The purpose of the course is to provide state-of-the-art 
information on physical modelling, experimental and 
numerical simulation of thermohydraulic instability 
phenomena. After a review of basic consideration and 
fundamentals concerning the conditions leading to 
formation of different internal and free surface flow 
instabilities, the emphasis will be given to the 
experimental visualisation and measurement techniques 
developed to observe and quantify these phenomena. Then 
the numerical tools available to predict the occurrence 
and the behaviour of flow instabilities will be discussed 
and exemplified. Finally, some typical industrial 
applications where flow instability happens as a limit of 
the process will be presented.