A numerical scheme is developed in order to calculate the heat transfer and pressure drop coefficients in heat exchangers made of flexible tubes. The vibrating tubes are modeled in a quasistatic way by taking the first tube of the row to be in 15 asymmetric (with finite eccentricity) positions with respect to the rest of the tubes and averaging in time the steady-state solutions corresponding to each one of these geometries.The results show that the eccentricity of the first tube affects the velocity and temperature profiles significantly.The time-averaged heat transfer and pressure drop coefficients are higher than those for the case of rigid, symmetrically placed, tube bundles.Comparison of the present results shows very good agreement with experimental data from flexible tube heat exchangers.