TRANSPORT IN BRANCHED SYSTEMS .2. TRANSIENT-RESPONSE

Branched or fractal-like extended surfaces are commonly found in natural systems and are incorporated in engineered systems to enhance the rate of heat or mass transfer, or to enhance the rate of chemical reaction. Many of these systems are required to respond to periodic inputs or to produce periodic outputs. Simple models can be derived to simulate the transport effectiveness and efficiency of these engineered structures and thereby provide some speculation concerning the evolutionary design and environmental control of natural branching systems. The branched structures respond like classic, multi-pole, R-C low-pass filters whose cutoff frequencies and attenuations depend upon the extent of branching and the physical properties of the system. The low-pass filter response is advantageous because normal disturbances either in the external or internal environment are damped out before they are propagated and processed by the transmitter or the receiver. This is especially important in neural networks controlling heartbeat or the processing of information in the brain.