we are going to implement a custom drag model which is modified for the base case of the Ishii Zuber drag model
For this follow the following steps,
step 1) download the 'IshiiZuberModv' folder and paste it into the run directory in OpenFOAM
step 2) using cd command go into the folder in the terminal.
step 3) type "wclean" command in your terminal; this cleans the existing mapped code
step 4) type "wmake" command in your terminal; this compiles the custom code that is used.
step 5) To use this you need to add the following command in your controlDict file "libs ("libIshiiZuberModvModel.so"); // In this case it is already added 

To run the case files follow the steps mentioned below,
step 1) Download the case_files folder and paste it in  your run directory
step 2) Using cd command go into the folder in the terminal and type the command bash ./Allrun to execute the sequence of commands to be executed.
step 3) the results can be viewed using the paraview software using paraFOAM command.
