The effect of source Reynolds number on the rise height of a fountain

The focus of this paper is to establish the effect of source Reynolds number, Re-0, on the mean rise heights of Boussinesq miscible fountains and thereby the range of Re-0 for which rise heights are independent of Re-0. We present results from experiments on aqueous-saline fountains spanning source Reynolds numbers of 15 <= Re-0 <= 4000 and source Froude numbers of 0.3 <= Fr-0 <= 40. We provide threshold values for the source Reynolds number, i.e., values above which fountain rise height may be regarded as independent of Re-0. For Reynolds numbers immediately beneath these threshold values, the fountain rise height increases as Re-0 decreases-in agreement with Lin and Armfield ["The Reynolds and Prandtl number dependence of weak fountains," Comput. Mech. 31, 379-389 (2003)]. At even lower Re-0, we show that the rise heights reach a maximum and that further decreases in Re-0 decrease the rise height attained-in agreement with Phillipe et al., ["Penetration of a negatively buoyant jet in a miscible liquid," Phys. Fluids 17, 053601 (2005)]. As such, we resolve an apparent inconsistency within the existing fountain literature. (C) 2015 AIP Publishing LLC.