In this book, the authors address present-day methodology to explore natural phenomena. Highly advanced computational fluid mechanics contributes to the rationalization of experimental work. By taking sandy beach and tidal flat eco­ systems as an example, results from interdisciplinary collaboration between envi­ ronmental experimentalists and applied mathematicians are presented in an inte­ ractive manner. In 1994, an environmental study group from Hiroshima University started a study on tidal flats. Based on fieldwork, they discovered the importance of fluid flow in understanding the biological activities of tidal flats and sandy beaches. ofbacteria on the seabed strongly correlates with the They found that the number amount ofsilt (fine sand