Stefan LLEWELLYN SMITH
EBUII 574
x23475
http://mae.ucsd.edu/~sgls
Homework VI
Due
Friday February 28, 2019, in class (or before).
Problems (MYO is the textbook; 8th edition)
MYO 11.3
MYO 11.7
MYO 11.11
MYO 11.13
MYO 11.18
MYO 11.24
MYO 11.26
Write a paragraph about the Austrian physicist Mach and his
research in fluid mechanics.
Comments
The next major section of the book which covers compressible flow.
This homework covers the first few sections, which are mostly review
material from thermodynamics.
Section 11.1 reviews the idea gas law. This should be familiar, but
is a good time to review enthalpy, the ratio of specific heats and
entropy.
Section 11.2 discusses the speed of sound. Sound is the basic linear
response of a compressible fluid: fluid particles expand and
contract, leading to a propagating signal. Since this is the
result of the interplay of density and pressure, the speed of
sound comes out as the square root of the derivative of pressure
with respect to density. Hence incompressible fluid corresponds to
infinite sound speed: the fluid adjusts instantaneously everywhere.
This is not possible in reality, but is a good approximation if the
speed of sound is much larger than the characteristic velocity of
fluid in the system, i.e. if the Mach number, V/c, is small.
Section 11.3 explores different flow regimes at different Mach
numbers. One can distinguish incompressible flow, compressible
subsonic flow, transonic flow, (compressible) supersonic flow, and
hypersonic flow. In supersonic flow, the disturbance induced by a
body is localized inside a Mach cone
The rest of the chapter discusses flow in ducts and shocks,
combining the above material with fluid flow. It can be challenging,
so mastering Sections 11.1–3 is a good start.