An experimental/numerical study of the turbulent boundary layer development along a surface with a sudden change in roughness
AUTOR(ES)
Avelino, Mila R
FONTE
Journal of the Brazilian Society of Mechanical Sciences
DATA DE PUBLICAÇÃO
2000
RESUMO
A theory for the description of turbulent boundary layer flows over surfaces with a sudden change in roughness is considered. The theory resorts to the concept of displacement in origin to specify a wall function boundary condition for a kappa-epsilon model. An approximate algebraic expression for the displacement in origin is obtained from the experimental data by using the chart method of Perry and Joubert(J.F.M., vol. 17, pp. 193-122, 1963). This expression is subsequently included in the near wall logarithmic velocity profile, which is then adopted as a boundary condition for a kappa-epsilon modelling of the external flow. The results are compared with the lower atmospheric observations made by Bradley(Q. J. Roy. Meteo. Soc., vol. 94, pp. 361-379, 1968) as well as with velocity profiles extracted from a set of wind tunnel experiments carried out by Avelino et al.( 7th ENCIT, 1998). The measurements are found to be in good agreement with the theoretical computations. The skin-friction coefficient was calculated according to the chart method of Perry and Joubert(J.F.M., vol. 17, pp. 193-122, 1963) and to a balance of the integral momentum equation. In particular, the growth of the internal boundary layer thickness obtained from the numerical simulation is compared with predictions of the experimental data calculated by two methods, the "knee" point method and the "merge" point method.
Documentos Relacionados
- Numerical prediction of bed-load and surface deformation on a granular bed sheared by a turbulent boundary-layer
- Effect of different surface roughnesses on a turbulent boundary layer
- A model of a turbulent boundary layer with a nonzero pressure gradient
- Numerical and experimental evaluation of the thermally stratified atmospheric boundary layer in wind tunnels
- Structure of the zero-pressure-gradient turbulent boundary layer