Heatlines and other visualization techniques for confined heat transfer systems

Efficient visualization techniques are required to understand the flow physics for any numerical simulation. For convective heat transfer problems, most widely used techniques to visualize the fluid flow and heat transfer are streamlines and isotherms respectively. These methods are not sufficient to address the degrees of complexity associated with the complicated convective problems. Thus, different visualization techniques have been developed to represent the results depending on the problem. In this article, an effort has been made to collate visualization techniques in literature for convective heat transfer system like, heatlines, energy streamlines, energy flux vectors, proper orthogonal decomposition (POD), Poincare map etc. The fundamentals of different techniques are briefly discussed, applications of these techniques are shown with proper examples. The usefulness and limitations of these techniques are also discussed. Heatline is found to be the best visualization tool for two dimensional steady situations. However, in 3D and transient scenario Lagrangian approach or POD can be used.