# Copyright (c) 2017 Nikhil Admal/Jaime Marian

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# Author: Nikhil Admal

This file describes the COMSOL implementation of a three-dimensional diffuse-interface 
polycyrstal plasticity developed in the paper:

    Nikhil Chandra Admal, Giacomo Po, Jaime Marian. 
    “Diffuse-interface polycrystal plasticity: Expressing grain boundaries 
    as geometrically necessary dislocations.” Materials Theory, 1(1):6, 2017

The boundary-value-problem simulated is for a three-dimensional polycrystal. 
See the above reference for additional details regarding the model.

This directory consists of the files

    README
    polycrystal.m
        cdf.m
        logcdf.m
    expressions.m
        levCiv.m
    poly_cp.mph

Following are steps to be followed to run the poly_cp.mph:

1) An initial polycrystal with a log-normal distribution of grain sizes is generated using 
   the 'polycrystal.m' (depends on 'cdf.m' and 'logcdf.m') matlab file. The polycrystal is 
   outputted as three .txt files: 'orientation1.txt', 'orietation2.txt' and 'orientation3.txt'. These
   files are subsequently read into COMSOL when executing poly_cp.mph.

2) Run the 'expressions.m' (depends on 'levCiv.m') matlab file which is used to generate two .txt files:
   a) 'variables.txt' and b) 'pde.txt', which are used as input for variable definitions and weak
   form pdes in COMSOL v5.2 file 'poly_cp.mph'. 

3) Open the 'poly_cp.mph' COMSOL file. The 'poly_cp.mph' file, in its current form, has the variables 
   and the pdes already inputted. So, step 2 above may be skipped. Instead, if you intend to make any 
   changes to the model by altering the expressions.m file, then the new variables.txt and the pde.txt 
   files are to be included as follows:

   The files variables.txt are uploaded in the tabs (of COMSOL v5.2)

        Component 1 -> Definition -> variables.

   The weak-form pdes in the file 'pde.txt' are pasted into the
   PHYSICS tab:

        Force Balance       -> Weak Form PDE1


   Finally, the files orientation*.txt generated in step 1 are read in the tabs

        Global Definitions -> interpolation 1/2/3

4) Run the poly_cp.mph file.