Hydraulic jump is one of the most important phenomena in a  rapidly varying flow. This phenomenon occurs in free surface flow and transforms the flow from supercritical into subcritical. The transformation causes the depth to increase within a short distance. In the present study, characteristics of a hydraulic jump in contractions and expansions with straight and curved walls were investigated for five Froude numbers in the range of 5.8-9.1. The values of depth and velocity were measured in different sections of the hydraulic jump  that occurred in the transitions. The values of energy dissipation in the expansions with straight and curved walls averaged 24.95% and 21.23%, relatively. In the contractions, the energy dissipation averaged 15.93% and 12.49%. Also, the results showed that the Reynolds stresses in the contraction and the expansion increased and decreased relatively by increasing the longitude distance from the beginning of the jump.

contraction, dissipation energy, expansion, hydraulic jump, Reynolds stresses.