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

2. 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

3. 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()

4. 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 on Jan. 14, 2003)
Instructions for code developers on using cvs

5. 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.

6. 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

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

8. 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

9. 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

10. 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.