Steps to run the case :- 

1) Open the run directory as per your console using the command: cd $FOAM_RUN.

2) Then direct to the case file using the command: cd <casefilename>.

3) run command : "blockMesh" //to create and mesh the geometry from the blockMeshDict,

After successfully running the blockMesh command enter the next command.

4) run command : "buoyantSimpleFoam" for case of reynolds number 20 and 100, "buoyantPimpleFoam" for the case of reynolds number 200 //to solve as per the boundry conditions and the initial values provided in their respective case files.

After running the above command the simulation will start to run, after completion of simulation type. 

5) run command : "paraFoam" or // to open paraFoam for viewing/post-processing the results,
 
Next run the parafoam and see the contours and other results. 

Note:Allrun file provided may not work on every OpenFOAM version. If you encounter issues, delete those folders and follow the commands mentioned above.

ELSE

1) run command: ./Allrun //to run all the commands automatically through a script,

After running the above command the simulation will start to run, after simulation completes, type 

2) run command : "paraFoam" or // to open paraFoam for viewing the results,
 
Next run the parafoam and see the contours and other results as necessary.





.... Common Errors ......

If you experience errors, check the version of OpenFOAM you're using, as it may differ from the version the case was originally set up for. 

Solutions to other common errors can be obtained in CFD groups/blog posts etc. Documentation on openfoam solvers and boundary conditions can help explain a lot.
