2908 Thermoregulatory Analogies Between Plants, Skin, and Earthen Construction Materials

Saturday, February 19, 2011: 2:00 PM
145A (Washington Convention Center )
Lakshmi N. Reddi , University of Central Florida, Orlando, FL
Sustainable engineering practices and energy conservation of built environments are key issues of modern times, which caught research communities unprepared and overwhelmed.  Construction using stabilized earth constitutes one of the most sustainable engineering practices for human-built environments. However, stabilized earth construction is yet to catch up with the energy-efficiency in the naturally-evolved biological systems.  The purpose of this paper is to expose the thermoregulatory concepts in biological systems to show that biological systems offer both inspiration and  evolutionary knowledge to facilitate thermal regulation for stabilized earth dwellings similar to what a skin does to regulate the body temperatures in humans and animals.

The presentation first summarizes elements of heat transfer through stabilized earth elements.  The need to transform the passive heat transfer in these elements to an active process, activated by appropriate thermoregulatory effectors, is highlighted.  To address this need, attention is then focused on plant leaves and microcirculation in skin.  The engineering mechanisms operating through opening and closing of the stomata (minute pores in the epidermis of the leaf or the stem of the plant) to cool the leaf systems, are well understood.  The auto-thermoregulatory behavior exhibited by the skin vasculature is addressed in sufficient detail to draw out the analogies between the architectural systems of skin and soil pores, and the ranges of capillary and circulated flows of water in soils and blood in skin vasculature.  Heat exchanges due to secretion of sweat glands and blood circulation are conceptually and quantitatively compared with the heat exchanges occurring in soil systems.

The analogies drawn out are then used to identify the immense opportunities involved in biomimetics of civil infrastructure.  The ancient practice of building structures with stabilized earth embedded by plant leaves assumes new importance in light of these analogies.  The presentation will end after briefly addressing the following questions: i) to what extent could the eccrine sweat glands be imitated by soil capillaries? ii) could the clay minerals be so engineered to allow thermal shrinking and swelling, which could appropriately mimic the vasoconstriction/vascodilation of the arteriovenous anastomoses (AVAs) in skin (which in turn is analogous to stomata closing/opening in plant pores)?? and iii) is it feasible to represent the two plexuses (deep plexus and superficial plexus) in skin using strands of plant fibers?

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