Co-Current flow is like counter-current flow, but there is some difference in flow regimes. In Co-Current flow feed and permeate flow in a same direction.
In Co-Current flow like counter-current flow, the feed flows on the shell-side. The feed thus contacts the outside of the fibers or flat membrane, and part of the solute permeates to the bores of the fibers or flat membrane. The fibers are closed at one end, so permeate is discharged from one end only. Good distribution of flow on the shell-side is a design problem for large diameter units.

Recently studies in a stratified counter-current flow has been studied experimentally and it has been shown to be more efficient than co-current flow. It is shown that the counter-current process is superior to the co-current process for the same set of parameters and operating conditions.