===Alacsony sűrűségű áramlás===
▲Although the properties of low density flow are not necessarily applicable to hypersonic flight, most hypersonic vehicles are intended to cruise at high altitudes in low density fluids. Therefore, these flow conditions are often important in waverider design. In low density flows, air can no longer be considered to be a continuum because the distance between individual particles of air becomes so great that each particle begins to affect the aerodynamic properties of a body. Under these conditions, common aerodynamic relations, like the Euler and Navier-Stokes equations, break down. Instead, aerodynamic properties must be analyzed using kinetic theory. Some of the most important differences between low density flows and continuous flows include
Velocity slip: The viscous no-slip condition that says the velocity of air particles going past a body must be zero at the body surface, fails. Since friction is negligible in low density, the flow velocity at the body surface is no longer zero.
Temperature slip: The assumption that gas temperature at the body surface becomes equal to the temperature of the body surface material fails.
sebességtartományt: a [[lökéshullám]] viselkedése megváltozik; valódi gázok törvényei lépnek érvényre ([[disszociáció]], [[ionizáció]]); az aerodinamikai együttható függetlenné válik a [[Mach-szám]]tól.