Granular Flow Simulations 2D “shallow water” equations Equations from Iverson and Denlinger, Journal of Geophysical Research, Vol. 106, No. B1, pp. 537-552, Jan. 10, 2001.

An Overview of the Simulation Code Name: Titan2D Hyperbolic, vector PDE Frame invariant Numerically simulated using a Godunov solver (first and second order) Runs in parallel using MPI Currently works on crosby.ccr and the Linux boxes in the trailer Plan to make it work on nash.ccr and joplin.ccr

Simulation Outputs Tecplot (2 different types) tecplotter() tecplotxxxx.plt (xxxx is time step number) meshplotter() mshplotxxxx.plt (xxxx is time step number) Version for Pady’s Visualization viz_output() viz_filename.out, viz_outputxxx.out (xxx is the processor number) HDF (not fully implemented yet) hdf_output()

Getting the Code Code is stored on fire.ccr.buffalo.edu using ‘cvs’ for storage Getting the code for running simulations cvs export -D yyyy-mm-dd 2D_FD_SIMULATION where yyyy-mm-dd is the date (suggest setting the date to the next day’s date for most recent version, e.g. 2003-01-15 on Jan. 14, 2003) Instructions for code developers on using cvs www.cvshome.org

Code/Directory Structure 2D_FD_SIMULATION directory is created where the cvs export command was done. WARNING the cvs export command may wipe out information in an already existing 2D_FD_SIMULATION sub-directory of the current working directory.

Running the Simulation Read the README file first Command is python runit.py Must be executed from the bin directory On crosby use /usr/local/python2.1/bin/python instead of python Currently runs on crosby.ccr and the Linux boxes in the trailer Will run on nash.ccr and joplin.ccr soon

The Python Script For detailed information for entering information, see the README file

Pile Height Specification Allows multiple piles Pile information window pops up after the user hits the Run button in the main window Individual piles have the shape of a paraboloid After entering the proper information, first hit the Done button and then hit the Quit button

Figuring Out the Total Volume The Calculate Volume button gives the volume for only individual piles Sum of the individual pile volumes will not be equal to the total volume for overlapping piles The pile height in a region of overlapping piles will be the maximum height of the individual piles at that point

Improper Pile Extents The user may get 0 pile volumes if the grid spacing is too large for the desired pile extents Increase the value of the number of computational mesh points in the y-direction in the python script. Want the pile to cover atleast 4 cells in each direction.