Abstract
Large-eddy and mixing length model simulations of convective flows over hills have been performed for a range of hill slopes and stabilities. For low hills, the fractional speed-up and normalized pressure drag are shown to decrease with increasing instability. For hills steep enough to cause separation in neutral conditions, the effect of convection is to reduce the size and strength of the separated bubble, although the normalized pressure drag is found to be almost independent of stability. Finally, the ability of effective roughness length parametrizations to represent the effects of the hills in convective conditions is assessed.
Similar content being viewed by others
References
Allen T. and Brown A.R. (2002). ‘Large-Eddy Simulation of Turbulent Separated Flow Over Rough Hills’. Boundary-Layer Meteorol 102:177–198
Athanassiadou M. and Castro I.P. (2001). ‘Neutral Flow Over a Series of Rough Hills: A Laboratory Experiment’. Boundary-Layer Meteorol 101:1–30
Belcher S.E., Newley T.M.J., and Hunt J.C.R. (1993). ‘The Drag on an Undulating Surface Induced by the Flow of a Turbulent Boundary Layer’. J. Fluid Mech.249:557–596
Belcher S.E. and Wood N. (1996). ‘Form and Wave Drag due to Stably Stratified Turbulent Flow Over Low Ridges’. Quart. J. Roy. Meteorol. Soc.16:159–186
Brown A.R., Derbyshire S.H., and Mason P.J. (1994). ‘Large-Eddy Simulation of Stable Atmospheric Boundary Layers with a Revised Stochastic Subgrid Model’. Quart. J. Roy. Meteorol. Soc.120:1485–1512
Brown A.R. and Grant A.L.M. (1997). ‘Non-Local Mixing of Momentum in the Convective Boundary Layer’. Boundary-Layer Meteorol 84:1–22
Brown A.R., Hobson J.M., and Wood N. (2001). ‘Large-Eddy Simulation of Neutral Flow Over Rough Sinusoidal Ridges’. Boundary-Layer Meteorol 98:411–441
Brown A.R. and Wood N. (2003). ‘Properties and Parametrization of the Stable Boundary Layer Over Moderate Topography’. J. Atmos. Sci. 60:2797–2808
Coppin P.A., Bradley E.F., and Finnigan J.J. (1994). ‘Measurements of Flow Over an Elongated Ridge and its Thermal Stability Dependence: the Mean Field’. Boundary-Layer Meteorol 69:173–199
Dörnbrack A. and Schumann U. (1993). ‘Numerical Simulation of Turbulent Convective Flow Over Wavy Terrain’. Boundary-Layer Meteorol 65:323–355
Frank H., Heldt K., Emeis S., and Fiedler F. (1993). ‘Flow Over an Embankment: Speed-up and Pressure Perturbation’. Boundary-Layer Meteorol 63:163–182
Grant A.L.M. and Mason P.J. (1990). ‘Observations of Boundary-Layer Structure Over Complex Terrain’. Quart. J. Roy. Meteorol. Soc.116:159–186
Hunt J.C.R., Leibovich S., and Richards K.J. (1988). ‘Turbulent Shear Flows Over Low Hills’. Quart. J. Roy. Meteorol. Soc.114:1435–1470
Milton S.F. and Wilson C.A. (1996). ‘The Impact of Parametrized Subgrid-Scale Orographic Forcing on Systematic Errors in a Global NWP Model’. Mon. Wea. Rev. 124:2023–2045
Taylor P.A., Sykes R.I., and Mason P.J. (1989). ‘On the Parametrization of the Drag Over Small-Scale Topography in Neutrally-Stratified Boundary-Layer Flow’. Boundary-Layer Meteorol 48:409–422
Wood N. and Mason P.J. (1993). ‘The Pressure Force Induced by Neutral, Turbulent Flow Over Hills’, Quart. J. Roy. Meteorol. Soc.119:1233–1267
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Allen, T., Brown, A.R. Modelling of Turbulent Form Drag in Convective Conditions. Boundary-Layer Meteorol 118, 421–429 (2006). https://doi.org/10.1007/s10546-005-9002-z
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10546-005-9002-z