How to plot streamlines and isotherms?
 

Hello everyone, I am learning to write a code for natural convection in square cavity using stream vorticity formulation in fortran and want to plot streamlines and isotherms but I don't know how to do that. Could you please suggest me some source where I could learn this.
Also the output file I am getting using write(1,*) x(i),y(j),psi(i,j) is not in column format, so how can I write data in different columns in Fortran?

Usually, the graphics is done in a post-processing phase using other softwares.... you can use Tecplot, Matlab, Gnuplot, ecc. and I suggest to see the documentation for the correct output file to be written.