USA). His collaboration with McDonald may have been prompted by his eldest daughter, Barbara, who was studying medicine at St Bartholomew's. Whatever the reason, this move led to a new and highly productive period in his research, as he applied mathematical and computational techniques to the analysis of blood flow and hemodynamics. Most notably in 1955 he published an article which described a dimensionless parameter (α) which characterised the nature of unsteady flow; subsequently this has been called the Womersley number. In July 1955, as planned, he moved to WADC to take a post as acting chief of the Analysis Section, System Dynamics Branch Aeronautical Research Laboratory. In 1956, he was promoted to Supervisory Mathematician and then Supervisory Aeronautical Research Engineer (Flight Systems), although he continued to publish on mathematical aspects of blood flow until his early death in 1958. His 1957 monograph on 'An elastic tube theory of pulse transmission and oscillatory flow in mammalian arteries' is widely regarded as a major influence in the field. In 1957 he returned to Britain for treatment of cancer. He underwent a number of operations in London and returned to Ohio in 1957, but never fully recovered and died at Ohio State University Hospital, Columbus, on 7 March 1958. Personal life Womersley married Jean Isobel Jordan in Hammersmith, London in 1931. The couple had three daughters, Barbara, Ruth and Marion. Womersley's wife, Jean lived in Dayton until 1996, and as of 2014, they were survived by two daughters and six grandchildren living in the US and Canada. Selected publications Womersley, JR (1957). An Elastic Tube Theory of Pulse Transmission and Oscillatory Flow in Mammalian Arteries, Wright Air Development Center Technical Report 56-614, (sometimes referred to as WADC TR56-614 and sometimes cited as 1958) A complete bibliography was compiled by Brian E. Carpenter and Robert W. Doran References 1907 births 1958 deaths 20th-century British mathematicians Fluid dynamicists History of computing in the United Kingdom