Modeling laminar sheet flow over rough surfaces

Gliding Swifts Attain Laminar Flow over Rough Wings

Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1-2% of chord length on the upper surface--10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the win...

Modeling Rough Surfaces

The effective slip length and vortex formation in laminar flow over a rough surface

The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary pla...

Pressure Drop of Fully-developed, Laminar Flow in Rough Microtubes

The characteristics of fully-developed, laminar, pressure-driven, incompressible flow in rough circular microchannels are studied. A novel analytical model is developed that predicts the increase in pressure drop due to wall roughness in microtubes. The wall roughness is assumed to posses a Gaussian isotropic distribution. The present model is compared with experimental data, collected by other...

Stability of Shear Layers over Rough Surfaces

Presence of surface imperfections may have significant impact on the stability of the adjacent shear layer and on the laminar-turbulent transition process in this layer. The main objective of the present study is the quantitative assessment of such effects in the case of distributed surface roughness. The analysis is focused on the linear stability theory and considers asymptotic as well as tra...