Brush seal is a novel contact seal in turbomachinery. Although this new type of seal has been adopted for many years, there are still some problems which should be investigated. One of the main problems is the determined pressure differential across a brush seal. Aerodynamic resistance, characterized by Euler number (Eu), is used to determine pressure differential of brush seals. Eu is a dimensionless quantity including a velocity term. Tube banks model is widely used in numerical simulation of brush seals. Various velocity values can be chosen by calculating Eu in a tube banks model. The present research analyzed the effect of different velocity values on Eu. Velocity choice in a tube banks model was preliminarily analyzed. Three different methods (Eu1, Eu2 and Eu3) for calculating Eu were presented. The results revealed that Eu1 decreases as the pressure differential increasing. Eu2 keeps almost unchanged or increase slightly with the growing of pressure differential, as well as Eu3. By comparing Eu1, Eu2 and Eu3 and considering practical application, Eu1 is qualified for measuring the aerodynamic resistance. © Springer Nature Singapore Pte Ltd 2019.