Yield stress measurement techniques: A review

This contribution is to add to the timely celebration of Professor R. B. Bird's outstanding career and accomplishments. Following introductory remarks on material/fluid types, the paper reviews the concept of yield stress. Although yield stress has been studied for several decades, it is still very much a topic of current interest. This paper covers phenomenological yield stress models as well as experimental techniques to measure yield stress. It also discusses, in particular, problems associated with very low yield stress measurements that occur with bio-fluids such as blood.