2.1 Introduction

My experince show that many engineers/researchers in die casting are lacking the understanding of the basic fluid mechanics. This is my attempt to introduced this fundametal aspect of science to the die casting community. As someone who grow most his life around people who are experts in this area, I feel strongly that this knowldge cannot be avoided. The design of the process as well as the properties of cassting (sepcially magnsem alloys) are deterimed by the fluid mechanics/heat transer processes. I hope that others will join me to spread this knowldge.

There are numerous books about introdctery fluid mechanics I would suggest to redear who want to expained thier knowldge to read the book ``Fluid Mechanics'' by A.G. Hansen. 1967. I found this book to provide a clear illustretive picture of the physics. This chapter is a kind of summary of that book. I add only the most fundemantal asspects of the topic known as two phase flow.I hope that you will find this intersting and you will further continue read books which are dealing with fluid mechanics.

First we will interodce the nature of fluids and basic concepts from thermodynamics. Later we deals with the intergral analyses which will be divied into introduction of the control volume concept and Continuity equations. The energy equation will expained in the next section. Later will we will be descussing momentum equation. Lastly, the chapter will be dealing with the flow compressible gases. We refrain from dealing with to many topic such boundary layers, non-viscous flow, machinary flow etc because we believe that they are not essential to understand the rest of this book. Nevertheless, they are important and it is advaceble that the reader will read on these topics as well.