Diffusion & Mixing Time Estimator
Calculate mixing time and assess diffusive mixing in microchannels
Input Parameters
D = 1.00e-9 m²/s
Results
Diffusion Time
5000.00 ms
Péclet Number (Pe)
0.100
Diffusion dominated (good mixing)
Required Mixing Length
0.01 mm
for full diffusive mixing
Residence Time
10000000.00 ms
✓ Mixing is COMPLETE
Residence time (10000000.00 ms) ≥ diffusion time (5000.00 ms)
About Microfluidic Mixing
Mixing in microfluidics depends on diffusion and advection. The Péclet number (Pe) quantifies their relative importance.
Diffusion Time: t_diff = w² / (2D) — time for a molecule to diffuse across the channel width by diffusion alone.
Péclet Number: Pe = Uw / D — ratio of advective to diffusive transport.
Mixing Length: L_mix = Pe × w — the minimum channel length needed for two streams to fully mix by diffusion.
Mixing Assessment:
- • Diffusion dominated (Pe < 1): Good passive mixing
- • Transitional (Pe 1-10): Moderate mixing, may need longer channels
- • Advection dominated (Pe > 10): Poor passive mixing, consider active mixing
Microfluidics enables excellent mixing compared to macroscale devices due to small channel dimensions, but high flow velocities can suppress it.