README.md

# MFIX_TIM_squeeze_package
MFIX code for DEM simulation of TIM squeezing with associated user-defined functions

Please download MFIX v18.1.5 source code from https://mfix.netl.doe.gov/mfix/ (registration required)

This repository contains MFIX input file and user-defined functions (UDFs) for simulating squeezing of TIMs.In addition, compile instructions are provided below 

### Main inputs
Main input file -- mfix.dat
<br/> The main input file contains DEM simulation parameters

### Additional inputs
Additional inputs -- particle_input.dat and part_diameter.txt
<br/> These input files store the particle locations (first three columns of particle_input.dat) and particle diameters (part_diameter.txt). In addition, the second, third, and fourth-sixth columns of particle_input.dat file represent particle radius, density and their initial velocity. The radius value in this file must be constant and is just a placeholder for the squeeze simulations. For instance, in the attached file, the radius is 50 micron. 

### Other files needed
UDFs and job submission file (job_submit.sh) to schedule the simulation job on a compute cluster. The job submission file is provided as a template. In line 3 of that file, queue name must be provided.


### Compile instructions
First make a folder with a suitable name and copy these files: (a) mfix.dat, (b) particle_input.dat, (c) part_diameter.txt, (d) job_submit.sub
Then, make a folder with name "des" and copy the two UDFs there. Then, compile and submit the simulation job

1. Load relevant modules
   <br/> *Command*: source ~/loadmodules.sh

2. After loading modules, run the "cmake" and "make" commands
  <br/> \<path to mfix v18.1.5> is the path to MFIX source code 18.1.5 on your machine
  <br/> Note the "&&" in the following line, it will run "cmake" and "make" in succession. Otherwise, you can type it independently
  <br/> *Command*: cmake \<path to mfix v18.1.5> -DCMAKE_Fortran_COMPILER=gfortran -DCMAKE_Fortran_FLAGS="-g -O2" -DENABLE_OpenMP=0 -DENABLE_MPI=0 && make -j 2 

3. Submit job file on the compute cluster
   <br/> If your compute cluster uses the SLURM scheduler, "sbatch" is the command for submitting the job file. Otherwise, discuss with IT personnel
   <br/> *Command*: sbatch job_submit.sh

4. Run simulation without submitting job file
   <br/> In step 3 above, the job submission file requests resources on a SLRUM workload manager instead of executing the simulation immediately. However, if you wish to run the simulation on a dedicated computer, then the simulation can be executed using the command "./mfixsolver &> output_mfix".
   <br/> Here, "./mfixsolver" runs the executable "mfixsolver", which will appear after successfully compiling (step 2)
   <br/> "&> output_mfix" will show the simulation output in the file *output_mfix*. If you do not specify this, then the outputs are printed on the display


### Verification simulation
To verify a smooth execution of the TIM squeeze simulation, please follow the above instructions and execute a simulation *without* modifying anything in the input files