Acceleration of swimming bacteria at ``zero" Reynolds number

Self-propelled objects can accelerate at ``zero'' Reynolds number Re. An incompressible fluid responds ``instantaneously'' and globally to the motion of bounding surfaces. When the propulsion mechanism of a bacterial body, a helical bundle of flagella, forms and rotates, the body accelerates according to $F = ma$, where $F$ is the sum of forces exerted on the body: drag plus the thrust of the flagella. The flagellar rotation instantly moves all the surrounding fluid, as does the body`s motion on, acting on its surround. The acceleration of bacteria stopped by a collision and beginning reverse swimming is important in the analysis of the jammed phase in the onset of Zooming BioNematic (ZBN). An instantaneous one step displacement has been used to analyze the flow surrounding swimming bacteria.