1. Looking at the microworld with the naked eye Can the slow motion of something very tiny be similar to a quicker motion of something considerably larger? Maciej Lisicki Maria Ekiel - Jeżewska

2. What does it mean 'similar'? Identical shape is not enough... http://www.tukan-webdesign.de/krusenstern2/Krusens%20neu%20als%20Taste%20m.Schatt400x383.jpg http://www.mmszczecin.pl/8307/2007/9/20/klub-czytelnika-zaprasza?category=interwencje

3. L ρ, μ U Reynolds number Density and viscosity of the liquid Flow velocity Characteristic size

4. Flow similarity principle Two flows having the same Reynolds numbers have the same character. Low viscosity, little size, low velocities = High viscosity, big size, high velocity

5. Low viscosity + little objects Welcome to the microworld! Rhodobacter E. coli Howard Berg’s Laboratory BACTERIA IN WATER

6. High viscosity + large objects MACROWORLD MICROWORLD Re

7. Flows with similar Reynolds numbers are similar! Instead of looking at swimming microobjects, we can observe large bodies but in a Very Viscous Liquid!