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Taylor dispersion in equilibrium gradient focusing at steady state
- Ivory, Cornelius F.
- Electrophoresis 2015 v.36 no.5 pp. 662-667
- dispersions, electrophoresis, equations, flow, solutes
- An analytic expression is presented for the effective dispersion coefficient in the case where a solute is focused in a parabolic flow against a linear gradient in a restoring force. This expression was derived by employing a minor variation on the method of moments used by Aris in his development of the dispersion coefficients for a time‐dependent, isocratic system. In the present case, dispersion is controlled by two dimensionless groups, a Peclet number which is proportional to the parabolic component of the flow, and a gradient number which is proportional to the slope of the restoring force. These results confirm that the Aris–Taylor expression for the dispersion coefficient should not be applied in cases where a solute is focused to a stationary steady state.