TY - JOUR
TI - Flow structure from a horizontal cylinder coincident with a free surface in shallow water flow
AU - Kahraman Ali
AU - Özgören Muammer
AU - Şahin Beşir
JN - Thermal Science
PY - 2012
VL - 16
IS - 1
SP - 93
EP - 107
PT - Article
AB - Vortex formation from a horizontal cylinder coincident with a free surface of  a shallow water flow having a depth of 25.4 [mm] was experimentally  investigated using the PIV technique. Instantaneous and time-averaged flow  patterns in the wake region of the cylinder were examined for three different  cylinder diameter values under the fully developed turbulent boundary layer  condition. Reynolds numbers were in the range of 1124£ Re£ 3374 and Froude  numbers were in the range of 0.41 £ Fr £ 0.71 based on the cylinder diameter.  It was found that a jet-like flow giving rise to increasing the flow  entrainment between the core and wake regions depending on the cylinder  diameter was formed between the lower surface of the cylinder and bottom  surface of the channel. Vorticity intensity, Reynolds stress correlations and  the primary recirculating bubble lengths were grown to higher values with  increasing the cylinder diameter. On the other hand, in the case of the  lowest level of the jet-like flow emanating from the beneath of the smallest  cylinder, the variation of flow characteristics were attenuated significantly  in a shorter distance. The variation of the reattachment location of the  separated flow to the free-surface is a strong function of the cylinder  diameter and the Froude number.