A heat sink is a kind of heat exchanger used as a cooling system for electronic components due to simplicity, low cost, and a reliable manufacturing process. The heat sink can be divided by plate and pin fin shapes. In the past decade, several published articles have focused on studying the effects of fin shapes and arrays of heat sinks on flow characteristics and thermal performance with forced convection. However, only a few publications have focused on the flow directions (parallel and impingement flows) and flow behaviors (bypass and non-bypass flows) through the heat sink, which are necessary for fin and overall cooling system design. The purpose of this article is to summarize the publications with respect to experimental research on the fluid flow directions and behaviors through heat sinks as well as offering guidelines for future research. (C) 2014 Elsevier Ltd. All rights reserved.