Flow across a forest edge (2013)

First sequence (2013)

Model Setup Total domain size (x|y|z): 2304m x 1152m x 384m Grid spacing (x|y|z): 3m x 3m x 3m Number of grid points (x|y|z): 768 x 384 x 128 Forest size: 1000m x 1152m x 30m Simulated time: 3h CPU-time: 18h 20m Number of CPUs: 512 Machine/ processor type: SGI Altix ICE at ​HLRN / Intel Xeon Gainestown Visualization software: ​VAPOR

Project: High-resolution LES studies of the turbulent exchange processes between forest and atmosphere in a forest-edge flow regime Responsible: Farah Kanani?, Björn Maronga? Description: The first sequence shows the development of coherent turbulence structures above a forest canopy downstream of a forest edge. A neutral wind-tunnel-like flow is simulated with the mean flow direction from left to right, perpendicular to the forest edge. The animation spans over 180 seconds of simulated time and runs at an accelerated pace. Only a part of the model domain is shown. The forested part of the domain is surrounded by the light green iso surface. The turbulence structures are visualized by the absolute value of the three-dimensional rotation, with highest values in pink and lowest values in yellow. The effect of form and viscous drag of the forest on the turbulent flow is modeled by PALMs canopy model. Upstream of the forest, the 10-m wind is approximately 6m/s. The approaching flow is turbulent with different scales of turbulence being randomly distributed. Entering the forest volume, the flow is decelerated and turbulence is efficiently damped by the forest drag. Above the forest, turbulence is effectively generated due to the strong velocity shear near the forest top. With increasing distance from the forest edge, the developing turbulence structures grow in size and strength, forming a layer of high turbulence activity, within the flow adjusts to the new surface conditions. This layer represents an internal boundary layer. Download Video Format File size Flash (.flv) 7.5mb Download (3D) MPEG (.avi) 7.8mb Download (3D)