Riabouchinsky solid
Encyclopedia
In fluid mechanics
a Riabouchinsky solid is a technique used for approximating boundary layer separation
from a bluff body using potential flow
. It is named after Dimitri Pavlovitch Riabouchinsky
.
Riabouchinsky solids are typically used for analysing the behaviour of bodies moving through otherwise quiescent fluid (examples would include moving cars, or buildings in a windfield).
Typically the streamline that touches the edge of the body is modelled as having no transverse pressure gradient and thus may be styled as a free surface
after separation.
The use of Riabouchinsky solids renders d'Alembert's paradox
void; the technique typically gives reasonable estimates for the drag offered by bluff bodies moving through inviscid fluids.
Fluid mechanics
Fluid mechanics is the study of fluids and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion...
a Riabouchinsky solid is a technique used for approximating boundary layer separation
Flow separation
All solid objects travelling through a fluid acquire a boundary layer of fluid around them where viscous forces occur in the layer of fluid close to the solid surface. Boundary layers can be either laminar or turbulent...
from a bluff body using potential flow
Potential flow
In fluid dynamics, potential flow describes the velocity field as the gradient of a scalar function: the velocity potential. As a result, a potential flow is characterized by an irrotational velocity field, which is a valid approximation for several applications...
. It is named after Dimitri Pavlovitch Riabouchinsky
Dimitri Pavlovitch Riabouchinsky
Dimitri Pavlovitch Riabouchinsky was a Russian French fluid dynamicist noted for his discovery of the Riabouchinsky solid technique. He also independently discovered equivalent results to the Buckingham Pi Theorem in 1911....
.
Riabouchinsky solids are typically used for analysing the behaviour of bodies moving through otherwise quiescent fluid (examples would include moving cars, or buildings in a windfield).
Typically the streamline that touches the edge of the body is modelled as having no transverse pressure gradient and thus may be styled as a free surface
Free surface
In physics, a free surface is the surface of a fluid that is subject to constant perpendicular normal stress and zero parallel shear stress,such as the boundary between two homogenous fluids,for example liquid water and the air in the Earth's atmosphere...
after separation.
The use of Riabouchinsky solids renders d'Alembert's paradox
D'Alembert's paradox
In fluid dynamics, d'Alembert's paradox is a contradiction reached in 1752 by French mathematician Jean le Rond d'Alembert. D'Alembert proved that – for incompressible and inviscid potential flow – the drag force is zero on a body moving with constant velocity relative to the fluid...
void; the technique typically gives reasonable estimates for the drag offered by bluff bodies moving through inviscid fluids.