A Guide to DoubleDip

DoubleDip is part of the Fondue Family.

There is an associated program called Fondue that produces the input files for DoubleDip.

DoubleDip is free and can be re-distributed under the terms of GNU General Public License. This is an implementation of the Copyleft concept provided by the Free Software Foundation.

Overview

DoubleDip is the first of a series of intermediate-processing programs. DoubleDip is designed to assist the Fondue user in remapping a fine meshed problem onto a coarser meshed problem. This is a rather specialized operation, but it may be of use to some users. This remeshing can be useful if the user wants to examine the growth of some spot from a very small size to a very large size. If one mesh were used throughout, the number of mesh points might be prohibitively large. (Fondue doesn't have variable mesh spacing.)

The premise for DoubleDip is that for many simulations, the small scale behavior is only needed for the beginning of the simulation. Once the small mesh is not needed, the old problem can be mapped onto a new problem with the mesh spacing twice as large, i.e. dr -> 2*dr. Two mesh elements in the old problem get mapped onto one element in the new problem. The mapping of 2 onto 1 requires an averaging of the two elements and in the case of the radial mapping, this is a weighted average (by surface area).

DoubleDip will take a binary save_disk file produced by Fondue and produce a new save_disk file that has the mesh spacing doubled. DoubleDip requires not only this save_disk file but also the summary file produced by Fondue. This summary file tells DoubleDip the format for the save_disk file. DoubleDip will produce a new set of files (save_disk and summary) that contain the results of the mapping operation. It is up to the user to modify the input file for Fondue to take advantage of the remeshed problem. For instance, the user should modify the description of any of the heat sources to be consistent with the new mesh.

DoubleDip is invoked from the command line by

   =doubledip [options] old_filename_stem [new_filename_stem]=

The options can appear in any position on the command line. If new_filename_stem is not present, the set of files specified by old_filename_stem will be overwritten.

Command Line Options

--radius

This specifies that the model will be remapped in the radial direction only. The Z direction will be unaffected.

--depth

This specifies that the model will be remapped in the depth direction only. The R direction will be unaffected.

--both

This specifies that the both directions of the model will be remapped. This is the default mode.

--help

A help message will be printed to stdout. This will be done instead of performing any operations. The brief "usage" statement will be printed along with a one-line description of the command line arguments.

--version

A message stating the version will be printed to stdout. This will be done instead of performing any computation.

--copying

A message stating the GNU Copying info will be printed to stdout . This will be done instead of performing any operations.

--warranty

A message stating the GNU No Warranty info will be printed to stdout . This will be done instead of performing any operations.

Examples

A few examples might be useful. Assume that I have run Fondue and created the files myrun.sum and myrun.sav . The model has Rpoints = 100 and Zpoints = 10. Radius = 5E-2 and Depth = 5E-3. I might try the following:

   doubledip myrun mynewrun

will remap the data saved in myrun.sav and myrun.sum onto a problem with the same number of meshpoints in each direction but with

Radius = 1E-1 and Depth = 1E-2.

   doubledip --radius myrun mynewrun

will map only the radial values and result in Radius=1E-1 and Depth=5E-3.

   doubledip --depth myrun mynewrun

will map only the radial values and result in Radius=5E-2< and Depth=1E-2.