oscillating plate at y’=0 is considered. The configuration flow of the problem is presented in Figure 1. The flow is governed by the following equations under the usual Boussinesq’s approximations: