I am trying to do different simualtions in openfoam, but i always have problem while specifying internla field option
i mean i've tried to simulate steady , as well as transient , but every problem that i simulated has BCs with it, and none of the problem has internal field specified with it
The internalField in OpenFOAM initialises the domain with values of all the fields at t=0 (or any other startTime). This is absolutely necessary in any numercial method to solve a time-dependent PDE, not just in OpenFOAM. If you clearly see the problems that you migh've solved already, which you feel didn't have the internalField, you will see that in all the files in the 0 folder, just before the boundary conditions are specified, the internalField is also specified. In most cases, this internalField is uniform, but OpenFOAM does allow non-uniform initialisations too, through the setFields utility. I hope this helps.
@-geometry dash: please do a sudo apt-get update on your system before running the installation script else, you could use a virtualBox for running Ubuntu 16.04