The Case 3 tests were similar to Case 1 with the main difference being the

angle of the flow separation surface at the gap (see Figure 18(c)). Case 1 used

vertical edges as gap boundaries, whereas the Case 3 tests used sloping edges as

boundaries. Turbulence generated at sloping boundaries was expected to have

significant vertical components; and hence, a turbulent scale effect was expected

to occur.

The prototype for Case 3 had edge slopes of 1:1, or 45 deg. However,

different horizontal and vertical length scales resulted in steeper edge slope

angles as distortion increased. For model distortions of Ω = 2, 4, and 6, the

corresponding edge slopes were 63 deg (2:1), 75 deg (4:1), and 80 deg (6:1),

respectively. Figure 33 illustrates the relative distortion of the Case 3 tests and

defines the length parameters *X*p, *X*m, *Z*p, and *Z*m. The horizontal dimensions

across the gap are taken at middepth.

The prototype case, and scaled models of the prototype having distortions

ratios (*N*X/*N*Z) equal to 2, 4, and 6, were tested for two flow rates (*Q *= 1.5 L/sec

and 1.0 L/sec). This gave a total of eight experiments. Scaling factors for each

test in the series along with relevant values for discharge and key horizontal

(*X*p, *X*m) and vertical (*Z*p, *Z*m) dimensions were the same as the first eight tests of

Case 1 as listed in Table 5. The horizontal measurement grid was the same as

Case 1, and the grid spacing (∆x, ∆y) for each experiment was the same as listed

in the first eight rows of Table 6. Preliminary dye injection into the flow

indicated significant vertical structure to the turbulent flow. Consequently, the

flow velocity vector field was measured at two depths (one-third and two-thirds

of the water depth (*d*) above the bottom) for each experiment.

Partial graphical results obtained from the four tests conducted with a

discharge scale of *N*Q=1*.*0 (*Q *= 1.5 L/sec) are presented here as representative of

this test configuration. Complete graphical results for all eight Case 3 tests are

included in Appendix C.

Measured velocity vectors for the prototype case at an elevation 2/3 *d *above

the bottom are shown in Figure 34, and the corresponding results from models

with distortion 2, 4, and 6 are shown scaled up to prototype in Figures 35, 36,

and 37, respectively. Scaling was performed using the scale factors listed in

Table 5. A similar distinct jet flow with minimal lateral spreading is seen in all

the velocity vector plots recorded at an elevation of 2/3 *d *above the bottom.

Corresponding vector plots recorded at a water depth 1/3 *d *above the bottom

are presented in Figures 38-41. In the prototype test at the lower water depth

there is noticeable spreading of the jet as evidenced in Figure 38. Jet spreading

decreased as distortion increased and the sloping edge became more vertical as

seen in Figures 39-41.

53

Chapter 5 Turbulence Scale Effects Experiments

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