Propulsive characteristic of helical screw based on flagellum of swimming bacteria


 

Propulsive force generated by helical screw propellers based on bacterium flagellum was measured. We made a model of a helical screw and calculated the propulsive force produced by the helical screw. This model was made by separating the drift force into the vertical and horizontal direction because in low Reynolds number flow drift force is dominant. We used fifteen helical screws of different diameter and length. We measured the propulsive force of these helical screws by rotating them in glycerin. We also observed the surrounding water in order to measure the relative speed of the water. The difference between measured propulsive force and calculated propulsive force remained within 30% by taking the relative speed in count.