I think the prefix ‘foru-’ فرو , implies a downward type of movement. Is that right?

Yes, that’s correct. Foru- فرو (variant of forud فرود ) means ‘down; downward; low’. For example: foru-rixtan فروریختن ‘to collapse’, foru-maaye فرومایه ‘abject, ignoble’ [formal].