The flow rate of blood in an environment of weightlessness

Abstract

To discuss the decrease in the flow rate of blood experienced by astronauts, a theory of blood flow is presented taking account of the effect of gravity. The theory of two-dimensional Poiseuille flow is adopted. It is assumed that the flow is horizontal and that the width of the upper marginal layer filled with plasma thickens as gravity increases. The parameter ξ which mainly indicates the effect of thickening of the upper marginal layer is introduced. The extent of decrease in the flow rate of blood in the environment of weightlessness compared to that in the gravitational field is calculated for various values of ξ. The decrease is more remarkable in the flow rate of the cell fraction than that of whole blood for the same value of ξ.