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Dimensional analysis and scaling relevant to flow models of thrombus formation: communication from the SSC of the ISTH

Flow chambers are increasingly used to model thrombus formation in (patho)physiologically inspired geometries and conditions. The flexible design enabled by microfluidics and the variety of commercially available devices makes comparisons between flow chambers challenging [1]. There is also a need to make faithful comparisons between these in vitro models and animal models. Dimensional analysis and scaling provide a rigorous method for making these comparisons. Scaling is a mathematical tool used to simplify, characterize and design systems based on their dimensions and dynamics. Scaling arguments to describe biophysical mechanisms that regulate thrombus growth have recently appeared in hematology journals [2,3]. In practise, scaling involves selecting important dimensional and dynamic parameters and forming dimensionless groups that characterize a system [4]. These dimensionless groups determine the relative importance of geometric features, forces and rates. The purpose of this Communication is to provide a primer on scaling and provide recommendations for reporting and calculating relevant dimensionless groups in flow models of thrombus formation.