For laminar flow the friction factor varies linearly with 1Re so the head loss or pressure drop varies linearly with velocity just as the OP surmised. I believe whether or not its turbulent or laminar or mixed is based on the Reynolds number. Reynolds Number Laminar And Turbulent Flow Science Project Education Com Reynolds Number Flow Education Com Viscous force is more prominent due to the slower flow rate. . A flow is considered turbulent if the Reynolds number is greater than 3500. 131 1173 Dissipation term εij. The critical Reynolds number is associated with the laminar-turbulent transition in which a laminar flow becomes turbulent. Between these two values is critical zone where the flow can be laminar or turbulent or in the process of change and is mainly unpredictable. Laminar flow is the type of flow in which the fluid travels smoothly in regular paths. It also depends on the diameter of the outlet so that the larg...