Fluid Dynamics (MCEN90008)

AIMS

This subject builds upon previous fluids subjects, providing students with the basic skills necessary to calculate fluid flows around bodies. Broadly speaking the subject is divided into two units; Unit 1: potential flow and Unit 2: compressible flow. These could equally be described as subsonic and supersonic aerodynamics respectively. Fluid flows have broad reaching applications in many engineering systems and examples as broad as building ventilation, mixing, as well as meteorological applications are considered in unit 1. The supersonic course is more firmly concentrated on aeronautical / astronautical applications.

Both units will start from the basic equations of motion governing fluid flow, and build a useable set of tools that enable the students to calculate flow fields in potential and supersonic flows. This approach will give students a clear sense of the origins of the tools that they use, and also a clear sense of the limitations. Such knowledge is necessary since these theories provided much of the backbone to early computational fluid dynamics packages used in industry.

The two units are strongly linked by the same goal. Throughout the potential flow unit, we build slowly from first principles, proving the utility of potential flow solutions, adding building block flows until eventually the course culminates with a demonstration of how these techniques can be used to calculate the flow (and lift coefficient) of subsonic airfoils. The supersonic unit follows a similar approach, building from first principles, until we eventually develop a set of tools that enables the calculation of the flow (and lift coefficient) of supersonic airfoils. In doing so, students will be introduced to many aspects of supersonic aircraft design.

INDICATIVE CONTENT

This subject introduces students to analysis techniques used in subsonic and supersonic flows. Topics covered include (Unit 1) basic introduction to inviscid flow with and without vorticity; concepts and analysis using stream function and velocity potential; incompressible viscous flow past bodies with vortex shedding; magnus effect; complex velocity potential; (Unit 2) speed of sound; aerodynamic heating; normal and oblique shock waves; expansion fans; theories of thin airfoils; shock expansion theory; boundary layer and shock wave interactions; the `sound barrier’; experimental techniques.