∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
∇
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
Fig. 12.4:
The pressure ratio as a function of the dimensionless time

CHAPTER 13
Oblique Shock
13.1
Preface to Oblique Shock
= 0
Fig. 13.1:
A view of a straight normal shock as
a limited case for oblique shock
In Chapter (
5
), discussion on a normal
shock was presented. A normal shock
is a special type of shock wave.
The
other type of shock wave is the oblique
shock.
In the literature oblique shock,
normal shock, and Prandtl–Meyer func-
tion are presented as three separate
and different issues. However, one can
view all these cases as three different
regions of a flow over a plate with a de-
flection section. Clearly, variation of the
deflection angle from a zero (
δ
= 0
) to a
positive value results in oblique shock. Further changing the deflection angle to a
negative value results in expansion waves. The common representation is done
by not showing the boundaries of these models. However, this section attempts to
show the boundaries and the limits or connections of these models
1
.
1
In this chapter, even the whole book, a very limited discussion about reflection shocks and collisions
of weak shock, Von Neumann paradox, triple shock intersection, etc are presented. The author believes
that these issues are not relevant to most engineering students and practices.
Furthermore, these
issues should not be introduced in introductory textbook of compressible flow. Those who would like
to obtain more information, should refer to J.B. Keller, “Rays, waves and asymptotics,” Bull. Am. Math.
Soc. 84, 727 (1978), and E.G. Tabak and R.R. Rosales, “Focusing of weak shock waves and the Von
Neuman paradox of oblique shock reflection,” Phys. Fluids 6, 1874 (1994).
241