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<br /> <br />DRAFT <br /> <br />Velocity measurements were taken using Marsh McBimey electromagnetic flowmeters and 011 <br />current meters. Surface velocities and directions were obtained by taking time lapse pictures of <br />model boats traversing the area. <br /> <br />Hydraulic Similitude <br /> <br />Hydraulic similitude must exist between model and prototype to obtain accurate flow measurements <br />in the model. The inertial force is the vector sum of all forces. When gravitational forces <br />predominate, which is the case with most open channel hydraulic structures, a basis for similitude <br />can be established by equating the ratio of gravitational forces to inertial forces and neglecting the <br />other forces. Flow in the model was simulated by using the dimensionless Froude number which <br />relates inertial force to gravity force. <br /> <br />V <br /> <br />(1) <br /> <br />Lg <br /> <br />Using the Froude number, model and prototype parameters can be determined from the <br />following similitude equations: <br /> <br />F = <br />, <br /> <br />L, L" 18 <br />= = <br /> L", <br /> 2 <br />A = L, = 324 <br /> <br />(2) <br /> <br />(3) <br /> <br />V. <br /> <br />, <br />= L r <br /> <br />= 5,832 <br /> <br />(3) <br /> <br />T, <br /> <br />1/2 <br />:: Lr <br /> <br />:: 4.24 <br /> <br />(5) <br /> <br /> 1/2 <br />V, = L, = 4.24 <br /> '"' <br />Q, = (L,) = 1,375 <br />Where: <br /> <br />(5) <br /> <br />(7) <br /> <br />L, = length ratio <br />A, = area ratio <br />V. = volume ratio <br />T, = time ratio <br />V, = velocity ratio <br />Q, = discharge ratio <br />Subscripts m and p refer to the model and prototype, <br />and r is the ratio between model and prototype. <br /> <br />3 <br />