View source for Sig WindE/Validation Cases RUSHIL

This is a documentation of my trial to simulate the RUSHIL experiment (main page is: [[Sig_WindE_-_Validation_Cases]]) - 

I have tried simulating the experiment by Khurshudyan et al.[http://cfd.mace.manchester.ac.uk/cgi-bin/cfddb/prpage.cgi?69&EXP&&database/cases/case69&cas69_head.html&cas69_desc.html&cas69_meth.html&cas69_data.html&cas69_refs.html&cas69_rsol.html&1&1&1&0&1&unknown], which is a wind tunnel experiment with a 2D hill of several aspect ratios, named also RUSHIL experiment. The latest comparison to it was published by Kasmi and Mason 2010 [http://onlinelibrary.wiley.com/doi/10.1002/we.390/full]. Because the top boundary condition is not regular, I had considerable differences with the experiment and have given up for the meanwhile (since it is not similar to real ABL - which is more in my interest - and so not in my focus). Below is what I did for creating a STL surface for the case, just for reference.

'''Creating the STL surface'''

The shape of the 2D hill is an analytical function described in [http://onlinelibrary.wiley.com/doi/10.1002/we.390/full] as:

<math>x = \frac{1}{2} \xi \left[ 1+\frac{a^2}{\xi^2+m^2(a^2- \xi^2)} \right]   </math> for <math> |x| \leq a</math>

<math>z = \frac{1}{2} m \sqrt{a^2-\xi^2} \cdot \left[ 1- \frac{a^2}{\xi^2+m^2(a^2- \xi^2)} \right] </math>

where <math> m = \frac{h}{a}+\sqrt{\frac{h}{a}+1}</math> and h is the height of the hill (<math>h = 0.117 [m]</math>) and a is the length of the hill. <math>\xi</math> is a parameter that changes from 0 to a. The aspect ratio of the hill is 3, 5 and 8.

The experimental setting was:

logarithmic inlet profile with <math>z_0=0.157 \cdot 10^-3 [m]</math>, <math>u_{*} = 0.178 \left[ \frac{m}{s}\right]</math> which gives for instance <math>U_\infty = 3.9 \left[ \frac{m}{s} \right]  </math > at <math> z = 1 [m] </math>

'''1''' The Profile was created with the desired discretization in a spreadsheet program. Column x (1st column) was the width of the hill (arbitrary width), 2nd column is x and the third z. Finally the 3 columns where exported as a csv file [[Media:RUSHIL_8.csv.tar.gz|RUSHIL_8.csv]] (This should be according to the .xyz format).

Next, paraview is used to transform the csv into a STL surface, as explained  [http://www.cfd-online.com/Forums/openfoam/79032-movedynamicmesh.html in this thread], an reiterated here:

'''2''' The profile is uploaded in paraview.

'''3''' Open the csv in paraview using the csv reader, choose 1 column for each coordinate.

'''4''' Use the "TableToPoints' filter to obtain an array of points. The columns choice here is important so that the result will be a right hand side coordinate system. For the file above the order is '''y''' - '''x''' - '''z'''

'''5''' Use the delaunay tool to "map" a suface from the point (The Delaunay 2D filter)

'''6''' Save the data, you 'll be able to save it as an stl