Coupled plate height equation

The plate height equation that incorporates the coupling theory introduced by Giddings [ref. 5] is expressed as... 

The last two equations are two forms of the coupling equation for mobile phase plate height [1]. Coupling refers to the way in which flow and diffusion act in concert to reduce step length and thus plate height. 

The coupling equations shown above are applicable to one kind of velocity bias, such as that between adjacent channels. However, the theory is more or less the same for the other kinds of velocity biases listed previously, but the constants (a>fi9 a>A, (oa) are different, yielding different a> and A in the foregoing coupling expressions. Each kind of velocity bias generates its own independent random walk, leading to an additive plate height term H,. The overall mobile phase term is therefore the sum... 

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