A pumping mechanism is described that includes a peristaltic pumping mechanismhaving an inlet and an outlet. The pumping mechanism configured to receive afluid throughthe inlet and provide an output flow of the fluid through the outlet at a ratethat variesperiodically over time about a nominal flow rate. The pumping mechanism alsoincludes avariable volume having an inlet fluidically coupled to the outlet of thepumping mechanismand an outlet. The variable volume is configured to vary synchronously with aperiodicvariation of the output flow.
