This question already has an answer here:
I'm in the Physics community. I've already published an article on a journal where I've described a solution scheme that serves to solve a certain problem. Now, I've discovered that the same approach can be used to solve a different model. Of course the model, the comments the results, the plots, etc are different, but the technique is the same. So, is it ok to copy the section of my previous article where I describe the solution technique and paste it into the new one? Notice that the old and the new article feature the same identical authors and that the previous article would be, of course, properly cited.