Electrochemistry MAE- 212. Dr. Marc Madou , UCI, Winter 2014 Class V Transport in Electrochemistry (II) . Table of Content. Reynolds Numbers Low Reynolds Numbers OHP, Diffusion Layer Thickness, Hydrodynamic Boundary Layer Thickness
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Dr. Marc Madou, UCI, Winter 2014
Class V Transport in Electrochemistry (II)
where v is the mean velocity of an object relative to the fluid (SI units: m/s), L is a characteristic linear dimension (SI: m),μ is the dynamic viscosity of the fluid [SI: Pa·s or N·s/m² or kg/(m·s)] and ν is the kinematic viscosity (ν: μ / ρ) (m²/s) and r is the density of the fluid (SI: kg/m³)
which is the ratio of:
Typical size of a chip
Micro and nano technology enabled
Extended lenght of DNA
Microstructure and micro-drops
Radius of Gyration of DNA
Colloid and polymer molecular size
Nano-tubes (some of the smallest channels).
where δ is defined as the boundary layer thickness in which the velocity is 99% of the free stream velocity (i.e., y = δ, u = 0.99U).
with U, fluid velocity; ν, kinematic viscosity; and D, diffusion constant.
with kinematic viscosity,n, and mass diffusivity Dc.
the Prandtl layer is 10 to 30 times thicker than the Nernst layer.
where B and a are constants for a given system. As a result, the concentration gradient becomes steeper, thereby increasing the limiting current. Similar considerations apply to other forced convection systems, e.g., those relying on solution flow or electrode rotation. For all of these hydrodynamic systems, the sensitivity of the measurement can be enhanced by increasing the convection rate.