Effect of a flat plate on heat transfer and flow past a three side-by-side square cylinders using double MRT-lattice Boltzmann method

In this work, a numerical study was carried out to simulate laminar flow and heat transfer characteristics in a 2D dimensional horizontal channel, including three heated square cylinders placed side-by-side and equally spaced. A controlled flat plate is inserted behind obstacles. The Double Multiple Relaxation Time Lattice Boltzmann Method (MRT-LBM) is adopted as the numerical method were using the MRT-D2Q9 model and the MRT-D2Q5 model to treat the flow and the temperature fields respectively. The problem regarded, in this paper, is a laminar and incompressible flow. The air (Pr = 0.71) is the fluid circulating in the channel, its physical properties, except the density, are supposed to be constant. The top and bottom channel walls are assumed to be adiabatic, the airflow incoming with cold temperature which is fixed to θc = - 0.5, each cylinder at a constant hot temperature equal to θh= 0,5. The flow is fully developed with a parabolic velocity profile at the inlet and at the outlet of the channel. also, in the outlet, the temperature and velocity gradients are assumed to be zero. The effects of plate position and length on the fluid flow and the heat transfer are examined in terms of streamlines and isotherms contours visualizations.

I. Introduction

Due to its intrinsic complexities and importance of the fluid flow and heat transfer and more specifically, the suppression of the vortices shedding around a bluff body has been the subject of several studies in many practical engineering applications, such as flows past an air-plane, a submarine and an automobile, heat exchanger systems, electronic cooling, gas turbine blades, etc. Thus, a host of experimental and numerical investigations has been carried out, during last years, to understand the flow and heat transfer past of square cylinders, circular or any other geometric shapes of a cylinder in cross flows with or without control plate. Nevertheless, few works have addressed the interference effects between multiple cylinders and the number of publications available becomes drastically smaller as the number of cylinders involved increases [1]–[5]. As well, there is very little investigation into the coupling between fluid flow and heat transfer.