Essentially smooth flow of a fluid or gas which can be modeled as the substance flowing in parallel layers. In a pipe the situation can be described by Poiseuille's law. Laminar flow has:
- High momentum diffusion
- Low momentum convection
- Pressure independent of time
- Velocity independent of time
Flows where inertial effects are small tend to be laminar and are associated with low Reynolds numbers. The alternative is turbulent flow which has much more of chaos theory about it with pressure and velocity of the substance varying with time.