Reynolds number (Re)

The Reynolds number Re = ρvDₕ/μ is the ratio of inertial to viscous forces. Low Re means viscosity dominates and flow is laminar; high Re means inertia dominates and turbulence can appear.

Microchannels have small length scales and modest velocities, so Re is usually far below the ~2000 pipe-flow transition — a quick calculation confirms you are in the laminar regime.