The determination of ‘added mass’ of swimmers as a part of studies of unsteady flow

Biography

Dr Bodo E Ungerechts is member of the ‘Steering Group of the Conference Series -Biomechanics and Medicine in Swimming. He studied biology, sport science and mathematics. During the period he was completing his PhD Bodo was still an active swimmer and became a consultant of coaches to discuss aspects of propulsion in sport swimming, e.g. one of the swimmer he worked with established world record on 100 m breaststroke in 1977. Later he organised the education of top coaches for the German Swimming Federation and he is still acting as a lecturer. He conducted the first experimental tests for enterprises studying the influence of fabrics and swim wear on the swimmers’ speed. Presently Bodo working as Affiliated Professor at Bielefeld University/Germany, Dept. Neurocognition and Action Biomechanics.

Synopsis

Swimming is a combination of buoyancy and self-induced propulsion under the conditions of cognitive control and limited energy reserves. While the buoyancy acts permanently, self-induced propulsion fluctuates due to the cyclic interaction of the body and water masses, resulting in unsteady flow conditions. There are consequences not only for the calculation of the braking forces. Commonly the braking effect due to flow (D) is determined by towing tests. Here the constant speed (u) is stepwise increased and the result (FW/u) is represented as a curve. The effect that occurs with the change of speed (a), e.g. from start to constant speed, is not recognised. The change (a) is coupled with unsteady flow phenomena. Now the functional relationships between effects to speed and acceleration, respectively are governing braking effects. These functional relationships are detectable by a mathematical model, with an acceleration-related proportionality factor from the experimental linear relationship between drag and speed, which has the unit of mass, as additive mass (called ‘added mass’), respectively. The aim of this paper is the individual determination of the ‘added mass’ of swimmers.