Mathematics of cyclic redundancy checks

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The Cebeci–Smith model is a 0-equation eddy viscosity model used in computational fluid dynamics analysis of turbulent boundary layer flows. The model gives eddy viscosity, μt, as a function of the local boundary layer velocity profile. The model is suitable for high-speed flows with thin attached boundary-layers, typically present in aerospace applications. Like the Baldwin-Lomax model, this model is not suitable for cases with large separated regions and significant curvature/rotation effects. Unlike the Baldwin-Lomax model, this model requires the determination of a boundary layer edge.

The model was developed by Tuncer Cebeci and Apollo M. O. Smith, in 1967.

Equations

In a two-layer model, the boundary layer is considered to comprise two layers: inner (close to the surface) and outer. The eddy viscosity is calculated separately for each layer and combined using:

μt={μtinnerif yycrossoverμtouterif y>ycrossover

where ycrossover is the smallest distance from the surface where μtinner is equal to μtouter.

The inner-region eddy viscosity is given by:

μtinner=ρ2[(Uy)2+(Vx)2]1/2

where

=κy(1ey+/A+)

with the von Karman constant κ usually being taken as 0.4, and with

A+=26[1+ydP/dxρuτ2]1/2

The eddy viscosity in the outer region is given by:

μtouter=αρUeδv*FK

where α=0.0168, δv* is the displacement thickness, given by

δv*=0δ(1UUe)dy

and FK is the Klebanoff intermittency function given by

FK=[1+5.5(yδ)6]1

References

  • Smith, A.M.O. and Cebeci, T., 1967. Numerical solution of the turbulent boundary layer equations. Douglas aircraft division report DAC 33735
  • Cebeci, T. and Smith, A.M.O., 1974. Analysis of turbulent boundary layers. Academic Press, ISBN 0-12-164650-5
  • Wilcox, D.C., 1998. Turbulence Modeling for CFD. ISBN 1-928729-10-X, 2nd Ed., DCW Industries, Inc.

External links