2 nd International Conference on Advances in Mechanical Engineering and its Interdisciplinary Areas (ICAMEI-2015) Design and Analysis of Low Speed Water Tunnel for Flow Visualization of Bluff Body Harshad Kalyankar, Rishabh Melwanki, Dinesh Choudhary, Siddharth Jethwa and Dipak Chaudhari Department of Mechanical Engineering, Vidyavardhini’s College of Engg. & Tech., University of Mumbai Abstract Water tunnel is an indispensible experimental facility used for testing the hydrodynamic behavior of submerged bodies in flowing water. It has its application in visualizing the flow behavior over different structures, studying the boundary layer phenomenon i.e. flow separation, vortex shedding etc. The design philosophy to be employed for designing a low speed water tunnelis discussed in this paper. Different components, their significance and the key decisions that need to be taken while designing them are explained. A water tunnel with test section dimensions WHL: 0.10 × 0.15 × 0.70 m capable of generating flow speed in the range of 0–0.21 m/s is designed, analyzed & fabricated for flow visualization purpose using External Dye Injection technique. A Kirloskar Brothers Ltd. KDS-225++,with flowrate 19.08m 3 /hr, and maximum pressure head of 26m is used as the pump. Suitable fabrication of dye injection technique for visualization purpose is also additionally discussed. The design is computationally analyzed in Autodesk Simulation CFD 2013 package, for determining the flow characteristics throughout setup and thus optimizing the setup to have a laminar flow throughout with satisfactory flow velocities (velocity achieved was 0.08m/s for a particular set of input parameters which is desirable). INTRODUCTION The requirement for the water tunnel is to visualize a wide range of flows. The flow ranges differ according to the fluid, flow speed, problem size, and solid boundaries, special flow features such asflow with heat addition or flow of electrically charged fluids. For a water tunnel, the fluid is restricted to water. Any water tunnel or wind tunnel system imposes restrictions on the flow speed and problem size due to tunnel power capabilities, structural design and size. As for the flow speed and problem size, they do not comprise a difficult problem since the similarity parameters and problem scaling provide a solution. Thus, by the proper combination of similarity parameters and problem sizing, a wide range of problems may be modeled in the tunnel. Water tunnel is of paramount importance for flow visualization. Flow visualization is the process of making different phenomena of the fluid flow visible. As for the research purposes, flow visualization plays a key role in understanding the flow behavior in order to assist the researcher in formulating more consistent theories regarding the particular flow. Since, the fluid mechanical problem exhibits a high degree of complexity, the brute force approach of solving the problem is inefficient, specialized theories for different flows must be formulated in order to simplify the flow problem and focus on the problem in hand. WATER TUNNEL SURVEY In order to have a better idea about the common sizes and capabilities of water tunnels, a survey was made. The survey data are mainly concerned with the test section flow speed and tunnel size, represented by the test section dimensions and tunnel contraction ratio.