Journal of Aeronautical and Automotive Engineering (JAAE) p-ISSN: 2393-8579; e-ISSN: 2393-8587; Volume 3, Issue 2; April-June, 2016 pp. 43-48 © Krishi Sanskriti Publications http://www.krishisanskriti.org/Publication.html Vortex Control by a Vertical Splitter Plate Placed Upstream of a Square Cylinder in non-Newtonian Flow Nidhi 1 , Sudipto Sarkar 2 and Anamika Paul 3 1 Graduate Student, School of Chemical Engineering, Galgotias University, India 2 School of Mechanical Engineering, Galgotias University, India 3 School of Chemical Engineering, Galgotias University, India E-mail: 2 sudipto.sarkar@galgotiasuniversity.edu.in Abstract—In the present research work simulation of non- Newtonian fluid flow is carried out for vortex control of a square cylinder with a vertical upstream splitter plate. The unsteady two- dimensional Navier-Stokes equations (momentum and continuity equations) are solved using Ansys Fluent. Six different cases have been considered by varying the gap-ratio (G/a = 2.5 and 3, where ‘G’ is the gap between cylinder and plate and ‘a’ is the length of the side of the cylinder) and three different flow behavior indices (n = 0.8, 1 and 1.2). Changes in flow structures have been reported when the fluid flow is non-Newtonian and also the mean aerodynamic forces differ from Newtonian fluid flow. 1. INTRODUCTION The present paper deals with the understanding of rheology of fluid and analysis of fluid flow phenomena, using the CFD simulation software Ansys Fluent. Rheology of fluid is the classification of fluid group considering the Newton’s law of viscosity. The fluid obeying this law are called Newtonian and the rest of them are known as non-Newtonian fluids. They are further classified based on their dependency on time, temperature changes, etc. The maximum number of fluids available in nature and/or artificially made from industrial applications is non-Newtonian in nature. Considering the availability of non-Newtonian fluids in the environment (or artificially made), control of the vortices of bluff bodies by passive means was simulated in the present work. Bluff bodies are characterized usually by a huge unsteady downstream wake region that leads to considerable fluctuating fluid forces. The wake and the separated flow region can be reduced by the flow control which, in turn, reduces unsteadiness and the forces on the object. The flow control methods used to suppress the aerodynamic forces can be classified into two categories: 1. Active control methods in which the flow is controlled by supplying external energy by means of forced fluctuations and jet blowing [1]. 2. Passive control methods in which the flow is controlled by modifying the shape of the body or by attaching additive devices such as control rod, plate or roughness elements onto the body [2]. In the last few decades, research in the field of passive steady flow control has shown that a splitter plate set along the bluff body wake centerline reduces drag and may inhibit vortex shedding [3-6]. Malekzadeh and Sohankar [7] investigated the flow over cylinder and upstream control plate. The thickness of the plate varied from 0.1D to 0.9D and the gap between the cylinder and plate varied from 1.1D - 7D in between Re = 50 to 200. Three major regimes were observed in their work. In first and second regimes vortex shedding from control plate is suppressed, but in third regime, vortex formed behind the cylinder and plate. Also in the regime II, significant reduction of fluid forces is observed with a sudden increase in drag. Additionally, lift values is observed at critical distance for all control plate width. This drastic change is associated with the change in flow pattern from regime II to III and beginning of vortex shedding from control plate. They reported the reduction of time averaged drag coefficient of square cylinder with increase in Re and that the maximum reduction in aerodynamic forces was observed at Re = 200. Numerical simulation of unbounded creeping flow of dilute polymer solutions past cylinders and spheres using a suspension of dumbbells model with finite extensibility were performed by Chilcott and Rallison [8]. It was observed that the drag coefficient variation with the Weissenberg number for the flow past a sphere first decreases slightly, and then increases for all model parameters. Kato and Mizuno [9] measured the drag force in the Re range of 1×10 4 –5×10 4 for the flow past a cylinder with and without polymer. They found that drag forces in the Re range of 1–100 are barely affected by the polymers. Important drag reduction was found in the Re range of 10 3 –5×10 4 for the polymer