Here we disclose a Boycott Separator to separate, dilute/concentrate, or remove particles from flows. To perform particle separations, this new class of separators uses the Boycott effect, in which which settling particles interact with an angled surface to accelerate particle motion toward the bottom of the channel. Here the angled surface is oriented with at least partially with some orthogonality with respect to the flow. Fin arrangements of such surfaces are also disclosed. Numbering up of such surfaces or fins is also disclosed. We also disclose a shallow angle of entry to minimize the length of the device by eliminating recirculating entry zones. Please see subsequent sections for history, problem, relative advantages, etc.