Sig WindE/Validation Cases

Page under construction The aim of this page is to hold validation cases for ABL (Atmospheric Boundary Layer) flows that are of interest to anybody starting to model in OF. The page will hold links to databases and articles describing experiments, and also instructions on how to make meshes and set boundary conditions that give fair results, hopefully the end result will be complete cases. The simulations I perform, and refer to mainly in this text are RANS with k-epsilon turbulence closure models, using simpleFoam. Most of the simulations were done according to the excellent Martinez 2011 Ms.C. thesis [1]

(0) Maintaining a logarithmic inlet profile over a 2D domain

The wall function boundary condition implemented in OF is the Nikuradse's grain of sand roughness. It produces an anomaly in the k profile in the first cell above the ground which propagates upwards and down-flow. This is discussed extensively in the literature, and alternative wall functions have been suggested such as Richards and Hoexy 1993 (RH). There has lately been a very good documentation of testing this anomaly by Martinez in his Ms.C. thesis [2].

File:BL2D.tar checked on OF 2.1

Attached case ("BL2Dtemplate") has python scripts using the pyFoam library to run different z0 values. run with ./Allrun .

(1) Flow over Isolated 2D Hill (checked on OF 2.1)

The 2D simple hill from Martinez 2011 whose shape is given by

$y\left(x\right) = -\frac{H}{6.04844}\left[J_0(\Lambda)I_0(\Lambda\frac{x}{a})-I_0(\Lambda)J_0(\Lambda\frac{x}{a})\right] \; \mathrm{for} \; |x-x_0| \leq a$

$y\left(x\right) = 0 \; \mathrm{for} \; |x-x_0| > a$

The mesh is created with blockMesh, and a template file, and also a python script that writes the hill shape as a polyline object in the blockMeshDict. The mesh grading was done by breaking the control box into 3 segments - upwind, hill area and downwind (unlike the Martinez mesh grading tanh scheme). The case with the python script, ready to run (./Allrun) is attached here

File:2DBump.tar (checked on OF 2.1)

It compares the results with figures 21a,21b and 21c from Martinez 2011.

Another 2D case I tried simulating though unsuccessfully is mentioned here.