Python pip for package management

Unlike easy_install, pip features an uninstall command. :) I was able to install pip after python-setuptools as,

cd ~/downloads
git clone https://github.com/pypa/pip.git
cd pip/
sudo python setup.py install # root required.

This allowed a nice installation of ipython, removal of broken matplotlib, reinstallation of matplot lib including some compiling. I wonder if it plays nicely with numpy and scipy.... Ares showed,

sudo pip install scipy --upgrade

worked but that the BLAS libraries are not available. So close.... :| Also missing:

 f77blas,cblas,atlas.

Yet,

sudo pip install atlas

did work. tests failed though

system/fvSolution

From http://www.foamcfd.org/Nabla/guides/UserGuidese15.html

Equation solvers, tolerances and algorithms.

solvers {  // specify the linear solver.
   p       ICCG  1e-06 0;  // Incomplete-Cholesky preconditioned conjugate gradient for symmetric sparse matrices.   
   p       DCG   1e-06 0;  // Diagonally preconditioned conjugate gradient for symmetric sparse matrices.      
   p       AMG   1e-06 0 100;  // Algebraic multi-grid for symmetric sparse matrices.    

   U       BICCG 1e-05 0; // Incomplete-Cholesky preconditioned biconjugate gradient for asymmetric sparse matrices.   
   U       BDCG  1e-05 0; // Diagonally preconditioned biconjugate gradient for asymmetric sparse matrices.   
   U       BICCG 1e-05 0 2; // Gauss-Seidel for asymmetric sparse matrices.    


   U { solver smoothSolver; smoother GaussSeidel; tolerance 1e-06; relTol 0.01; nSweeps 1; maxIter 100; }
   k       BICCG 1e-05 0.1;

   epsilon BICCG 1e-05 0.1;
   epsilon{solver PBiCG; preconditioner DILU; tolerance 1E-9; relTol 0;}

   nuTilda BICCG 1e-05 0.1;

   R{solver PBiCG; preconditioner DILU; tolerance 1E-9; relTol 0;}

   }

Solution stops when tol or relTol are reached.  The tolerance is the difference between the lhs and rhs of the equation being solved.
 is often 0.

AMG:  Quick solution on coarse mesh; map results; second solution on fine mesh.




relaxationFactors { 
   p       0.3;
   U       0.7;
   k       0.7;
   epsilon 0.7;
   R       0.7;
   nuTilda 0.7;
   }

// ---------------------

PISO { // Pressure Implicit Split Operator
   nCorrectors 2;
   nNonOrthogonalCorrectors 0;
   }

OR

SIMPLE { // Semi-implicit method for pressure-linked equations.
   nNonOrthogonalCorrectors 0;  // I've have best residuals with 1 with structured 2D mesh; blow with 2; good with 3, 4, 5.
   }

SIMPLE makes one correction to an initial solution; PISO requires more but usually < 4.
This sets nCorrectors.  nNonOrthogonalCorrectors is used to compensate for a face not
being normal to the cell centre.
// ---------------------------

OpenFoam: ill defined primitiveEntry starting at keyword

Usually indicates the lack of a space between the keyword and the following parenthesis.

vnc

Server: $ sudo apt-get install tightvncserver $ vi ~/.vnc/xstartup and replace /etc/X11/Xsession & with fluxbox & then, $ tightvncserver Displays new display number. Client: $ sudo apt-get install xtightvncserverviewer $ xtightvncviewer ipaddress:1 where `1' is the display number.

Decimating (and more) CFD results with Python

This two liner removes all time directories for times smaller than 0.1ms. It's native Python. import os, shutil d = '/home/me/CFD/tilt3D_9/p50'; a = os.listdir(d); b = [i for i in a if len(i) in [7,8] and i[0] in ['0','1','2','3','4','5','6','7','8','9']]; [shutil.rmtree(d + '/' + i) for i in b]

Enabling boot logging on ubuntu

Edit /etc/default/bootlogd Change BOOTLOGD_ENABLE=No to BOOTLOGD_ENABLE=yes

listing the unique login user name attempts

:$ zgrep ssh /var/log/auth*|grep "Invalid user"|cut -d ' ' -f 8|sort|uniq -c|sort -n|tail -n 17

I've got,

       1 router
       1 sido
       1 test
       1 ubuntu
       3 oracle
 2381 user

Great script, that....